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<!-- Dummy chapter -->
<chapter id='ref-variables-glos'>

<title>Variables Glossary</title>

<para>
    This chapter lists common variables used in the OpenEmbedded build system and gives an overview
    of their function and contents.
</para>

<glossary id='ref-variables-glossary'>


    <para>
       <link linkend='var-ABIEXTENSION'>A</link>
       <link linkend='var-B'>B</link>
       <link linkend='var-CFLAGS'>C</link>
       <link linkend='var-D'>D</link>
       <link linkend='var-EFI_PROVIDER'>E</link>
       <link linkend='var-FEATURE_PACKAGES'>F</link>
       <link linkend='var-GLIBC_GENERATE_LOCALES'>G</link>
       <link linkend='var-HOMEPAGE'>H</link>
       <link linkend='var-ICECC_DISABLED'>I</link>
<!--               <link linkend='var-glossary-j'>J</link> -->
       <link linkend='var-KARCH'>K</link>
       <link linkend='var-LABELS'>L</link>
       <link linkend='var-MACHINE'>M</link>
<!--               <link linkend='var-glossary-n'>N</link> -->
       <link linkend='var-OE_BINCONFIG_EXTRA_MANGLE'>O</link>
       <link linkend='var-P'>P</link>
       <link linkend='var-QMAKE_PROFILES'>Q</link>
       <link linkend='var-RCONFLICTS'>R</link>
       <link linkend='var-S'>S</link>
       <link linkend='var-T'>T</link>
       <link linkend='var-UBOOT_CONFIG'>U</link>
<!--               <link linkend='var-glossary-v'>V</link> -->
       <link linkend='var-WARN_QA'>W</link>
<!--               <link linkend='var-glossary-x'>X</link> -->
<!--               <link linkend='var-glossary-y'>Y</link> -->
<!--               <link linkend='var-glossary-z'>Z</link>-->
    </para>

    <glossdiv id='var-glossary-a'><title>A</title>

        <glossentry id='var-ABIEXTENSION'><glossterm>ABIEXTENSION</glossterm>
            <glossdef>
                <para>
                    Extension to the Application Binary Interface (ABI)
                    field of the GNU canonical architecture name
                    (e.g. "eabi").
                </para>

                <para>
                   ABI extensions are set in the machine include files.
                   For example, the
                   <filename>meta/conf/machine/include/arm/arch-arm.inc</filename>
                   file sets the following extension:
                   <literallayout class='monospaced'>
     ABIEXTENSION = "eabi"
                   </literallayout>
                </para>
            </glossdef>
        </glossentry>

         <glossentry id='var-ALLOW_EMPTY'><glossterm>ALLOW_EMPTY</glossterm>
            <glossdef>
                <para>
                   Specifies if an output package should still be produced if it is empty.
                   By default, BitBake does not produce empty packages.
                   This default behavior can cause issues when there is an
                   <link linkend='var-RDEPENDS'><filename>RDEPENDS</filename></link> or
                   some other hard runtime requirement on the existence of the package.
                </para>

                <para>
                   Like all package-controlling variables, you must always use them in
                   conjunction with a package name override, as in:
                   <literallayout class='monospaced'>
     ALLOW_EMPTY_${PN} = "1"
     ALLOW_EMPTY_${PN}-dev = "1"
     ALLOW_EMPTY_${PN}-staticdev = "1"
                   </literallayout>
                </para>
            </glossdef>
         </glossentry>

         <glossentry id='var-ALTERNATIVE'><glossterm>ALTERNATIVE</glossterm>
            <glossdef>
                <para>
                    Lists commands in a package that need an alternative
                    binary naming scheme.
                    Sometimes the same command is provided in multiple packages.
                    When this occurs, the OpenEmbedded build system needs to
                    use the alternatives system to create a different binary
                    naming scheme so the commands can co-exist.
                </para>

                <para>
                    To use the variable, list out the package's commands
                    that also exist as part of another package.
                    For example, if the <filename>busybox</filename> package
                    has four commands that also exist as part of another
                    package, you identify them as follows:
                    <literallayout class='monospaced'>
     ALTERNATIVE_busybox = "sh sed test bracket"
                    </literallayout>
                    For more information on the alternatives system, see the
                    "<link linkend='ref-classes-update-alternatives'><filename>update-alternatives.bbclass</filename></link>"
                    section.
                </para>
            </glossdef>
         </glossentry>

         <glossentry id='var-ALTERNATIVE_LINK_NAME'><glossterm>ALTERNATIVE_LINK_NAME</glossterm>
            <glossdef>
                <para>
                    Used by the alternatives system to map duplicated commands
                    to actual locations.
                    For example, if the <filename>bracket</filename> command
                    provided by the <filename>busybox</filename> package is
                    duplicated through another package, you must use the
                    <filename>ALTERNATIVE_LINK_NAME</filename> variable to
                    specify the actual location:
                    <literallayout class='monospaced'>
     ALTERNATIVE_LINK_NAME[bracket] = "/usr/bin/["
                    </literallayout>
                    In this example, the binary for the
                    <filename>bracket</filename> command (i.e.
                    <filename>[</filename>) from the
                    <filename>busybox</filename> package resides in
                    <filename>/usr/bin/</filename>.
                    <note>
                        If <filename>ALTERNATIVE_LINK_NAME</filename> is not
                        defined, it defaults to
                        <filename>${bindir}/<replaceable>name</replaceable></filename>.
                    </note>
                </para>

                <para>
                    For more information on the alternatives system, see the
                    "<link linkend='ref-classes-update-alternatives'><filename>update-alternatives.bbclass</filename></link>"
                    section.
                </para>
            </glossdef>
         </glossentry>

         <glossentry id='var-ALTERNATIVE_PRIORITY'><glossterm>ALTERNATIVE_PRIORITY</glossterm>
            <glossdef>
                <para>
                    Used by the alternatives system to create default
                    priorities for duplicated commands.
                    You can use the variable to create a single default
                    regardless of the command name or package, a default for
                    specific duplicated commands regardless of the package, or
                    a default for specific commands tied to particular packages.
                    Here are the available syntax forms:
                    <literallayout class='monospaced'>
     ALTERNATIVE_PRIORITY = "<replaceable>priority</replaceable>"
     ALTERNATIVE_PRIORITY[<replaceable>name</replaceable>] = "<replaceable>priority</replaceable>"
     ALTERNATIVE_PRIORITY_<replaceable>pkg</replaceable>[<replaceable>name</replaceable>] = "<replaceable>priority</replaceable>"
                    </literallayout>
                </para>

                <para>
                    For more information on the alternatives system, see the
                    "<link linkend='ref-classes-update-alternatives'><filename>update-alternatives.bbclass</filename></link>"
                    section.
                </para>
            </glossdef>
         </glossentry>

         <glossentry id='var-ALTERNATIVE_TARGET'><glossterm>ALTERNATIVE_TARGET</glossterm>
            <glossdef>
                <para>
                    Used by the alternatives system to create default link
                    locations for duplicated commands.
                    You can use the variable to create a single default
                    location for all duplicated commands regardless of the
                    command name or package, a default for
                    specific duplicated commands regardless of the package, or
                    a default for specific commands tied to particular packages.
                    Here are the available syntax forms:
                    <literallayout class='monospaced'>
     ALTERNATIVE_TARGET = "<replaceable>target</replaceable>"
     ALTERNATIVE_TARGET[<replaceable>name</replaceable>] = "<replaceable>target</replaceable>"
     ALTERNATIVE_TARGET_<replaceable>pkg</replaceable>[<replaceable>name</replaceable>] = "<replaceable>target</replaceable>"
                    </literallayout>
                    <note>
                        <para>
                            If <filename>ALTERNATIVE_TARGET</filename> is not
                            defined, it inherits the value from the
                            <link linkend='var-ALTERNATIVE_LINK_NAME'><filename>ALTERNATIVE_LINK_NAME</filename></link>
                            variable.
                        </para>

                        <para>
                            If <filename>ALTERNATIVE_LINK_NAME</filename> and
                            <filename>ALTERNATIVE_TARGET</filename> are the
                            same, the target for
                            <filename>ALTERNATIVE_TARGET</filename>
                            has "<filename>.{BPN}</filename>" appended to it.
                        </para>

                        <para>
                            Finally, if the file referenced has not been
                            renamed, the alternatives system will rename it to
                            avoid the need to rename alternative files in the
                            <link linkend='ref-tasks-install'><filename>do_install</filename></link>
                            task while
                            retaining support for the command if necessary.
                        </para>
                    </note>
                </para>

                <para>
                    For more information on the alternatives system, see the
                    "<link linkend='ref-classes-update-alternatives'><filename>update-alternatives.bbclass</filename></link>"
                    section.
                </para>
            </glossdef>
         </glossentry>

         <glossentry id='var-APPEND'><glossterm>APPEND</glossterm>
            <glossdef>
                <para>
                    An override list of append strings for each
                    <link linkend='var-LABELS'><filename>LABEL</filename></link>.
                </para>

                <para>
                    See the
                    <link linkend='ref-classes-grub-efi'><filename>grub-efi</filename></link>
                    class for more information on how this variable is used.
                </para>
            </glossdef>
         </glossentry>

         <glossentry id='var-ASSUME_PROVIDED'><glossterm>ASSUME_PROVIDED</glossterm>
            <glossdef>
                <para>
                    Lists recipe names
                    (<link linkend='var-PN'><filename>PN</filename></link>
                    values) BitBake does not attempt to build.
                    Instead, BitBake assumes these recipes have already been
                    built.
                </para>

                <para>
                    In OpenEmbedded Core, <filename>ASSUME_PROVIDED</filename>
                    mostly specifies native tools that should not be built.
                    An example is <filename>git-native</filename>, which when
                    specified, allows for the Git binary from the host to be
                    used rather than building <filename>git-native</filename>.
                </para>
            </glossdef>
         </glossentry>

         <glossentry id='var-AUTHOR'><glossterm>AUTHOR</glossterm>
            <glossdef>
                <para>The email address used to contact the original author
                    or authors in order to send patches and forward bugs.</para>
            </glossdef>
         </glossentry>

         <glossentry id='var-AUTO_SYSLINUXMENU'><glossterm>AUTO_SYSLINUXMENU</glossterm>
            <glossdef>
                <para>
                    Enables creating an automatic menu.
                    You must set this in your recipe.
                    The
                    <link linkend='ref-classes-syslinux'><filename>syslinux</filename></link>
                    class checks this variable.
                </para>
            </glossdef>
         </glossentry>

        <glossentry id='var-AUTOREV'><glossterm>AUTOREV</glossterm>
            <glossdef>
                <para>When <filename><link linkend='var-SRCREV'>SRCREV</link></filename>
                    is set to the value of this variable, it specifies to use the latest
                    source revision in the repository.
                    Here is an example:
                    <literallayout class='monospaced'>
     SRCREV = "${AUTOREV}"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-AVAILTUNES'><glossterm>AVAILTUNES</glossterm>
            <glossdef>
                <para>
                    The list of defined CPU and Application Binary Interface
                    (ABI) tunings (i.e.  "tunes") available for use by the
                    OpenEmbedded build system.
                </para>

                <para>
                    The list simply presents the tunes that are available.
                    Not all tunes may be compatible with a particular
                    machine configuration, or with each other in a
                    <ulink url='&YOCTO_DOCS_DEV_URL;#combining-multiple-versions-library-files-into-one-image'>Multilib</ulink>
                    configuration.
                </para>

                <para>
                    To add a tune to the list, be sure to append it with
                    spaces using the "+=" BitBake operator.
                    Do not simply replace the list by using the "=" operator.
                    See the
                    "<ulink url='&YOCTO_DOCS_BB_URL;#basic-syntax'>Basic Syntax</ulink>"
                    section in the BitBake User Manual for more information.
                </para>
            </glossdef>
        </glossentry>


    </glossdiv>

    <glossdiv id='var-glossary-b'><title>B</title>

        <glossentry id='var-B'><glossterm>B</glossterm>
            <glossdef>
                <para>
                    The directory within the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>
                    in which the OpenEmbedded build system places generated
                    objects during a recipe's build process.
                    By default, this directory is the same as the <link linkend='var-S'><filename>S</filename></link>
                    directory, which is defined as:
                    <literallayout class='monospaced'>
     S = "${WORKDIR}/${BP}/"
                    </literallayout>
                    You can separate the (<filename>S</filename>) directory
                    and the directory pointed to by the <filename>B</filename>
                    variable.
                    Most Autotools-based recipes support separating these
                    directories.
                    The build system defaults to using separate directories for
                    <filename>gcc</filename> and some kernel recipes.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BAD_RECOMMENDATIONS'><glossterm>BAD_RECOMMENDATIONS</glossterm>
            <glossdef>
                <para>
                    Lists "recommended-only" packages to not install.
                    Recommended-only packages are packages installed only
                    through the
                    <link linkend='var-RRECOMMENDS'><filename>RRECOMMENDS</filename></link>
                    variable.
                    You can prevent any of these "recommended" packages from
                    being installed by listing them with the
                    <filename>BAD_RECOMMENDATIONS</filename> variable:
                    <literallayout class='monospaced'>
     BAD_RECOMMENDATIONS = "<replaceable>package_name</replaceable> <replaceable>package_name</replaceable> <replaceable>package_name</replaceable> ..."
                    </literallayout>
                    You can set this variable globally in your
                    <filename>local.conf</filename> file or you can attach it to
                    a specific image recipe by using the recipe name override:
                    <literallayout class='monospaced'>
     BAD_RECOMMENDATIONS_pn-<replaceable>target_image</replaceable> = "<replaceable>package_name</replaceable>"
                    </literallayout>
                </para>

                <para>
                    It is important to realize that if you choose to not install
                    packages using this variable and some other packages are
                    dependent on them (i.e. listed in a recipe's
                    <link linkend='var-RDEPENDS'><filename>RDEPENDS</filename></link>
                    variable), the OpenEmbedded build system ignores your
                    request and will install the packages to avoid dependency
                    errors.
                </para>

                <para>
                    Support for this variable exists only when using the
                    IPK and RPM packaging backend.
                    Support does not exist for DEB.
                </para>

                <para>
                    See the
                    <link linkend='var-NO_RECOMMENDATIONS'><filename>NO_RECOMMENDATIONS</filename></link>
                    and the
                    <link linkend='var-PACKAGE_EXCLUDE'><filename>PACKAGE_EXCLUDE</filename></link>
                    variables for related information.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BASE_LIB'><glossterm>BASE_LIB</glossterm>
            <glossdef>
                <para>
                    The library directory name for the CPU or Application
                    Binary Interface (ABI) tune.
                    The <filename>BASE_LIB</filename> applies only in the
                    Multilib context.
                    See the
                    "<ulink url='&YOCTO_DOCS_DEV_URL;#combining-multiple-versions-library-files-into-one-image'>Combining Multiple Versions of Library Files into One Image</ulink>"
                    section in the Yocto Project Development Manual for
                    information on Multilib.
                </para>

                <para>
                    The <filename>BASE_LIB</filename> variable is defined in
                    the machine include files in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>.
                    If Multilib is not being used, the value defaults to "lib".
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BB_DANGLINGAPPENDS_WARNONLY'><glossterm>BB_DANGLINGAPPENDS_WARNONLY</glossterm>
            <glossdef>
                <para>
                    Defines how BitBake handles situations where an append
                    file (<filename>.bbappend</filename>) has no
                    corresponding recipe file (<filename>.bb</filename>).
                    This condition often occurs when layers get out of sync
                    (e.g. <filename>oe-core</filename> bumps a
                    recipe version and the old recipe no longer exists and the
                    other layer has not been updated to the new version
                    of the recipe yet).
                </para>

                <para>
                    The default fatal behavior is safest because it is
                    the sane reaction given something is out of sync.
                    It is important to realize when your changes are no longer
                    being applied.
                </para>

                <para>
                    You can change the default behavior by setting this
                    variable to "1", "yes", or "true"
                    in your <filename>local.conf</filename> file, which is
                    located in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>:
                    Here is an example:
                    <literallayout class='monospaced'>
     BB_DANGLINGAPPENDS_WARNONLY = "1"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BB_DISKMON_DIRS'><glossterm>BB_DISKMON_DIRS</glossterm>
            <glossdef>
                <para>
                    Monitors disk space and available inodes during the build
                    and allows you to control the build based on these
                    parameters.
                </para>

                <para>
                    Disk space monitoring is disabled by default.
                    To enable monitoring, add the <filename>BB_DISKMON_DIRS</filename>
                    variable to your <filename>conf/local.conf</filename> file found in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
                    Use the following form:
                    <literallayout class='monospaced'>
     BB_DISKMON_DIRS = "<replaceable>action</replaceable>,<replaceable>dir</replaceable>,<replaceable>threshold</replaceable> [...]"

     where:

        <replaceable>action</replaceable> is:
           ABORT:     Immediately abort the build when
                      a threshold is broken.
           STOPTASKS: Stop the build after the currently
                      executing tasks have finished when
                      a threshold is broken.
           WARN:      Issue a warning but continue the
                      build when a threshold is broken.
                      Subsequent warnings are issued as
                      defined by the
                      <link linkend='var-BB_DISKMON_WARNINTERVAL'>BB_DISKMON_WARNINTERVAL</link> variable,
                      which must be defined in the
                      conf/local.conf file.

        <replaceable>dir</replaceable> is:
           Any directory you choose. You can specify one or
           more directories to monitor by separating the
           groupings with a space.  If two directories are
           on the same device, only the first directory
           is monitored.

        <replaceable>threshold</replaceable> is:
           Either the minimum available disk space,
           the minimum number of free inodes, or
           both.  You must specify at least one.  To
           omit one or the other, simply omit the value.
           Specify the threshold using G, M, K for Gbytes,
           Mbytes, and Kbytes, respectively. If you do
           not specify G, M, or K, Kbytes is assumed by
           default.  Do not use GB, MB, or KB.
                    </literallayout>
                </para>

                <para>
                    Here are some examples:
                    <literallayout class='monospaced'>
     BB_DISKMON_DIRS = "ABORT,${TMPDIR},1G,100K WARN,${SSTATE_DIR},1G,100K"
     BB_DISKMON_DIRS = "STOPTASKS,${TMPDIR},1G"
     BB_DISKMON_DIRS = "ABORT,${TMPDIR},,100K"
                    </literallayout>
                    The first example works only if you also provide
                    the <link linkend='var-BB_DISKMON_WARNINTERVAL'><filename>BB_DISKMON_WARNINTERVAL</filename></link> variable
                    in the <filename>conf/local.conf</filename>.
                    This example causes the build system to immediately
                    abort when either the disk space in <filename>${TMPDIR}</filename> drops
                    below 1 Gbyte or the available free inodes drops below
                    100 Kbytes.
                    Because two directories are provided with the variable, the
                    build system also issue a
                    warning when the disk space in the
                    <filename>${SSTATE_DIR}</filename> directory drops
                    below 1 Gbyte or the number of free inodes drops
                    below 100 Kbytes.
                    Subsequent warnings are issued during intervals as
                    defined by the <filename>BB_DISKMON_WARNINTERVAL</filename>
                    variable.
                </para>

                <para>
                    The second example stops the build after all currently
                    executing tasks complete when the minimum disk space
                    in the <filename>${<link linkend='var-TMPDIR'>TMPDIR</link>}</filename>
                    directory drops below 1 Gbyte.
                    No disk monitoring occurs for the free inodes in this case.
                </para>

                <para>
                    The final example immediately aborts the build when the
                    number of free inodes in the <filename>${TMPDIR}</filename> directory
                    drops below 100 Kbytes.
                    No disk space monitoring for the directory itself occurs
                    in this case.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BB_DISKMON_WARNINTERVAL'><glossterm>BB_DISKMON_WARNINTERVAL</glossterm>
            <glossdef>
                <para>
                    Defines the disk space and free inode warning intervals.
                    To set these intervals, define the variable in your
                    <filename>conf/local.conf</filename> file in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
                </para>

                <para>
                    If you are going to use the
                    <filename>BB_DISKMON_WARNINTERVAL</filename> variable, you must
                    also use the
                    <link linkend='var-BB_DISKMON_DIRS'><filename>BB_DISKMON_DIRS</filename></link> variable
                    and define its action as "WARN".
                    During the build, subsequent warnings are issued each time
                    disk space or number of free inodes further reduces by
                    the respective interval.
                </para>

                <para>
                    If you do not provide a <filename>BB_DISKMON_WARNINTERVAL</filename>
                    variable and you do use <filename>BB_DISKMON_DIRS</filename> with
                    the "WARN" action, the disk monitoring interval defaults to
                    the following:
                    <literallayout class='monospaced'>
     BB_DISKMON_WARNINTERVAL = "50M,5K"
                    </literallayout>
                </para>

                <para>
                    When specifying the variable in your configuration file,
                    use the following form:
                    <literallayout class='monospaced'>
     BB_DISKMON_WARNINTERVAL = "<replaceable>disk_space_interval</replaceable>,<replaceable>disk_inode_interval</replaceable>"

     where:

        <replaceable>disk_space_interval</replaceable> is:
           An interval of memory expressed in either
           G, M, or K for Gbytes, Mbytes, or Kbytes,
           respectively. You cannot use GB, MB, or KB.

        <replaceable>disk_inode_interval</replaceable> is:
           An interval of free inodes expressed in either
           G, M, or K for Gbytes, Mbytes, or Kbytes,
           respectively. You cannot use GB, MB, or KB.
                    </literallayout>
                </para>

                <para>
                    Here is an example:
                    <literallayout class='monospaced'>
     BB_DISKMON_DIRS = "WARN,${SSTATE_DIR},1G,100K"
     BB_DISKMON_WARNINTERVAL = "50M,5K"
                    </literallayout>
                    These variables cause the OpenEmbedded build system to
                    issue subsequent warnings each time the available
                    disk space further reduces by 50 Mbytes or the number
                    of free inodes further reduces by 5 Kbytes in the
                    <filename>${SSTATE_DIR}</filename> directory.
                    Subsequent warnings based on the interval occur each time
                    a respective interval is reached beyond the initial warning
                    (i.e. 1 Gbytes and 100 Kbytes).
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BB_GENERATE_MIRROR_TARBALLS'><glossterm>BB_GENERATE_MIRROR_TARBALLS</glossterm>
            <glossdef>
                <para>
                    Causes tarballs of the Git repositories, including the
                    Git metadata, to be placed in the
                    <link linkend='var-DL_DIR'><filename>DL_DIR</filename></link>
                    directory.
                </para>

                <para>
                    For performance reasons, creating and placing tarballs of
                    the Git repositories is not the default action by the
                    OpenEmbedded build system.
                    <literallayout class='monospaced'>
     BB_GENERATE_MIRROR_TARBALLS = "1"
                    </literallayout>
                    Set this variable in your <filename>local.conf</filename>
                    file in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BB_NUMBER_THREADS'><glossterm>BB_NUMBER_THREADS</glossterm>
            <glossdef>
                <para>
                    The maximum number of tasks BitBake should run in parallel
                    at any one time.
                    If your host development system supports multiple cores,
                    a good rule of thumb is to set this variable to twice the
                    number of cores.
                </para>

                <para>
                    The default value for <filename>BB_NUMBER_THREADS</filename>
                    is equal to the number of cores your build system has.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BBCLASSEXTEND'><glossterm>BBCLASSEXTEND</glossterm>
            <glossdef>
                <para>
                    Allows you to extend a recipe so that it builds variants of the software.
                    Common variants for recipes exist such as "natives" like <filename>quilt-native</filename>,
                    which is a copy of Quilt built to run on the build system;
                    "crosses" such as <filename>gcc-cross</filename>,
                    which is a compiler built to run on the build machine but produces binaries
                    that run on the target <link linkend='var-MACHINE'><filename>MACHINE</filename></link>;
                    "nativesdk", which targets the SDK machine instead of <filename>MACHINE</filename>;
                    and "mulitlibs" in the form "<filename>multilib:</filename><replaceable>multilib_name</replaceable>".
                </para>

                <para>
                    To build a different variant of the recipe with a minimal amount of code, it usually
                    is as simple as adding the following to your recipe:
                    <literallayout class='monospaced'>
     BBCLASSEXTEND =+ "native nativesdk"
     BBCLASSEXTEND =+ "multilib:<replaceable>multilib_name</replaceable>"
                    </literallayout>
                </para>
             </glossdef>
        </glossentry>

        <glossentry id='var-BBFILE_COLLECTIONS'><glossterm>BBFILE_COLLECTIONS</glossterm>
            <glossdef>
                <para>Lists the names of configured layers.
                    These names are used to find the other <filename>BBFILE_*</filename>
                    variables.
                    Typically, each layer will append its name to this variable in its
                    <filename>conf/layer.conf</filename> file.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BBFILE_PATTERN'><glossterm>BBFILE_PATTERN</glossterm>
            <glossdef>
                <para>Variable that expands to match files from
                    <link linkend='var-BBFILES'><filename>BBFILES</filename></link>
                    in a particular layer.
                    This variable is used in the <filename>conf/layer.conf</filename> file and must
                    be suffixed with the name of the specific layer (e.g.
                    <filename>BBFILE_PATTERN_emenlow</filename>).</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BBFILE_PRIORITY'><glossterm>BBFILE_PRIORITY</glossterm>
            <glossdef>
                <para>Assigns the priority for recipe files in each layer.</para>
                <para>This variable is useful in situations where the same recipe appears in
                    more than one layer.
                    Setting this variable allows you to prioritize a
                    layer against other layers that contain the same recipe - effectively
                    letting you control the precedence for the multiple layers.
                    The precedence established through this variable stands regardless of a
                    recipe's version
                    (<link linkend='var-PV'><filename>PV</filename></link> variable).
                    For example, a layer that has a recipe with a higher <filename>PV</filename> value but for
                    which the <filename>BBFILE_PRIORITY</filename> is set to have a lower precedence still has a
                    lower precedence.</para>
                <para>A larger value for the <filename>BBFILE_PRIORITY</filename> variable results in a higher
                    precedence.
                    For example, the value 6 has a higher precedence than the value 5.
                    If not specified, the <filename>BBFILE_PRIORITY</filename> variable is set based on layer
                    dependencies (see the
                    <filename><link linkend='var-LAYERDEPENDS'>LAYERDEPENDS</link></filename> variable for
                    more information.
                    The default priority, if unspecified
                    for a layer with no dependencies, is the lowest defined priority + 1
                    (or 1 if no priorities are defined).</para>
                <tip>
                    You can use the command <filename>bitbake-layers show-layers</filename> to list
                    all configured layers along with their priorities.
                </tip>
            </glossdef>
        </glossentry>

        <glossentry id='var-BBFILES'><glossterm>BBFILES</glossterm>
            <glossdef>
                <para>List of recipe files used by BitBake to build software.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BBINCLUDELOGS'><glossterm>BBINCLUDELOGS</glossterm>
            <glossdef>
                <para>Variable that controls how BitBake displays logs on build failure.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BBLAYERS'><glossterm>BBLAYERS</glossterm>
            <glossdef>
                <para>Lists the layers to enable during the build.
                    This variable is defined in the <filename>bblayers.conf</filename> configuration
                    file in the <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
                    Here is an example:
                    <literallayout class='monospaced'>
     BBLAYERS = " \
       /home/scottrif/poky/meta \
       /home/scottrif/poky/meta-yocto \
       /home/scottrif/poky/meta-yocto-bsp \
       /home/scottrif/poky/meta-mykernel \
       "

     BBLAYERS_NON_REMOVABLE ?= " \
       /home/scottrif/poky/meta \
       /home/scottrif/poky/meta-yocto \
       "
                    </literallayout>
                    This example enables four layers, one of which is a custom, user-defined layer
                    named <filename>meta-mykernel</filename>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BBLAYERS_NON_REMOVABLE'><glossterm>BBLAYERS_NON_REMOVABLE</glossterm>
            <glossdef>
                <para>Lists core layers that cannot be removed from the
                    <filename>bblayers.conf</filename> file during a build
                    using the
                    <ulink url='https://www.yoctoproject.org/tools-resources/projects/hob'>Hob</ulink>.
                    <note>
                        When building an image outside of Hob, this variable
                        is ignored.
                    </note>
                    In order for BitBake to build your image using Hob, your
                    <filename>bblayers.conf</filename> file must include the
                    <filename>meta</filename> and <filename>meta-yocto</filename>
                    core layers.
                    Here is an example that shows these two layers listed in
                    the <filename>BBLAYERS_NON_REMOVABLE</filename> statement:
                    <literallayout class='monospaced'>
     BBLAYERS = " \
       /home/scottrif/poky/meta \
       /home/scottrif/poky/meta-yocto \
       /home/scottrif/poky/meta-yocto-bsp \
       /home/scottrif/poky/meta-mykernel \
       "

     BBLAYERS_NON_REMOVABLE ?= " \
       /home/scottrif/poky/meta \
       /home/scottrif/poky/meta-yocto \
       "
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BBMASK'><glossterm>BBMASK</glossterm>
            <glossdef>
                <para>
                    Prevents BitBake from processing recipes and recipe
                    append files.
                    Use the <filename>BBMASK</filename> variable from within the
                    <filename>conf/local.conf</filename> file found
                    in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
                </para>

                <para>
                    You can use the <filename>BBMASK</filename> variable
                    to "hide" these <filename>.bb</filename> and
                    <filename>.bbappend</filename> files.
                    BitBake ignores any recipe or recipe append files that
                    match the expression.
                    It is as if BitBake does not see them at all.
                    Consequently, matching files are not parsed or otherwise
                    used by BitBake.</para>
                <para>
                    The value you provide is passed to Python's regular
                    expression compiler.
                    The expression is compared against the full paths to
                    the files.
                    For complete syntax information, see Python's
                    documentation at
                    <ulink url='http://docs.python.org/release/2.3/lib/re-syntax.html'></ulink>.
                </para>

                <para>
                    The following example uses a complete regular expression
                    to tell BitBake to ignore all recipe and recipe append
                    files in the <filename>meta-ti/recipes-misc/</filename>
                    directory:
                    <literallayout class='monospaced'>
     BBMASK = "meta-ti/recipes-misc/"
                    </literallayout>
                    If you want to mask out multiple directories or recipes,
                    use the vertical bar to separate the regular expression
                    fragments.
                    This next example masks out multiple directories and
                    individual recipes:
                    <literallayout class='monospaced'>
     BBMASK = "meta-ti/recipes-misc/|meta-ti/recipes-ti/packagegroup/"
     BBMASK .= "|.*meta-oe/recipes-support/"
     BBMASK .= "|.*openldap"
     BBMASK .= "|.*opencv"
     BBMASK .= "|.*lzma"
                    </literallayout>
                    Notice how the vertical bar is used to append the fragments.
                    <note>
                        When specifying a directory name, use the trailing
                        slash character to ensure you match just that directory
                        name.
                    </note>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BBPATH'><glossterm>BBPATH</glossterm>
            <glossdef>
                <para>
                    Used by BitBake to locate
                    <filename>.bbclass</filename> and configuration files.
                    This variable is analogous to the
                    <filename>PATH</filename> variable.
                    <note>
                        If you run BitBake from a directory outside of the
                        <ulink url='&YOCTO_DOCS_DEV_URL;build-directory'>Build Directory</ulink>,
                        you must be sure to set
                        <filename>BBPATH</filename> to point to the
                        Build Directory.
                        Set the variable as you would any environment variable
                        and then run BitBake:
                        <literallayout class='monospaced'>
     $ BBPATH = "<replaceable>build_directory</replaceable>"
     $ export BBPATH
     $ bitbake <replaceable>target</replaceable>
                        </literallayout>
                    </note>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BBSERVER'><glossterm>BBSERVER</glossterm>
            <glossdef>
                <para>
                    Points to the server that runs memory-resident BitBake.
                    This variable is set by the
                    <link linkend='structure-memres-core-script'><filename>oe-init-build-env-memres</filename></link>
                    setup script and should not be hand-edited.
                    The variable is only used when you employ memory-resident
                    BitBake.
                    The setup script exports the value as follows:
                    <literallayout class='monospaced'>
     export BBSERVER=localhost:$port
                    </literallayout>
                    For more information on how the
                    <filename>BBSERVER</filename> is used, see the
                    <filename>oe-init-build-env-memres</filename> script, which
                    is located in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BINCONFIG'><glossterm>BINCONFIG</glossterm>
            <glossdef>
                <para>
                    When inheriting the
                    <link linkend='ref-classes-binconfig-disabled'><filename>binconfig-disabled</filename></link>
                    class, this variable specifies binary configuration
                    scripts to disable in favor of using
                    <filename>pkg-config</filename> to query the information.
                    The <filename>binconfig-disabled</filename> class will
                    modify the specified scripts to return an error so that
                    calls to them can be easily found and replaced.
                </para>

                <para>
                    To add multiple scripts, separate them by spaces.
                    Here is an example from the <filename>libpng</filename>
                    recipe:
                    <literallayout class='monospaced'>
     BINCONFIG = "${bindir}/libpng-config ${bindir}/libpng16-config"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BINCONFIG_GLOB'><glossterm>BINCONFIG_GLOB</glossterm>
            <glossdef>
                <para>
                    When inheriting the
                    <link linkend='ref-classes-binconfig'><filename>binconfig</filename></link>
                    class, this variable specifies a wildcard for
                    configuration scripts that need editing.
                    The scripts are edited to correct any paths that have been
                    set up during compilation so that they are correct for
                    use when installed into the sysroot and called by the
                    build processes of other recipes.
                </para>

                <para>
                    For more information on how this variable works, see
                    <filename>meta/classes/binconfig.bbclass</filename> in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>.
                    You can also find general information on the class in the
                    "<link linkend='ref-classes-binconfig'><filename>binconfig.bbclass</filename></link>"
                    section.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BP'><glossterm>BP</glossterm>
            <glossdef>
                <para>The base recipe name and version but without any special
                    recipe name suffix (i.e. <filename>-native</filename>, <filename>lib64-</filename>,
                    and so forth).
                    <filename>BP</filename> is comprised of the following:
                    <literallayout class="monospaced">
     ${BPN}-${PV}
                    </literallayout></para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BPN'><glossterm>BPN</glossterm>
            <glossdef>
                <para>The bare name of the recipe.
                    This variable is a version of the <link linkend='var-PN'><filename>PN</filename></link> variable
                    but removes common suffixes such as "-native" and "-cross" as well
                    as removes common prefixes such as multilib's "lib64-" and "lib32-".
                    The exact list of suffixes removed is specified by the
                    <link linkend='var-SPECIAL_PKGSUFFIX'><filename>SPECIAL_PKGSUFFIX</filename></link> variable.
                    The exact list of prefixes removed is specified by the
                    <link linkend='var-MLPREFIX'><filename>MLPREFIX</filename></link> variable.
                    Prefixes are removed for <filename>multilib</filename>
                    and <filename>nativesdk</filename> cases.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BUGTRACKER'><glossterm>BUGTRACKER</glossterm>
            <glossdef>
                <para>
                    Specifies a URL for an upstream bug tracking website for
                    a recipe.
                    The OpenEmbedded build system does not use this variable.
                    Rather, the variable is a useful pointer in case a bug
                    in the software being built needs to be manually reported.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BUILD_CFLAGS'><glossterm>BUILD_CFLAGS</glossterm>
            <glossdef>
                <para>
                    Specifies the flags to pass to the C compiler when building
                    for the build host.
                    When building in the <filename>-native</filename> context,
                    <link linkend='var-CFLAGS'><filename>CFLAGS</filename></link>
                    is set to the value of this variable by default.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BUILD_CPPFLAGS'><glossterm>BUILD_CPPFLAGS</glossterm>
            <glossdef>
                <para>
                    Specifies the flags to pass to the C pre-processor
                    (i.e. to both the C and the C++ compilers) when building
                    for the build host.
                    When building in the <filename>native</filename> context,
                    <link linkend='var-CPPFLAGS'><filename>CPPFLAGS</filename></link>
                    is set to the value of this variable by default.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BUILD_CXXFLAGS'><glossterm>BUILD_CXXFLAGS</glossterm>
            <glossdef>
                <para>
                    Specifies the flags to pass to the C++ compiler when
                    building for the build host.
                    When building in the <filename>native</filename> context,
                    <link linkend='var-CXXFLAGS'><filename>CXXFLAGS</filename></link>
                    is set to the value of this variable by default.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BUILD_LDFLAGS'><glossterm>BUILD_LDFLAGS</glossterm>
            <glossdef>
                <para>
                    Specifies the flags to pass to the linker when building
                    for the build host.
                    When building in the <filename>-native</filename> context,
                    <link linkend='var-LDFLAGS'><filename>LDFLAGS</filename></link>
                    is set to the value of this variable by default.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BUILD_OPTIMIZATION'><glossterm>BUILD_OPTIMIZATION</glossterm>
            <glossdef>
                <para>
                    Specifies the optimization flags passed to the C compiler
                    when building for the build host or the SDK.
                    The flags are passed through the
                    <link linkend='var-BUILD_CFLAGS'><filename>BUILD_CFLAGS</filename></link>
                    and
                    <link linkend='var-BUILDSDK_CFLAGS'><filename>BUILDSDK_CFLAGS</filename></link>
                    default values.
                </para>

                <para>
                    The default value of the
                    <filename>BUILD_OPTIMIZATION</filename> variable is
                    "-O2 -pipe".
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BUILDDIR'><glossterm>BUILDDIR</glossterm>
            <glossdef>
                <para>
                    Points to the location of the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
                    You can define this directory indirectly through the
                    <link linkend='structure-core-script'><filename>&OE_INIT_FILE;</filename></link>
                    and
                    <link linkend='structure-memres-core-script'><filename>oe-init-build-env-memres</filename></link>
                    scripts by passing in a Build Directory path when you run
                    the scripts.
                    If you run the scripts and do not provide a Build Directory
                    path, the <filename>BUILDDIR</filename> defaults to
                    <filename>build</filename> in the current directory.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BUILDHISTORY_COMMIT'><glossterm>BUILDHISTORY_COMMIT</glossterm>
            <glossdef>
                <para>
                    When inheriting the
                    <link linkend='ref-classes-buildhistory'><filename>buildhistory</filename></link>
                    class, this variable specifies whether or not to commit the
                    build history output in a local Git repository.
                    If set to "1", this local repository will be maintained
                    automatically by the
                    <filename>buildhistory</filename>
                    class and a commit will be created on every
                    build for changes to each top-level subdirectory of the
                    build history output (images, packages, and sdk).
                    If you want to track changes to build history over
                    time, you should set this value to "1".
                </para>

                <para>
                    By default, the <filename>buildhistory</filename> class
                    does not commit the build history output in a local
                    Git repository:
                    <literallayout class='monospaced'>
     BUILDHISTORY_COMMIT ?= "0"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BUILDHISTORY_COMMIT_AUTHOR'><glossterm>BUILDHISTORY_COMMIT_AUTHOR</glossterm>
            <glossdef>
                <para>
                    When inheriting the
                    <link linkend='ref-classes-buildhistory'><filename>buildhistory</filename></link>
                    class, this variable specifies the author to use for each
                    Git commit.
                    In order for the <filename>BUILDHISTORY_COMMIT_AUTHOR</filename>
                    variable to work, the
                    <link linkend='var-BUILDHISTORY_COMMIT'><filename>BUILDHISTORY_COMMIT</filename></link>
                    variable must be set to "1".
                </para>

                <para>
                    Git requires that the value you provide for the
                    <filename>BUILDHISTORY_COMMIT_AUTHOR</filename> variable
                    takes the form of "name &lt;email@host&gt;".
                    Providing an email address or host that is not valid does
                    not produce an error.
                </para>

                <para>
                    By default, the <filename>buildhistory</filename> class
                    sets the variable as follows:
                    <literallayout class='monospaced'>
     BUILDHISTORY_COMMIT_AUTHOR ?= "buildhistory &lt;buildhistory@${DISTRO}&gt;"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BUILDHISTORY_DIR'><glossterm>BUILDHISTORY_DIR</glossterm>
            <glossdef>
                <para>
                    When inheriting the
                    <link linkend='ref-classes-buildhistory'><filename>buildhistory</filename></link>
                    class, this variable specifies the directory in which
                    build history information is kept.
                    For more information on how the variable works, see the
                    <filename>buildhistory.class</filename>.
                </para>

                <para>
                    By default, the <filename>buildhistory</filename> class
                    sets the directory as follows:
                    <literallayout class='monospaced'>
     BUILDHISTORY_DIR ?= "${TOPDIR}/buildhistory"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BUILDHISTORY_FEATURES'><glossterm>BUILDHISTORY_FEATURES</glossterm>
            <glossdef>
                <para>
                    When inheriting the
                    <link linkend='ref-classes-buildhistory'><filename>buildhistory</filename></link>
                    class, this variable specifies the build history features
                    to be enabled.
                    For more information on how build history works, see the
                    "<link linkend='maintaining-build-output-quality'>Maintaining Build Output Quality</link>"
                    section.
                </para>

                <para>
                    You can specify three features in the form of a
                    space-separated list:
                    <itemizedlist>
                        <listitem><para><emphasis>image:</emphasis>
                            Analysis of the contents of images, which
                            includes the list of installed packages among other
                            things.
                            </para></listitem>
                        <listitem><para><emphasis>package:</emphasis>
                            Analysis of the contents of individual packages.
                            </para></listitem>
                        <listitem><para><emphasis>sdk:</emphasis>
                            Analysis of the contents of the software
                            development kit (SDK).
                            </para></listitem>
                    </itemizedlist>
                </para>

                <para>
                    By default, the <filename>buildhistory</filename> class
                    enables all three features:
                    <literallayout class='monospaced'>
     BUILDHISTORY_FEATURES ?= "image package sdk"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BUILDHISTORY_IMAGE_FILES'><glossterm>BUILDHISTORY_IMAGE_FILES</glossterm>
            <glossdef>
                <para>
                    When inheriting the
                    <link linkend='ref-classes-buildhistory'><filename>buildhistory</filename></link>
                    class, this variable specifies a list of paths to files
                    copied from the
                    image contents into the build history directory under
                    an "image-files" directory in the directory for
                    the image, so that you can track the contents of each file.
                    The default is to copy <filename>/etc/passwd</filename>
                    and <filename>/etc/group</filename>, which allows you to
                    monitor for changes in user and group entries.
                    You can modify the list to include any file.
                    Specifying an invalid path does not produce an error.
                    Consequently, you can include files that might
                    not always be present.
                </para>

                <para>
                    By default, the <filename>buildhistory</filename> class
                    provides paths to the following files:
                    <literallayout class='monospaced'>
     BUILDHISTORY_IMAGE_FILES ?= "/etc/passwd /etc/group"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BUILDHISTORY_PUSH_REPO'><glossterm>BUILDHISTORY_PUSH_REPO</glossterm>
            <glossdef>
                <para>
                    When inheriting the
                    <link linkend='ref-classes-buildhistory'><filename>buildhistory</filename></link>
                    class, this variable optionally specifies a remote
                    repository to which build history pushes Git changes.
                    In order for <filename>BUILDHISTORY_PUSH_REPO</filename>
                    to work,
                    <link linkend='var-BUILDHISTORY_COMMIT'><filename>BUILDHISTORY_COMMIT</filename></link>
                    must be set to "1".
                </para>

                <para>
                    The repository should correspond to a remote
                    address that specifies a repository as understood by
                    Git, or alternatively to a remote name that you have
                    set up manually using <filename>git remote</filename>
                    within the local repository.
                </para>

                <para>
                    By default, the <filename>buildhistory</filename> class
                    sets the variable as follows:
                    <literallayout class='monospaced'>
     BUILDHISTORY_PUSH_REPO ?= ""
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BUILDSDK_CFLAGS'><glossterm>BUILDSDK_CFLAGS</glossterm>
            <glossdef>
                <para>
                    Specifies the flags to pass to the C compiler when building
                    for the SDK.
                    When building in the <filename>nativesdk</filename>
                    context,
                    <link linkend='var-CFLAGS'><filename>CFLAGS</filename></link>
                    is set to the value of this variable by default.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BUILDSDK_CPPFLAGS'><glossterm>BUILDSDK_CPPFLAGS</glossterm>
            <glossdef>
                <para>
                    Specifies the flags to pass to the C pre-processor
                    (i.e. to both the C and the C++ compilers) when building
                    for the SDK.
                    When building in the <filename>nativesdk</filename>
                    context,
                    <link linkend='var-CPPFLAGS'><filename>CPPFLAGS</filename></link>
                    is set to the value of this variable by default.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BUILDSDK_CXXFLAGS'><glossterm>BUILDSDK_CXXFLAGS</glossterm>
            <glossdef>
                <para>
                    Specifies the flags to pass to the C++ compiler when
                    building for the SDK.
                    When building in the <filename>nativesdk</filename>
                    context,
                    <link linkend='var-CXXFLAGS'><filename>CXXFLAGS</filename></link>
                    is set to the value of this variable by default.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BUILDSDK_LDFLAGS'><glossterm>BUILDSDK_LDFLAGS</glossterm>
            <glossdef>
                <para>
                    Specifies the flags to pass to the linker when building
                    for the SDK.
                    When building in the <filename>nativesdk-</filename>
                    context,
                    <link linkend='var-LDFLAGS'><filename>LDFLAGS</filename></link>
                    is set to the value of this variable by default.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BUILDSTATS_BASE'><glossterm>BUILDSTATS_BASE</glossterm>
            <glossdef>
                <para>
                    Points to the location of the directory that holds build
                    statistics when you use and enable the
                    <link linkend='ref-classes-buildstats'><filename>buildstats</filename></link>
                    class.
                    The <filename>BUILDSTATS_BASE</filename> directory defaults
                    to
                    <filename>${</filename><link linkend='var-TMPDIR'><filename>TMPDIR</filename></link><filename>}/buildstats/</filename>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-BUSYBOX_SPLIT_SUID'><glossterm>BUSYBOX_SPLIT_SUID</glossterm>
            <glossdef>
                <para>
                    For the BusyBox recipe, specifies whether to split the
                    output executable file into two parts: one for features
                    that require <filename>setuid root</filename>, and one for
                    the remaining features (i.e. those that do not require
                    <filename>setuid root</filename>).
                </para>

                <para>
                    The <filename>BUSYBOX_SPLIT_SUID</filename> variable
                    defaults to "1", which results in a single output
                    executable file.
                    Set the variable to "0" to split the output file.
                </para>
            </glossdef>
        </glossentry>

    </glossdiv>

    <glossdiv id='var-glossary-c'><title>C</title>

        <glossentry id='var-CFLAGS'><glossterm>CFLAGS</glossterm>
            <glossdef>
                <para>
                    Specifies the flags to pass to the C compiler.
                    This variable is exported to an environment
                    variable and thus made visible to the software being
                    built during the compilation step.
                </para>

                <para>
                    Default initialization for <filename>CFLAGS</filename>
                    varies depending on what is being built:
                    <itemizedlist>
                        <listitem><para>
                            <link linkend='var-TARGET_CFLAGS'><filename>TARGET_CFLAGS</filename></link>
                            when building for the target
                            </para></listitem>
                        <listitem><para>
                            <link linkend='var-BUILD_CFLAGS'><filename>BUILD_CFLAGS</filename></link>
                            when building for the build host (i.e.
                            <filename>-native</filename>)
                            </para></listitem>
                        <listitem><para>
                            <link linkend='var-BUILDSDK_CFLAGS'><filename>BUILDSDK_CFLAGS</filename></link>
                            when building for an SDK (i.e.
                            <filename>nativesdk-</filename>)
                            </para></listitem>
                    </itemizedlist>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-CLASSOVERRIDE'><glossterm>CLASSOVERRIDE</glossterm>
            <glossdef>
                <para>
                    An internal variable specifying the special class override
                    that should currently apply (e.g. "class-target",
                    "class-native", and so forth).
                    The classes that use this variable set it to
                    appropriate values.
                </para>

                <para>
                    You do not normally directly interact with this variable.
                    The value for the <filename>CLASSOVERRIDE</filename>
                    variable goes into
                    <link linkend='var-OVERRIDES'><filename>OVERRIDES</filename></link>
                    and then can be used as an override.
                    Here is an example where "python-native" is added to
                    <link linkend='var-DEPENDS'><filename>DEPENDS</filename></link>
                    only when building for the native case:
                    <literallayout class='monospaced'>
     DEPENDS_append_class-native = " python-native"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-COMBINED_FEATURES'><glossterm>COMBINED_FEATURES</glossterm>
            <glossdef>
                <para>
                    Provides a list of hardware features that are enabled in
                    both
                    <link linkend='var-MACHINE_FEATURES'><filename>MACHINE_FEATURES</filename></link>
                    and
                    <link linkend='var-DISTRO_FEATURES'><filename>DISTRO_FEATURES</filename></link>.
                    This select list of features contains features that make
                    sense to be controlled both at the machine and distribution
                    configuration level.
                    For example, the "bluetooth" feature requires hardware
                    support but should also be optional at the distribution
                    level, in case the hardware supports Bluetooth but you
                    do not ever intend to use it.
                </para>

                <para>
                    For more information, see the
                    <link linkend='var-MACHINE_FEATURES'><filename>MACHINE_FEATURES</filename></link>
                    and <link linkend='var-DISTRO_FEATURES'><filename>DISTRO_FEATURES</filename></link>
                    variables.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-COMMON_LICENSE_DIR'><glossterm>COMMON_LICENSE_DIR</glossterm>
            <glossdef>
                <para>
                    Points to <filename>meta/files/common-licenses</filename>
                    in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>,
                    which is where generic license files reside.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-COMPATIBLE_HOST'><glossterm>COMPATIBLE_HOST</glossterm>
            <glossdef>
                <para>A regular expression that resolves to one or more hosts
                    (when the recipe is native) or one or more targets (when
                    the recipe is non-native) with which a recipe is compatible.
                    The regular expression is matched against
                    <link linkend="var-HOST_SYS"><filename>HOST_SYS</filename></link>.
                    You can use the variable to stop recipes from being built
                    for classes of systems with which the recipes are not
                    compatible.
                    Stopping these builds is particularly useful with kernels.
                    The variable also helps to increase parsing speed
                    since the build system skips parsing recipes not
                    compatible with the current system.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-COMPATIBLE_MACHINE'><glossterm>COMPATIBLE_MACHINE</glossterm>
            <glossdef>
                <para>A regular expression that resolves to one or more
                    target machines with which a recipe is compatible.
                    The regular expression is matched against
                    <link linkend="var-MACHINEOVERRIDES"><filename>MACHINEOVERRIDES</filename></link>.
                    You can use the variable to stop recipes from being built
                    for machines with which the recipes are not compatible.
                    Stopping these builds is particularly useful with kernels.
                    The variable also helps to increase parsing speed
                    since the build system skips parsing recipes not
                    compatible with the current machine.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-COMPLEMENTARY_GLOB'><glossterm>COMPLEMENTARY_GLOB</glossterm>
            <glossdef>
                <para>
                    Defines wildcards to match when installing a list of
                    complementary packages for all the packages explicitly
                    (or implicitly) installed in an image.
                    The resulting list of complementary packages is associated
                    with an item that can be added to
                    <link linkend='var-IMAGE_FEATURES'><filename>IMAGE_FEATURES</filename></link>.
                    An example usage of this is the "dev-pkgs" item that when
                    added to <filename>IMAGE_FEATURES</filename> will
                    install -dev packages (containing headers and other
                    development files) for every package in the image.
                </para>

                <para>
                    To add a new feature item pointing to a wildcard, use a
                    variable flag to specify the feature item name and
                    use the value to specify the wildcard.
                    Here is an example:
                    <literallayout class='monospaced'>
     COMPLEMENTARY_GLOB[dev-pkgs] = '*-dev'
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-CONFFILES'><glossterm>CONFFILES</glossterm>
            <glossdef>
                <para>
                    Identifies editable or configurable files that are part of a package.
                    If the Package Management System (PMS) is being used to update
                    packages on the target system, it is possible that
                    configuration files you have changed after the original installation
                    and that you now want to remain unchanged are overwritten.
                    In other words, editable files might exist in the package that you do not
                    want reset as part of the package update process.
                    You can use the <filename>CONFFILES</filename> variable to list the files in the
                    package that you wish to prevent the PMS from overwriting during this update process.
                </para>

                <para>
                    To use the <filename>CONFFILES</filename> variable, provide a package name
                    override that identifies the resulting package.
                    Then, provide a space-separated list of files.
                    Here is an example:
                    <literallayout class='monospaced'>
     CONFFILES_${PN} += "${sysconfdir}/file1 \
        ${sysconfdir}/file2 ${sysconfdir}/file3"
                    </literallayout>
                </para>

                <para>
                    A relationship exists between the <filename>CONFFILES</filename> and
                    <filename><link linkend='var-FILES'>FILES</link></filename> variables.
                    The files listed within <filename>CONFFILES</filename> must be a subset of
                    the files listed within <filename>FILES</filename>.
                    Because the configuration files you provide with <filename>CONFFILES</filename>
                    are simply being identified so that the PMS will not overwrite them,
                    it makes sense that
                    the files must already be included as part of the package through the
                    <filename>FILES</filename> variable.
                </para>

                <note>
                    When specifying paths as part of the <filename>CONFFILES</filename> variable,
                    it is good practice to use appropriate path variables.
                    For example, <filename>${sysconfdir}</filename> rather than
                    <filename>/etc</filename> or <filename>${bindir}</filename> rather
                    than <filename>/usr/bin</filename>.
                    You can find a list of these variables at the top of the
                    <filename>meta/conf/bitbake.conf</filename> file in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>.
                </note>
            </glossdef>
        </glossentry>

        <glossentry id='var-CONFIG_INITRAMFS_SOURCE'><glossterm>CONFIG_INITRAMFS_SOURCE</glossterm>
            <glossdef>
                <para>
                    Identifies the initial RAM disk (initramfs) source files.
                    The OpenEmbedded build system receives and uses
                    this kernel Kconfig variable as an environment variable.
                    By default, the variable is set to null ("").
                </para>

                <para>
                    The <filename>CONFIG_INITRAMFS_SOURCE</filename> can be
                    either a single cpio archive with a
                    <filename>.cpio</filename> suffix or a
                    space-separated list of directories and files for building
                    the initramfs image.
                    A cpio archive should contain a filesystem archive
                    to be used as an initramfs image.
                    Directories should contain a filesystem layout to be
                    included in the initramfs image.
                    Files should contain entries according to the format
                    described by the
                    <filename>usr/gen_init_cpio</filename> program in the
                    kernel tree.
                </para>

                <para>
                    If you specify multiple directories and files, the
                    initramfs image will be the aggregate of all of them.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-CONFIG_SITE'><glossterm>CONFIG_SITE</glossterm>
            <glossdef>
                <para>
                    A list of files that contains <filename>autoconf</filename> test results relevant
                    to the current build.
                    This variable is used by the Autotools utilities when running
                    <filename>configure</filename>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-CONFLICT_DISTRO_FEATURES'><glossterm>CONFLICT_DISTRO_FEATURES</glossterm>
            <glossdef>
                <para>
                    When inheriting the
                    <link linkend='ref-classes-distro_features_check'><filename>distro_features_check</filename></link>
                    class, this
                    variable identifies distribution features that would
                    be in conflict should the recipe
                    be built.
                    In other words, if the
                    <filename>CONFLICT_DISTRO_FEATURES</filename> variable
                    lists a feature that also appears in
                    <filename>DISTRO_FEATURES</filename> within the
                    current configuration, an error occurs and the
                    build stops.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-COPY_LIC_DIRS'><glossterm>COPY_LIC_DIRS</glossterm>
            <glossdef>
                <para>
                    If set to "1" along with the
                    <link linkend='var-COPY_LIC_MANIFEST'><filename>COPY_LIC_MANIFEST</filename></link>
                    variable, the OpenEmbedded build system copies
                    into the image the license files, which are located in
                    <filename>/usr/share/common-licenses</filename>,
                    for each package.
                    The license files are placed
                    in directories within the image itself.
                    </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-COPY_LIC_MANIFEST'><glossterm>COPY_LIC_MANIFEST</glossterm>
            <glossdef>
                <para>
                    If set to "1", the OpenEmbedded build system copies
                    the license manifest for the image to
                    <filename>/usr/share/common-licenses/license.manifest</filename>
                    within the image itself.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-CORE_IMAGE_EXTRA_INSTALL'><glossterm>CORE_IMAGE_EXTRA_INSTALL</glossterm>
            <glossdef>
                <para>
                    Specifies the list of packages to be added to the image.
                    You should only set this variable in the
                    <filename>local.conf</filename> configuration file found
                    in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
                </para>

                <para>
                    This variable replaces <filename>POKY_EXTRA_INSTALL</filename>, which is no longer supported.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-COREBASE'><glossterm>COREBASE</glossterm>
            <glossdef>
                <para>
                    Specifies the parent directory of the OpenEmbedded
                    Core Metadata layer (i.e. <filename>meta</filename>).
                </para>

                <para>
                    It is an important distinction that
                    <filename>COREBASE</filename> points to the parent of this
                    layer and not the layer itself.
                    Consider an example where you have cloned the Poky Git
                    repository and retained the <filename>poky</filename>
                    name for your local copy of the repository.
                    In this case, <filename>COREBASE</filename> points to
                    the <filename>poky</filename> folder because it is the
                    parent directory of the <filename>poky/meta</filename>
                    layer.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-CPPFLAGS'><glossterm>CPPFLAGS</glossterm>
            <glossdef>
                <para>
                    Specifies the flags to pass to the C pre-processor
                    (i.e. to both the C and the C++ compilers).
                    This variable is exported to an environment
                    variable and thus made visible to the software being
                    built during the compilation step.
                </para>

                <para>
                    Default initialization for <filename>CPPFLAGS</filename>
                    varies depending on what is being built:
                    <itemizedlist>
                        <listitem><para>
                            <link linkend='var-TARGET_CPPFLAGS'><filename>TARGET_CPPFLAGS</filename></link>
                            when building for the target
                            </para></listitem>
                        <listitem><para>
                            <link linkend='var-BUILD_CPPFLAGS'><filename>BUILD_CPPFLAGS</filename></link>
                            when building for the build host (i.e.
                            <filename>-native</filename>)
                            </para></listitem>
                        <listitem><para>
                            <link linkend='var-BUILDSDK_CPPFLAGS'><filename>BUILDSDK_CPPFLAGS</filename></link>
                            when building for an SDK (i.e.
                            <filename>nativesdk-</filename>)
                            </para></listitem>
                    </itemizedlist>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-CXXFLAGS'><glossterm>CXXFLAGS</glossterm>
            <glossdef>
                <para>
                    Specifies the flags to pass to the C++ compiler.
                    This variable is exported to an environment
                    variable and thus made visible to the software being
                    built during the compilation step.
                </para>

                <para>
                    Default initialization for <filename>CXXFLAGS</filename>
                    varies depending on what is being built:
                    <itemizedlist>
                        <listitem><para>
                            <link linkend='var-TARGET_CXXFLAGS'><filename>TARGET_CXXFLAGS</filename></link>
                            when building for the target
                            </para></listitem>
                        <listitem><para>
                            <link linkend='var-BUILD_CXXFLAGS'><filename>BUILD_CXXFLAGS</filename></link>
                            when building for the build host (i.e.
                            <filename>-native</filename>)
                            </para></listitem>
                        <listitem><para>
                            <link linkend='var-BUILDSDK_CXXFLAGS'><filename>BUILDSDK_CXXFLAGS</filename></link>
                            when building for an SDK (i.e.
                            <filename>nativesdk</filename>)
                            </para></listitem>
                    </itemizedlist>
                </para>
            </glossdef>
        </glossentry>

    </glossdiv>

    <glossdiv id='var-glossary-d'><title>D</title>

        <glossentry id='var-D'><glossterm>D</glossterm>
            <glossdef>
                <para>
                    The destination directory.
                    The location in the <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>
                    where components are installed by the
                    <link linkend='ref-tasks-install'><filename>do_install</filename></link>
                    task.
                    This location defaults to:
                    <literallayout class='monospaced'>
     ${WORKDIR}/image
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DATETIME'><glossterm>DATETIME</glossterm>
            <glossdef>
                <para>
                    The date and time on which the current build started.
                    The format is suitable for timestamps.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DEBUG_BUILD'><glossterm>DEBUG_BUILD</glossterm>
            <glossdef>
                <para>
                    Specifies to build packages with debugging information.
                    This influences the value of the
                    <filename><link linkend='var-SELECTED_OPTIMIZATION'>SELECTED_OPTIMIZATION</link></filename>
                    variable.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DEBUG_OPTIMIZATION'><glossterm>DEBUG_OPTIMIZATION</glossterm>
            <glossdef>
                <para>
                    The options to pass in
                    <filename><link linkend='var-TARGET_CFLAGS'>TARGET_CFLAGS</link></filename>
                    and <filename><link linkend='var-CFLAGS'>CFLAGS</link></filename> when compiling
                    a system for debugging.
                    This variable defaults to "-O -fno-omit-frame-pointer ${DEBUG_FLAGS} -pipe".
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DEFAULT_PREFERENCE'><glossterm>DEFAULT_PREFERENCE</glossterm>
            <glossdef>
                <para>
                    Specifies a weak bias for recipe selection priority.
                </para>
                <para>
                    The most common usage of this is variable is to set
                    it to "-1" within a recipe for a development version of a
                    piece of software.
                    Using the variable in this way causes the stable version
                    of the recipe to build by default in the absence of
                    <filename><link linkend='var-PREFERRED_VERSION'>PREFERRED_VERSION</link></filename>
                    being used to build the development version.
                </para>
                <note>
                    The bias provided by <filename>DEFAULT_PREFERENCE</filename>
                    is weak and is overridden by
                    <filename><link linkend='var-BBFILE_PRIORITY'>BBFILE_PRIORITY</link></filename>
                    if that variable is different between two layers
                    that contain different versions of the same recipe.
                </note>
            </glossdef>
        </glossentry>

        <glossentry id='var-DEFAULTTUNE'><glossterm>DEFAULTTUNE</glossterm>
            <glossdef>
                <para>
                    The default CPU and Application Binary Interface (ABI)
                    tunings (i.e.  the "tune") used by the OpenEmbedded build
                    system.
                    The <filename>DEFAULTTUNE</filename> helps define
                    <link linkend='var-TUNE_FEATURES'><filename>TUNE_FEATURES</filename></link>.
                </para>

                <para>
                    The default tune is either implicitly or explicitly set
                    by the machine
                    (<link linkend='var-MACHINE'><filename>MACHINE</filename></link>).
                    However, you can override the setting using available tunes
                    as defined with
                    <link linkend='var-AVAILTUNES'><filename>AVAILTUNES</filename></link>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DEPENDS'><glossterm>DEPENDS</glossterm>
            <glossdef>
                <para>
                    Lists a recipe's build-time dependencies
                    (i.e. other recipe files).
                    The system ensures that all the dependencies listed
                    have been built and have their contents in the appropriate
                    sysroots before the recipe's configure task is executed.
                </para>

                <para>
                    Consider this simple example for two recipes named "a" and
                    "b" that produce similarly named packages.
                    In this example, the <filename>DEPENDS</filename>
                    statement appears in the "a" recipe:
                    <literallayout class='monospaced'>
     DEPENDS = "b"
                    </literallayout>
                    Here, the dependency is such that the
                    <link linkend='ref-tasks-configure'><filename>do_configure</filename></link>
                    task for recipe "a" depends on the
                    <link linkend='ref-tasks-populate_sysroot'><filename>do_populate_sysroot</filename></link>
                    task of recipe "b".
                    This means anything that recipe "b" puts into sysroot
                    is available when recipe "a" is configuring itself.
                </para>

                <para>
                    For information on runtime dependencies, see the
                    <link linkend='var-RDEPENDS'><filename>RDEPENDS</filename></link>
                    variable.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DEPLOY_DIR'><glossterm>DEPLOY_DIR</glossterm>
            <glossdef>
                <para>
                    Points to the general area that the OpenEmbedded build
                    system uses to place images, packages, SDKs and other output
                    files that are ready to be used outside of the build system.
                    By default, this directory resides within the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>
                    as <filename>${TMPDIR}/deploy</filename>.
                </para>

                <para>
                    For more information on the structure of the Build
                    Directory, see
                    "<link linkend='structure-build'>The Build Directory - <filename>build/</filename></link>"
                    section.
                    For more detail on the contents of the
                    <filename>deploy</filename> directory, see the
                    "<link linkend='images-dev-environment'>Images</link>" and
                    "<link linkend='sdk-dev-environment'>Application Development SDK</link>"
                    sections.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DEPLOY_DIR_IMAGE'><glossterm>DEPLOY_DIR_IMAGE</glossterm>
            <glossdef>
                <para>
                    Points to the area that the OpenEmbedded build system uses
                    to place images and other associated output files that are
                    ready to be deployed onto the target machine.
                    The directory is machine-specific as it contains the
                    <filename>${MACHINE}</filename> name.
                    By default, this directory resides within the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>
                    as <filename>${DEPLOY_DIR}/images/${MACHINE}/</filename>.
                </para>

                <para>
                    For more information on the structure of the Build
                    Directory, see
                    "<link linkend='structure-build'>The Build Directory - <filename>build/</filename></link>"
                    section.
                    For more detail on the contents of the
                    <filename>deploy</filename> directory, see the
                    "<link linkend='images-dev-environment'>Images</link>" and
                    "<link linkend='sdk-dev-environment'>Application Development SDK</link>"
                    sections.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DEPLOYDIR'><glossterm>DEPLOYDIR</glossterm>
            <glossdef>
                <para>
                    When inheriting the
                    <link linkend='ref-classes-deploy'><filename>deploy</filename></link>
                    class, the <filename>DEPLOYDIR</filename> points to a
                    temporary work area for deployed files that is set in the
                    <filename>deploy</filename> class as follows:
                    <literallayout class='monospaced'>
     DEPLOYDIR = "${WORKDIR}/deploy-${<link linkend='var-PN'><filename>PN</filename></link>}"
                    </literallayout>
                    Recipes inheriting the <filename>deploy</filename> class
                    should copy files to be deployed into
                    <filename>DEPLOYDIR</filename>, and the class will take
                    care of copying them into
                    <link linkend='var-DEPLOY_DIR_IMAGE'><filename>DEPLOY_DIR_IMAGE</filename></link>
                    afterwards.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DESCRIPTION'><glossterm>DESCRIPTION</glossterm>
            <glossdef>
                <para>The package description used by package managers.
                      If not set, <filename>DESCRIPTION</filename> takes
                      the value of the
                      <link linkend='var-SUMMARY'><filename>SUMMARY</filename></link>
                      variable.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DISK_SIGNATURE'><glossterm>DISK_SIGNATURE</glossterm>
            <glossdef>
                <para>
                    A 32-bit MBR disk signature used by
                    <filename>directdisk</filename> images.
                </para>

                <para>
                    By default, the signature is set to an automatically
                    generated random value that allows the OpenEmbedded
                    build system to create a boot loader.
                    You can override the signature in the image recipe
                    by setting <filename>DISK_SIGNATURE</filename> to an
                    8-digit hex string.
                    You might want to override
                    <filename>DISK_SIGNATURE</filename> if you want the disk
                    signature to remain constant between image builds.
                </para>

                <para>
                    When using Linux 3.8 or later, you can use
                    <filename>DISK_SIGNATURE</filename> to specify the root
                    by UUID to allow the kernel to locate the root device
                    even if the device name changes due to differences in
                    hardware configuration.
                    By default, <filename>SYSLINUX_ROOT</filename> is set
                    as follows:
                    <literallayout class='monospaced'>
     SYSLINUX_ROOT = "root=/dev/sda2"
                    </literallayout>
                    However, you can change this to locate the root device
                    using the disk signature instead:
                    <literallayout class='monospaced'>
     SYSLINUX_ROOT = "root=PARTUUID=${DISK_SIGNATURE}-02"
                    </literallayout>
                </para>

                <para>
                    As previously mentioned, it is possible to set the
                    <filename>DISK_SIGNATURE</filename> variable in your
                    <filename>local.conf</filename> file to a fixed
                    value if you do not want <filename>syslinux.cfg</filename>
                    changing for each build.
                    You might find this useful when you want to upgrade the
                    root filesystem on a device without having to recreate or
                    modify the master boot record.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DISTRO'><glossterm>DISTRO</glossterm>
            <glossdef>
                <para>
                    The short name of the distribution.
                    This variable corresponds to a distribution
                    configuration file whose root name is the same as the
                    variable's argument and whose filename extension is
                    <filename>.conf</filename>.
                    For example, the distribution configuration file for the
                    Poky distribution is named <filename>poky.conf</filename>
                    and resides in the
                    <filename>meta-yocto/conf/distro</filename> directory of
                    the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>.
                </para>

                <para>
                    Within that <filename>poky.conf</filename> file, the
                    <filename>DISTRO</filename> variable is set as follows:
                    <literallayout class='monospaced'>
     DISTRO = "poky"
                    </literallayout>
                </para>

                <para>
                    Distribution configuration files are located in a
                    <filename>conf/distro</filename> directory within the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#metadata'>Metadata</ulink>
                    that contains the distribution configuration.
                    The value for <filename>DISTRO</filename> must not contain
                    spaces, and is typically all lower-case.
                    <note>
                        If the <filename>DISTRO</filename> variable is blank, a set
                        of default configurations are used, which are specified
                        within
                        <filename>meta/conf/distro/defaultsetup.conf</filename>
                        also in the Source Directory.
                    </note>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DISTRO_EXTRA_RDEPENDS'><glossterm>DISTRO_EXTRA_RDEPENDS</glossterm>
            <glossdef>
                <para>
                    Specifies a list of distro-specific packages to add to all images.
                    This variable takes affect through
                    <filename>packagegroup-base</filename> so the
                    variable only really applies to the more full-featured
                    images that include <filename>packagegroup-base</filename>.
                    You can use this variable to keep distro policy out of
                    generic images.
                    As with all other distro variables, you set this variable
                    in the distro <filename>.conf</filename> file.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DISTRO_EXTRA_RRECOMMENDS'><glossterm>DISTRO_EXTRA_RRECOMMENDS</glossterm>
            <glossdef>
                <para>
                    Specifies a list of distro-specific packages to add to all images
                    if the packages exist.
                    The packages might not exist or be empty (e.g. kernel modules).
                    The list of packages are automatically installed but you can
                    remove them.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DISTRO_FEATURES'><glossterm>DISTRO_FEATURES</glossterm>
            <glossdef>
                <para>
                    The software support you want in your distribution for
                    various features.
                    You define your distribution features in the distribution
                    configuration file.
                </para>

                <para>
                    In most cases, the presence or absence of a feature in
                    <filename>DISTRO_FEATURES</filename> is translated to the
                    appropriate option supplied to the configure script
                    during the
                    <link linkend='ref-tasks-configure'><filename>do_configure</filename></link>
                    task for recipes that optionally support the feature.
                    For example, specifying "x11" in
                    <filename>DISTRO_FEATURES</filename>, causes
                    every piece of software built for the target that can
                    optionally support X11 to have its X11 support enabled.
                </para>

                <para>
                    Two more examples are Bluetooth and NFS support.
                    For a more complete list of features that ships with the
                    Yocto Project and that you can provide with this variable,
                    see the
                    "<link linkend='ref-features-distro'>Distro Features</link>"
                    section.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DISTRO_FEATURES_BACKFILL'><glossterm>DISTRO_FEATURES_BACKFILL</glossterm>
            <glossdef>
                <para>Features to be added to
                    <filename><link linkend='var-DISTRO_FEATURES'>DISTRO_FEATURES</link></filename>
                    if not also present in
                    <filename><link linkend='var-DISTRO_FEATURES_BACKFILL_CONSIDERED'>DISTRO_FEATURES_BACKFILL_CONSIDERED</link></filename>.
                </para>

                <para>
                    This variable is set in the <filename>meta/conf/bitbake.conf</filename> file.
                    It is not intended to be user-configurable.
                    It is best to just reference the variable to see which distro features are
                    being backfilled for all distro configurations.
                    See the <link linkend='ref-features-backfill'>Feature backfilling</link> section for
                    more information.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DISTRO_FEATURES_BACKFILL_CONSIDERED'><glossterm>DISTRO_FEATURES_BACKFILL_CONSIDERED</glossterm>
            <glossdef>
                <para>Features from
                    <filename><link linkend='var-DISTRO_FEATURES_BACKFILL'>DISTRO_FEATURES_BACKFILL</link></filename>
                    that should not be backfilled (i.e. added to
                    <filename><link linkend='var-DISTRO_FEATURES'>DISTRO_FEATURES</link></filename>)
                    during the build.
                    See the "<link linkend='ref-features-backfill'>Feature Backfilling</link>" section for
                    more information.
                    </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DISTRO_NAME'><glossterm>DISTRO_NAME</glossterm>
            <glossdef>
                <para>The long name of the distribution.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DISTRO_PN_ALIAS'><glossterm>DISTRO_PN_ALIAS</glossterm>
            <glossdef>
                <para>Alias names used for the recipe in various Linux distributions.</para>
                <para>See the
                    "<ulink url='&YOCTO_DOCS_DEV_URL;#usingpoky-configuring-DISTRO_PN_ALIAS'>Handling
                    a Package Name Alias</ulink>" section in the Yocto Project Development
                    Manual for more information.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DISTRO_VERSION'><glossterm>DISTRO_VERSION</glossterm>
            <glossdef>
                <para>The version of the distribution.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DISTROOVERRIDES'><glossterm>DISTROOVERRIDES</glossterm>
            <glossdef>
                <para>
                    This variable lists overrides specific to the current
                    distribution.
                    By default, the variable list includes the value of the
                    <filename><link linkend='var-DISTRO'>DISTRO</link></filename>
                    variable.
                    You can extend the variable to apply any variable overrides
                    you want as part of the distribution and are not
                    already in <filename>OVERRIDES</filename> through
                    some other means.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DL_DIR'><glossterm>DL_DIR</glossterm>
            <glossdef>
                <para>
                    The central download directory used by the build process to
                    store downloads.
                    By default, <filename>DL_DIR</filename> gets files
                    suitable for mirroring for everything except Git
                    repositories.
                    If you want tarballs of Git repositories, use the
                    <link linkend='var-BB_GENERATE_MIRROR_TARBALLS'><filename>BB_GENERATE_MIRROR_TARBALLS</filename></link>
                    variable.
                </para>

                <para>
                    You can set this directory by defining the
                    <filename>DL_DIR</filename> variable in the
                    <filename>conf/local.conf</filename> file.
                    This directory is self-maintaining and you should not have
                    to touch it.
                    By default, the directory is <filename>downloads</filename>
                    in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
                    <literallayout class='monospaced'>
     #DL_DIR ?= "${TOPDIR}/downloads"
                    </literallayout>
                    To specify a different download directory, simply remove
                    the comment from the line and provide your directory.
                </para>

                <para>
                    During a first build, the system downloads many different
                    source code tarballs from various upstream projects.
                    Downloading can take a while, particularly if your network
                    connection is slow.
                    Tarballs are all stored in the directory defined by
                    <filename>DL_DIR</filename> and the build system looks there
                    first to find source tarballs.
                    <note>
                        When wiping and rebuilding, you can preserve this
                        directory to speed up this part of subsequent
                        builds.
                    </note>
                </para>

                <para>
                    You can safely share this directory between multiple builds
                    on the same development machine.
                    For additional information on how the build process gets
                    source files when working behind a firewall or proxy server,
                    see this specific question in the
                    "<link linkend='how-does-the-yocto-project-obtain-source-code-and-will-it-work-behind-my-firewall-or-proxy-server'>FAQ</link>"
                    chapter.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-DOC_COMPRESS'><glossterm>DOC_COMPRESS</glossterm>
            <glossdef>
                <para>
                    When inheriting the
                    <link linkend='ref-classes-compress_doc'><filename>compress_doc</filename></link>
                    class, this variable sets the compression policy used when
                    the OpenEmbedded build system compresses man pages and info
                    pages.
                    By default, the compression method used is gz (gzip).
                    Other policies available are xz and bz2.
                </para>

                <para>
                    For information on policies and on how to use this
                    variable, see the comments in the
                    <filename>meta/classes/compress_doc.bbclass</filename> file.
                </para>
            </glossdef>
        </glossentry>

    </glossdiv>

    <glossdiv id='var-glossary-e'><title>E</title>

        <glossentry id='var-EFI_PROVIDER'><glossterm>EFI_PROVIDER</glossterm>
            <glossdef>
                <para>
                    When building bootable images (i.e. where
                    <filename>hddimg</filename> or <filename>vmdk</filename>
                    is in
                    <link linkend='var-IMAGE_FSTYPES'><filename>IMAGE_FSTYPES</filename></link>),
                    The <filename>EFI_PROVIDER</filename> variable specifies
                    the EFI bootloader to use.
                    The default is "grub-efi", but "gummiboot" can be used
                    instead.
                </para>

                <para>
                    See the
                    <link linkend='ref-classes-gummiboot'><filename>gummiboot</filename></link>
                    class for more information.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-ENABLE_BINARY_LOCALE_GENERATION'><glossterm>ENABLE_BINARY_LOCALE_GENERATION</glossterm>
            <glossdef>
                <para>Variable that controls which locales for
                    <filename>glibc</filename> are generated during the
                    build (useful if the target device has 64Mbytes
                    of RAM or less).</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-ERROR_QA'><glossterm>ERROR_QA</glossterm>
            <glossdef>
                <para>
                    Specifies the quality assurance checks whose failures are
                    reported as errors by the OpenEmbedded build system.
                    You set this variable in your distribution configuration
                    file.
                    For a list of the checks you can control with this variable,
                    see the
                    "<link linkend='ref-classes-insane'><filename>insane.bbclass</filename></link>"
                    section.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-ERR_REPORT_DIR'><glossterm>ERR_REPORT_DIR</glossterm>
            <glossdef>
                <para>
                    When used with the
                    <link linkend='ref-classes-report-error'><filename>report-error</filename></link>
                    class, specifies the path used for storing the debug files
                    created by the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#using-the-error-reporting-tool'>error reporting tool</ulink>,
                    which allows you to submit build errors you encounter to a
                    central database.
                    By default, the value of this variable is
                    <filename>${</filename><link linkend='var-LOG_DIR'><filename>LOG_DIR</filename></link><filename>}/error-report</filename>.
                </para>

                <para>
                    You can set <filename>ERR_REPORT_DIR</filename> to the path
                    you want the error reporting tool to store the debug files
                    as follows in your <filename>local.conf</filename> file:
                    <literallayout class='monospaced'>
     ERR_REPORT_DIR = "<replaceable>path</replaceable>"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-EXCLUDE_FROM_WORLD'><glossterm>EXCLUDE_FROM_WORLD</glossterm>
            <glossdef>
                <para>
                    Directs BitBake to exclude a recipe from world builds (i.e.
                    <filename>bitbake world</filename>).
                    During world builds, BitBake locates, parses and builds all
                    recipes found in every layer exposed in the
                    <filename>bblayers.conf</filename> configuration file.
                </para>

                <para>
                    To exclude a recipe from a world build using this variable,
                    set the variable to "1" in the recipe.
                </para>

                <note>
                    Recipes added to <filename>EXCLUDE_FROM_WORLD</filename>
                    may still be built during a world build in order to satisfy
                    dependencies of other recipes.
                    Adding a recipe to <filename>EXCLUDE_FROM_WORLD</filename>
                    only ensures that the recipe is not explicitly added
                    to the list of build targets in a world build.
                </note>
            </glossdef>
        </glossentry>

        <glossentry id='var-EXTENDPE'><glossterm>EXTENDPE</glossterm>
            <glossdef>
                <para>
                    Used with file and pathnames to create a prefix for a recipe's
                    version based on the recipe's
                    <link linkend='var-PE'><filename>PE</filename></link> value.
                    If <filename>PE</filename> is set and greater than zero for a recipe,
                    <filename>EXTENDPE</filename> becomes that value (e.g if
                    <filename>PE</filename> is equal to "1" then <filename>EXTENDPE</filename>
                    becomes "1_").
                    If a recipe's <filename>PE</filename> is not set (the default) or is equal to
                    zero, <filename>EXTENDPE</filename> becomes "".</para>
                    <para>See the <link linkend='var-STAMP'><filename>STAMP</filename></link>
                    variable for an example.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-EXTENDPKGV'><glossterm>EXTENDPKGV</glossterm>
            <glossdef>
                <para>
                    The full package version specification as it appears on the
                    final packages produced by a recipe.
                    The variable's value is normally used to fix a runtime
                    dependency to the exact same version of another package
                    in the same recipe:
                    <literallayout class='monospaced'>
     RDEPENDS_${PN}-additional-module = "${PN} (= ${EXTENDPKGV})"
                    </literallayout>
                </para>

                <para>
                    The dependency relationships are intended to force the
                    package manager to upgrade these types of packages in
                    lock-step.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-EXTERNALSRC'><glossterm>EXTERNALSRC</glossterm>
            <glossdef>
                <para>
                    When inheriting the
                    <link linkend='ref-classes-externalsrc'><filename>externalsrc</filename></link>
                    class, this variable points to the source tree, which is
                    outside of the OpenEmbedded build system.
                    When set, this variable sets the
                    <link linkend='var-S'><filename>S</filename></link>
                    variable, which is what the OpenEmbedded build system uses
                    to locate unpacked recipe source code.
                </para>

                <para>
                    For more information on
                    <filename>externalsrc.bbclass</filename>, see the
                    "<link linkend='ref-classes-externalsrc'><filename>externalsrc.bbclass</filename></link>"
                    section.
                    You can also find information on how to use this variable
                    in the
                    "<ulink url='&YOCTO_DOCS_DEV_URL;#building-software-from-an-external-source'>Building Software from an External Source</ulink>"
                    section in the Yocto Project Development Manual.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-EXTERNALSRC_BUILD'><glossterm>EXTERNALSRC_BUILD</glossterm>
            <glossdef>
                <para>
                    When inheriting the
                    <link linkend='ref-classes-externalsrc'><filename>externalsrc</filename></link>
                    class, this variable points to the directory in which the
                    recipe's source code is built, which is outside of the
                    OpenEmbedded build system.
                    When set, this variable sets the
                    <link linkend='var-B'><filename>B</filename></link>
                    variable, which is what the OpenEmbedded build system uses
                    to locate the Build Directory.
                </para>

                <para>
                    For more information on
                    <filename>externalsrc.bbclass</filename>, see the
                    "<link linkend='ref-classes-externalsrc'><filename>externalsrc.bbclass</filename></link>"
                    section.
                    You can also find information on how to use this variable
                    in the
                    "<ulink url='&YOCTO_DOCS_DEV_URL;#building-software-from-an-external-source'>Building Software from an External Source</ulink>"
                    section in the Yocto Project Development Manual.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-EXTRA_IMAGE_FEATURES'><glossterm>EXTRA_IMAGE_FEATURES</glossterm>
            <glossdef>
                <para>
                    The list of additional features to include in an image.
                    Typically, you configure this variable in your
                    <filename>local.conf</filename> file, which is found in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
                    Although you can use this variable from within a recipe,
                    best practices dictate that you do not.
                    <note>
                        To enable primary features from within the image
                        recipe, use the
                        <link linkend='var-IMAGE_FEATURES'><filename>IMAGE_FEATURES</filename></link>
                        variable.
                    </note>
                </para>

                <para>
                    Here are some examples of features you can add:
                    <literallayout class='monospaced'>
"dbg-pkgs" - Adds -dbg packages for all installed packages
             including symbol information for debugging and
             profiling.

"debug-tweaks" - Makes an image suitable for development.
                 For example, ssh root access has a blank
                 password.  You should remove this feature
                 before you produce a production image.

"dev-pkgs" - Adds -dev packages for all installed packages.
             This is useful if you want to develop against
             the libraries in the image.

"read-only-rootfs" - Creates an image whose root
                     filesystem is read-only. See the
                     "<ulink url='&YOCTO_DOCS_DEV_URL;#creating-a-read-only-root-filesystem'>Creating a Read-Only Root Filesystem</ulink>"
                     section in the Yocto Project
                     Development Manual for more
                     information

"tools-debug" - Adds debugging tools such as gdb and
                strace.

"tools-profile" - Adds profiling tools such as oprofile,
                  exmap, lttng and valgrind (x86 only).

"tools-sdk" - Adds development tools such as gcc, make,
              pkgconfig and so forth.

"tools-testapps" - Adds useful testing tools such as
                   ts_print, aplay, arecord and so
                   forth.

                    </literallayout>
                </para>

                <para>
                    For a complete list of image features that ships with the
                    Yocto Project, see the
                    "<link linkend="ref-features-image">Image Features</link>"
                    section.
                </para>

                <para>
                    For an example that shows how to customize your image by
                    using this variable, see the
                    "<ulink url='&YOCTO_DOCS_DEV_URL;#usingpoky-extend-customimage-imagefeatures'>Customizing Images Using Custom <filename>IMAGE_FEATURES</filename> and <filename>EXTRA_IMAGE_FEATURES</filename></ulink>"
                    section in the Yocto Project Development Manual.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-EXTRA_IMAGECMD'><glossterm>EXTRA_IMAGECMD</glossterm>
            <glossdef>
                <para>
                    Specifies additional options for the image
                    creation command that has been specified in
                    <link linkend='var-IMAGE_CMD'><filename>IMAGE_CMD</filename></link>.
                    When setting this variable, you should
                    use an override for the associated type.
                    Here is an example:
                    <literallayout class='monospaced'>
     EXTRA_IMAGECMD_ext3 ?= "-i 4096"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-EXTRA_IMAGEDEPENDS'><glossterm>EXTRA_IMAGEDEPENDS</glossterm>
            <glossdef>
                <para>A list of recipes to build that do not provide packages
                    for installing into the root filesystem.
                </para>
                <para>Sometimes a recipe is required to build the final image but is not
                    needed in the root filesystem.
                    You can use the <filename>EXTRA_IMAGEDEPENDS</filename> variable to
                    list these recipes and thus specify the dependencies.
                    A typical example is a required bootloader in a machine configuration.
                </para>
                <note>
                    To add packages to the root filesystem, see the various
                    <filename>*<link linkend='var-RDEPENDS'>RDEPENDS</link></filename>
                    and <filename>*<link linkend='var-RRECOMMENDS'>RRECOMMENDS</link></filename>
                    variables.
                </note>
            </glossdef>
        </glossentry>

        <glossentry id='var-EXTRA_OECMAKE'><glossterm>EXTRA_OECMAKE</glossterm>
            <glossdef>
                <para>Additional <filename>cmake</filename> options.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-EXTRA_OECONF'><glossterm>EXTRA_OECONF</glossterm>
            <glossdef>
                <para>Additional <filename>configure</filename> script options.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-EXTRA_OEMAKE'><glossterm>EXTRA_OEMAKE</glossterm>
            <glossdef>
                <para>Additional GNU <filename>make</filename> options.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-EXTRA_OESCONS'><glossterm>EXTRA_OESCONS</glossterm>
            <glossdef>
                <para>
                    When inheriting the
                    <link linkend='ref-classes-scons'><filename>scons</filename></link>
                    class, this variable specifies additional configuration
                    options you want to pass to the
                    <filename>scons</filename> command line.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-EXTRA_QMAKEVARS_POST'><glossterm>EXTRA_QMAKEVARS_POST</glossterm>
            <glossdef>
                <para>
                    Configuration variables or options you want to pass to
                    <filename>qmake</filename>.
                    Use this variable when the arguments need to be after the
                    <filename>.pro</filename> file list on the command line.
                </para>

                <para>
                    This variable is used with recipes that inherit the
                    <link linkend='ref-classes-qmake*'><filename>qmake_base</filename></link>
                    class or other classes that inherit
                    <filename>qmake_base</filename>.
                </para>
            </glossdef>
        </glossentry>

       <glossentry id='var-EXTRA_QMAKEVARS_PRE'><glossterm>EXTRA_QMAKEVARS_PRE</glossterm>
            <glossdef>
                <para>
                    Configuration variables or options you want to pass to
                    <filename>qmake</filename>.
                    Use this variable when the arguments need to be before the
                    <filename>.pro</filename> file list on the command line.
                </para>

                <para>
                    This variable is used with recipes that inherit the
                    <link linkend='ref-classes-qmake*'><filename>qmake_base</filename></link>
                    class or other classes that inherit
                    <filename>qmake_base</filename>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-EXTRA_USERS_PARAMS'><glossterm>EXTRA_USERS_PARAMS</glossterm>
            <glossdef>
                <para>
                    When inheriting the
                    <link linkend='ref-classes-extrausers'><filename>extrausers</filename></link>
                    class, this variable provides image level user and group
                    operations.
                    This is a more global method of providing user and group
                    configuration as compared to using the
                    <link linkend='ref-classes-useradd'><filename>useradd</filename></link>
                    class, which ties user and group configurations to a
                    specific recipe.
                </para>

                <para>
                    The set list of commands you can configure using the
                    <filename>EXTRA_USERS_PARAMS</filename> is shown in the
                    <filename>extrausers</filename> class.
                    These commands map to the normal Unix commands of the same
                    names:
                    <literallayout class='monospaced'>
     # EXTRA_USERS_PARAMS = "\
     # useradd -p '' tester; \
     # groupadd developers; \
     # userdel nobody; \
     # groupdel -g video; \
     # groupmod -g 1020 developers; \
     # usermod -s /bin/sh tester; \
     # "
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

    </glossdiv>

    <glossdiv id='var-glossary-f'><title>F</title>

        <glossentry id='var-FEATURE_PACKAGES'><glossterm>FEATURE_PACKAGES</glossterm>
            <glossdef>
                <para>
                    Defines one or more packages to include in an image when
                    a specific item is included in
                    <link linkend='var-IMAGE_FEATURES'><filename>IMAGE_FEATURES</filename></link>.
                    When setting the value, <filename>FEATURE_PACKAGES</filename>
                    should have the name of the feature item as an override.
                    Here is an example:
                    <literallayout class='monospaced'>
     FEATURE_PACKAGES_widget = "<replaceable>package1</replaceable> <replaceable>package2</replaceable>"
                    </literallayout>
                    In this example, if "widget" were added to
                    <filename>IMAGE_FEATURES</filename>, <replaceable>package1</replaceable> and
                    <replaceable>package2</replaceable> would be included in the image.
                    <note>
                        Packages installed by features defined through
                        <filename>FEATURE_PACKAGES</filename> are often package
                        groups.
                        While similarly named, you should not confuse the
                        <filename>FEATURE_PACKAGES</filename> variable with
                        package groups, which are discussed elsewhere in the
                        documentation.
                    </note>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-FEED_DEPLOYDIR_BASE_URI'><glossterm>FEED_DEPLOYDIR_BASE_URI</glossterm>
            <glossdef>
                <para>
                    Points to the base URL of the server and location within
                    the document-root that provides the metadata and
                    packages required by OPKG to support runtime package
                    management of IPK packages.
                    You set this variable in your
                    <filename>local.conf</filename> file.
                </para>

                <para>
                    Consider the following example:
                    <literallayout class='monospaced'>
     FEED_DEPLOYDIR_BASE_URI = "http://192.168.7.1/BOARD-dir"
                    </literallayout>
                    This example assumes you are serving your packages over
                    HTTP and your databases are located in a directory
                    named <filename>BOARD-dir</filename>, which is underneath
                    your HTTP server's document-root.
                    In this case, the OpenEmbedded build system generates a set
                    of configuration files for you in your target that work
                    with the feed.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-FILES'><glossterm>FILES</glossterm>
            <glossdef>
                <para>
                    The list of directories or files that are placed in packages.
                </para>

                <para>
                    To use the <filename>FILES</filename> variable, provide a
                    package name override that identifies the resulting package.
                    Then, provide a space-separated list of files or paths
                    that identify the files you want included as part of the
                    resulting package.
                    Here is an example:
                    <literallayout class='monospaced'>
     FILES_${PN} += "${bindir}/mydir1/ ${bindir}/mydir2/myfile"
                    </literallayout>
                </para>

                <note>
                    When specifying paths as part of the
                    <filename>FILES</filename> variable, it is good practice
                    to use appropriate path variables.
                    For example, use <filename>${sysconfdir}</filename> rather
                    than <filename>/etc</filename>, or
                    <filename>${bindir}</filename> rather than
                    <filename>/usr/bin</filename>.
                    You can find a list of these variables at the top of the
                    <filename>meta/conf/bitbake.conf</filename> file in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>.
                </note>

                <para>
                    If some of the files you provide with the
                    <filename>FILES</filename> variable are editable and you
                    know they should not be overwritten during the package
                    update process by the Package Management System (PMS), you
                    can identify these files so that the PMS will not
                    overwrite them.
                    See the
                    <link linkend='var-CONFFILES'><filename>CONFFILES</filename></link>
                    variable for information on how to identify these files to
                    the PMS.
                </para>

            </glossdef>
        </glossentry>

        <glossentry id='var-FILESEXTRAPATHS'><glossterm>FILESEXTRAPATHS</glossterm>
            <glossdef>
                <para>
                    Extends the search path the OpenEmbedded build system uses
                    when looking for files and patches as it processes recipes
                    and append files.
                    The default directories BitBake uses when it processes
                    recipes are initially defined by the
                    <link linkend='var-FILESPATH'><filename>FILESPATH</filename></link>
                    variable.
                    You can extend <filename>FILESPATH</filename> variable
                    by using <filename>FILESEXTRAPATHS</filename>.
                </para>

                <para>
                    Best practices dictate that you accomplish this by using
                    <filename>FILESEXTRAPATHS</filename> from within a
                    <filename>.bbappend</filename> file and that you prepend
                    paths as follows:
                    <literallayout class='monospaced'>
     FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
                    </literallayout>
                    In the above example, the build system first looks for files
                    in a directory that has the same name as the corresponding
                    append file.
                    <note>
                        <para>When extending <filename>FILESEXTRAPATHS</filename>,
                        be sure to use the immediate expansion
                        (<filename>:=</filename>) operator.
                        Immediate expansion makes sure that BitBake evaluates
                        <link linkend='var-THISDIR'><filename>THISDIR</filename></link>
                        at the time the directive is encountered rather than at
                        some later time when expansion might result in a
                        directory that does not contain the files you need.
                        </para>
                        <para>Also, include the trailing separating colon
                        character if you are prepending.
                        The trailing colon character is necessary because you
                        are directing BitBake to extend the path by prepending
                        directories to the search path.</para>
                    </note>
                    Here is another common use:
                    <literallayout class='monospaced'>
     FILESEXTRAPATHS_prepend := "${THISDIR}/files:"
                    </literallayout>
                    In this example, the build system extends the
                    <filename>FILESPATH</filename> variable to include a
                    directory named <filename>files</filename> that is in the
                    same directory as the corresponding append file.
                </para>

                <para>
                    Here is a final example that specifically adds three paths:
                    <literallayout class='monospaced'>
     FILESEXTRAPATHS_prepend := "path_1:path_2:path_3:"
                    </literallayout>
                </para>

                <para>
                    By prepending paths in <filename>.bbappend</filename>
                    files, you allow multiple append files that reside in
                    different layers but are used for the same recipe to
                    correctly extend the path.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-FILESOVERRIDES'><glossterm>FILESOVERRIDES</glossterm>
            <glossdef>
                <para>
                    A subset of <link linkend='var-OVERRIDES'><filename>OVERRIDES</filename></link>
                    used by the OpenEmbedded build system for creating
                    <link linkend='var-FILESPATH'><filename>FILESPATH</filename></link>.
                    You can find more information on how overrides are handled
                    in the
                    <ulink url='&YOCTO_DOCS_BB_URL;'>BitBake Manual</ulink>.
                </para>

                <para>
                    By default, the <filename>FILESOVERRIDES</filename>
                    variable is defined as:
                    <literallayout class='monospaced'>
     FILESOVERRIDES = "${TRANSLATED_TARGET_ARCH}:${MACHINEOVERRIDES}:${DISTROOVERRIDES}"
                    </literallayout>

                    <note>
                        Do not hand-edit the <filename>FILESOVERRIDES</filename>
                        variable.
                        The values match up with expected overrides and are
                        used in an expected manner by the build system.
                    </note>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-FILESPATH'><glossterm>FILESPATH</glossterm>
            <glossdef>
                <para>
                    The default set of directories the OpenEmbedded build system
                    uses when searching for patches and files.
                    During the build process, BitBake searches each directory in
                    <filename>FILESPATH</filename> in the specified order when
                    looking for files and patches specified by each
                    <filename>file://</filename> URI in a recipe.
                </para>

                <para>
                    The default value for the <filename>FILESPATH</filename>
                    variable is defined in the <filename>base.bbclass</filename>
                    class found in <filename>meta/classes</filename> in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>:
                    <literallayout class='monospaced'>
     FILESPATH = "${@base_set_filespath(["${FILE_DIRNAME}/${BP}", \
        "${FILE_DIRNAME}/${BPN}", "${FILE_DIRNAME}/files"], d)}"
                    </literallayout>
                    <note>
                        Do not hand-edit the <filename>FILESPATH</filename>
                        variable.
                        If you want the build system to look in directories
                        other than the defaults, extend the
                        <filename>FILESPATH</filename> variable by using the
                        <link linkend='var-FILESEXTRAPATHS'><filename>FILESEXTRAPATHS</filename></link>
                        variable.
                    </note>
                    Be aware that the default <filename>FILESPATH</filename>
                    directories do not map to directories in custom layers
                    where append files (<filename>.bbappend</filename>)
                    are used.
                    If you want the build system to find patches or files
                    that reside with your append files, you need to extend
                    the <filename>FILESPATH</filename> variable by using
                    the
                    <link linkend='var-FILESEXTRAPATHS'><filename>FILESEXTRAPATHS</filename></link>
                    variable.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-FILESYSTEM_PERMS_TABLES'><glossterm>FILESYSTEM_PERMS_TABLES</glossterm>
            <glossdef>
                <para>Allows you to define your own file permissions settings table as part of
                    your configuration for the packaging process.
                    For example, suppose you need a consistent set of custom permissions for
                    a set of groups and users across an entire work project.
                    It is best to do this in the packages themselves but this is not always
                    possible.
                </para>
                <para>
                    By default, the OpenEmbedded build system uses the <filename>fs-perms.txt</filename>, which
                    is located in the <filename>meta/files</filename> folder in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>.
                    If you create your own file permissions setting table, you should place it in your
                    layer or the distro's layer.
                </para>
                <para>
                    You define the <filename>FILESYSTEM_PERMS_TABLES</filename> variable in the
                    <filename>conf/local.conf</filename> file, which is found in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>, to
                    point to your custom <filename>fs-perms.txt</filename>.
                    You can specify more than a single file permissions setting table.
                    The paths you specify to these files must be defined within the
                    <link linkend='var-BBPATH'><filename>BBPATH</filename></link> variable.
                </para>
                <para>
                    For guidance on how to create your own file permissions settings table file,
                    examine the existing <filename>fs-perms.txt</filename>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-FONT_PACKAGES'><glossterm>FONT_PACKAGES</glossterm>
            <glossdef>
                <para>
                    When inheriting the
                    <link linkend='ref-classes-fontcache'><filename>fontcache</filename></link>
                    class, this variable identifies packages containing font
                    files that need to be cached by Fontconfig.
                    By default, the <filename>fontcache</filename> class assumes
                    that fonts are in the recipe's main package
                    (i.e. <filename>${</filename><link linkend='var-PN'><filename>PN</filename></link><filename>}</filename>).
                    Use this variable if fonts you need are in a package
                    other than that main package.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-FULL_OPTIMIZATION'><glossterm>FULL_OPTIMIZATION</glossterm>
            <glossdef>
                <para>
                    The options to pass in
                    <filename><link linkend='var-TARGET_CFLAGS'>TARGET_CFLAGS</link></filename>
                    and <filename><link linkend='var-CFLAGS'>CFLAGS</link></filename>
                    when compiling an optimized system.
                    This variable defaults to
                    "-O2 -pipe ${DEBUG_FLAGS}".
                </para>
            </glossdef>
        </glossentry>
    </glossdiv>

    <glossdiv id='var-glossary-g'><title>G</title>

        <glossentry id='var-GLIBC_GENERATE_LOCALES'><glossterm>GLIBC_GENERATE_LOCALES</glossterm>
            <glossdef>
                <para>
                    Specifies the list of GLIBC locales to generate should you
                    not wish generate all LIBC locals, which can be time
                    consuming.
                    <note>
                        If you specifically remove the locale
                        <filename>en_US.UTF-8</filename>, you must set
                        <link linkend='var-IMAGE_LINGUAS'><filename>IMAGE_LINGUAS</filename></link>
                        appropriately.
                    </note>
                    You can set <filename>GLIBC_GENERATE_LOCALES</filename>
                    in your <filename>local.conf</filename> file.
                    By default, all locales are generated.
                    <literallayout class='monospaced'>
      GLIBC_GENERATE_LOCALES = "en_GB.UTF-8 en_US.UTF-8"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-GROUPADD_PARAM'><glossterm>GROUPADD_PARAM</glossterm>
            <glossdef>
                <para>
                    When inheriting the
                    <link linkend='ref-classes-useradd'><filename>useradd</filename></link>
                    class, this variable
                    specifies for a package what parameters should be passed
                    to the <filename>groupadd</filename> command
                    if you wish to add a group to the system when the package
                    is installed.
                </para>

                <para>
                    Here is an example from the <filename>dbus</filename>
                    recipe:
                    <literallayout class='monospaced'>
     GROUPADD_PARAM_${PN} = "-r netdev"
                    </literallayout>
                    For information on the standard Linux shell command
                    <filename>groupadd</filename>, see
                    <ulink url='http://linux.die.net/man/8/groupadd'></ulink>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-GROUPMEMS_PARAM'><glossterm>GROUPMEMS_PARAM</glossterm>
            <glossdef>
                <para>
                    When inheriting the
                    <link linkend='ref-classes-useradd'><filename>useradd</filename></link>
                    class, this variable
                    specifies for a package what parameters should be passed
                    to the <filename>groupmems</filename> command
                    if you wish to modify the members of a group when the
                    package is installed.
                </para>

                <para>
                    For information on the standard Linux shell command
                    <filename>groupmems</filename>, see
                    <ulink url='http://linux.die.net/man/8/groupmems'></ulink>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-GRUB_GFXSERIAL'><glossterm>GRUB_GFXSERIAL</glossterm>
            <glossdef>
                <para>
                    Configures the GNU GRand Unified Bootloader (GRUB) to have
                    graphics and serial in the boot menu.
                    Set this variable to "1" in your
                    <filename>local.conf</filename> or distribution
                    configuration file to enable graphics and serial
                    in the menu.
                </para>

                <para>
                    See the
                    <link linkend='ref-classes-grub-efi'><filename>grub-efi</filename></link>
                    class for more information on how this variable is used.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-GRUB_OPTS'><glossterm>GRUB_OPTS</glossterm>
            <glossdef>
                <para>
                    Additional options to add to the GNU GRand Unified
                    Bootloader (GRUB) configuration.
                    Use a semi-colon character (<filename>;</filename>) to
                    separate multiple options.
                </para>

                <para>
                    The <filename>GRUB_OPTS</filename> variable is optional.
                    See the
                    <link linkend='ref-classes-grub-efi'><filename>grub-efi</filename></link>
                    class for more information on how this variable is used.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-GRUB_TIMEOUT'><glossterm>GRUB_TIMEOUT</glossterm>
            <glossdef>
                <para>
                    Specifies the timeout before executing the default
                    <filename>LABEL</filename> in the GNU GRand Unified
                    Bootloader (GRUB).
                </para>

                <para>
                    The <filename>GRUB_TIMEOUT</filename> variable is optional.
                    See the
                    <link linkend='ref-classes-grub-efi'><filename>grub-efi</filename></link>
                    class for more information on how this variable is used.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-GTKIMMODULES_PACKAGES'><glossterm>GTKIMMODULES_PACKAGES</glossterm>
            <glossdef>
                <para>
                    When inheriting the
                    <link linkend='ref-classes-gtk-immodules-cache'><filename>gtk-immodules-cache</filename></link>
                    class, this variable specifies the packages that contain the
                    GTK+ input method modules being installed when the modules
                    are in packages other than the main package.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-GUMMIBOOT_CFG'><glossterm>GUMMIBOOT_CFG</glossterm>
            <glossdef>
                <para>
                    When
                    <link linkend='var-EFI_PROVIDER'><filename>EFI_PROVIDER</filename></link>
                    is set to "gummiboot", the
                    <filename>GUMMIBOOT_CFG</filename> variable specifies the
                    configuration file that should be used.
                    By default, the
                    <link linkend='ref-classes-gummiboot'><filename>gummiboot</filename></link>
                    class sets the <filename>GUMMIBOOT_CFG</filename> as
                    follows:
                    <literallayout class='monospaced'>
     GUMMIBOOT_CFG ?= "${<link linkend='var-S'>S</link>}/loader.conf"
                    </literallayout>
                </para>

                <para>
                    For information on Gummiboot, see the
                    <ulink url='http://freedesktop.org/wiki/Software/gummiboot/'>Gummiboot documentation</ulink>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-GUMMIBOOT_ENTRIES'><glossterm>GUMMIBOOT_ENTRIES</glossterm>
            <glossdef>
                <para>
                    When
                    <link linkend='var-EFI_PROVIDER'><filename>EFI_PROVIDER</filename></link>
                    is set to "gummiboot", the
                    <filename>GUMMIBOOT_ENTRIES</filename> variable specifies
                    a list of entry files
                    (<filename>*.conf</filename>) to be installed
                    containing one boot entry per file.
                    By default, the
                    <link linkend='ref-classes-gummiboot'><filename>gummiboot</filename></link>
                    class sets the <filename>GUMMIBOOT_ENTRIES</filename> as
                    follows:
                    <literallayout class='monospaced'>
     GUMMIBOOT_ENTRIES ?= ""
                    </literallayout>
                </para>

                <para>
                    For information on Gummiboot, see the
                    <ulink url='http://freedesktop.org/wiki/Software/gummiboot/'>Gummiboot documentation</ulink>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-GUMMIBOOT_TIMEOUT'><glossterm>GUMMIBOOT_TIMEOUT</glossterm>
            <glossdef>
                <para>
                    When
                    <link linkend='var-EFI_PROVIDER'><filename>EFI_PROVIDER</filename></link>
                    is set to "gummiboot", the
                    <filename>GUMMIBOOT_TIMEOUT</filename> variable specifies
                    the boot menu timeout in seconds.
                    By default, the
                    <link linkend='ref-classes-gummiboot'><filename>gummiboot</filename></link>
                    class sets the <filename>GUMMIBOOT_TIMEOUT</filename> as
                    follows:
                    <literallayout class='monospaced'>
     GUMMIBOOT_TIMEOUT ?= "10"
                    </literallayout>
                </para>

                <para>
                    For information on Gummiboot, see the
                    <ulink url='http://freedesktop.org/wiki/Software/gummiboot/'>Gummiboot documentation</ulink>.
                </para>
            </glossdef>
        </glossentry>

    </glossdiv>

    <glossdiv id='var-glossary-h'><title>H</title>

        <glossentry id='var-HOMEPAGE'><glossterm>HOMEPAGE</glossterm>
            <glossdef>
                <para>Website where more information about the software the recipe is building
                    can be found.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-HOST_CC_ARCH'><glossterm>HOST_CC_ARCH</glossterm>
            <glossdef>
                <para>
                    Specifies architecture-specific compiler flags that are
                    passed to the C compiler.
                </para>

                <para>
                    Default initialization for <filename>HOST_CC_ARCH</filename>
                    varies depending on what is being built:
                    <itemizedlist>
                        <listitem><para>
                            <link linkend='var-TARGET_CC_ARCH'><filename>TARGET_CC_ARCH</filename></link>
                            when building for the target
                            </para></listitem>
                        <listitem><para>
                            <filename>BUILD_CC_ARCH</filename>
                            when building for the build host (i.e.
                            <filename>native</filename>)
                            </para></listitem>
                        <listitem><para>
                            <filename>BUILDSDK_CC_ARCH</filename>
                            when building for an SDK (i.e.
                            <filename>nativesdk</filename>)
                            </para></listitem>
                    </itemizedlist>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-HOST_SYS'><glossterm>HOST_SYS</glossterm>
            <glossdef>
                <para>
                    Specifies the system, including the architecture and the
                    operating system, for with the build is occurring
                    in the context of the current
                    recipe.
                    The OpenEmbedded build system automatically sets this
                    variable.
                    You do not need to set the variable yourself.
                </para>

                <para>
                    Here are two examples:
                    <itemizedlist>
                        <listitem><para>Given a native recipe on a 32-bit
                            x86 machine running Linux, the value is
                            "i686-linux".
                            </para></listitem>
                        <listitem><para>Given a recipe being built for a
                            little-endian MIPS target running Linux,
                            the value might be "mipsel-linux".
                            </para></listitem>
                    </itemizedlist>
                </para>
            </glossdef>
        </glossentry>

    </glossdiv>

    <glossdiv id='var-glossary-i'><title>I</title>

        <glossentry id='var-ICECC_DISABLED'><glossterm>ICECC_DISABLED</glossterm>
            <glossdef>
                <para>
                    Disables or enables the <filename>icecc</filename>
                    (Icecream) function.
                    For more information on this function and best practices
                    for using this variable, see the
                    "<link linkend='ref-classes-icecc'><filename>icecc.bbclass</filename></link>"
                    section.
                </para>

                <para>
                    Setting this variable to "1" in your
                    <filename>local.conf</filename> disables the function:
                    <literallayout class='monospaced'>
     ICECC_DISABLED ??= "1"
                    </literallayout>
                    To enable the function, set the variable as follows:
                    <literallayout class='monospaced'>
     ICECC_DISABLED = ""
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-ICECC_ENV_EXEC'><glossterm>ICECC_ENV_EXEC</glossterm>
            <glossdef>
                <para>
                    Points to the <filename>icecc-create-env</filename> script
                    that you provide.
                    This variable is used by the
                    <link linkend='ref-classes-icecc'><filename>icecc</filename></link>
                    class.
                    You set this variable in your
                    <filename>local.conf</filename> file.
                </para>

                <para>
                    If you do not point to a script that you provide, the
                    OpenEmbedded build system uses the default script provided
                    by the <filename>icecc-create-env.bb</filename> recipe,
                    which is a modified version and not the one that comes with
                    <filename>icecc</filename>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-ICECC_PARALLEL_MAKE'><glossterm>ICECC_PARALLEL_MAKE</glossterm>
            <glossdef>
                <para>
                    Extra options passed to the <filename>make</filename>
                    command during the
                    <link linkend='ref-tasks-compile'><filename>do_compile</filename></link>
                    task that specify parallel compilation.
                    This variable usually takes the form of
                    <filename>-j 4</filename>, where the number
                    represents the maximum number of parallel threads
                    <filename>make</filename> can run.
                    <note>
                        The options passed affect builds on all enabled
                        machines on the network, which are machines running the
                        <filename>iceccd</filename> daemon.
                    </note>
                </para>

                <para>
                    If your enabled machines support multiple cores,
                    coming up with the maximum number of parallel threads
                    that gives you the best performance could take some
                    experimentation since machine speed, network lag,
                    available memory, and existing machine loads can all
                    affect build time.
                    Consequently, unlike the
                    <link linkend='var-PARALLEL_MAKE'><filename>PARALLEL_MAKE</filename></link>
                    variable, there is no rule-of-thumb for setting
                    <filename>ICECC_PARALLEL_MAKE</filename> to achieve
                    optimal performance.
                </para>

                <para>
                    If you do not set <filename>ICECC_PARALLEL_MAKE</filename>,
                    the build system does not use it (i.e. the system does
                    not detect and assign the number of cores as is done with
                    <filename>PARALLEL_MAKE</filename>).
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-ICECC_PATH'><glossterm>ICECC_PATH</glossterm>
            <glossdef>
                <para>
                    The location of the <filename>icecc</filename> binary.
                    You can set this variable in your
                    <filename>local.conf</filename> file.
                    If your <filename>local.conf</filename> file does not define
                    this variable, the
                    <link linkend='ref-classes-icecc'><filename>icecc</filename></link>
                    class attempts to define it by locating
                    <filename>icecc</filename> using <filename>which</filename>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-ICECC_USER_CLASS_BL'><glossterm>ICECC_USER_CLASS_BL</glossterm>
            <glossdef>
                <para>
                    Identifies user classes that you do not want the
                    Icecream distributed compile support to consider.
                    This variable is used by the
                    <link linkend='ref-classes-icecc'><filename>icecc</filename></link>
                    class.
                    You set this variable in your
                    <filename>local.conf</filename> file.
                </para>

                <para>
                    When you list classes using this variable, you are
                    "blacklisting" them from distributed compilation across
                    remote hosts.
                    Any classes you list will be distributed and compiled
                    locally.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-ICECC_USER_PACKAGE_BL'><glossterm>ICECC_USER_PACKAGE_BL</glossterm>
            <glossdef>
                <para>
                    Identifies user recipes that you do not want the
                    Icecream distributed compile support to consider.
                    This variable is used by the
                    <link linkend='ref-classes-icecc'><filename>icecc</filename></link>
                    class.
                    You set this variable in your
                    <filename>local.conf</filename> file.
                </para>

                <para>
                    When you list packages using this variable, you are
                    "blacklisting" them from distributed compilation across
                    remote hosts.
                    Any packages you list will be distributed and compiled
                    locally.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-ICECC_USER_PACKAGE_WL'><glossterm>ICECC_USER_PACKAGE_WL</glossterm>
            <glossdef>
                <para>
                    Identifies user recipes that use an empty
                    <link linkend='var-PARALLEL_MAKE'><filename>PARALLEL_MAKE</filename></link>
                    variable that you want to force remote distributed
                    compilation on using the Icecream distributed compile
                    support.
                    This variable is used by the
                    <link linkend='ref-classes-icecc'><filename>icecc</filename></link>
                    class.
                    You set this variable in your
                    <filename>local.conf</filename> file.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-IMAGE_BASENAME'><glossterm>IMAGE_BASENAME</glossterm>
            <glossdef>
                <para>
                    The base name of image output files.
                    This variable defaults to the recipe name
                    (<filename>${</filename><link linkend='var-PN'><filename>PN</filename></link><filename>}</filename>).
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-IMAGE_BOOT_FILES'><glossterm>IMAGE_BOOT_FILES</glossterm>
            <glossdef>
                <para>
                    A space-separated list of files installed into the
                    boot partition when preparing an image.
                    By default, the files are installed under the same name as
                    the source files.
                    To change the installed name, separate it from the
                    original name with a semi-colon (;).
                    Source files need to be located in
                    <link linkend='var-DEPLOY_DIR_IMAGE'><filename>DEPLOY_DIR_IMAGE</filename></link>.
                    Here are two examples:

                    <literallayout class="monospaced">
     IMAGE_BOOT_FILES = "u-boot.img uImage;kernel"
     IMAGE_BOOT_FILES = "u-boot.${UBOOT_SUFFIX} ${KERNEL_IMAGETYPE}"
                    </literallayout></para>
            </glossdef>
        </glossentry>

        <glossentry id='var-IMAGE_CLASSES'><glossterm>IMAGE_CLASSES</glossterm>
            <glossdef>
                <para>
                    A list of classes that all images should inherit.
                    You typically use this variable to specify the list of
                    classes that register the different types of images
                    the OpenEmbedded build system creates.
                </para>

                <para>
                    The default value for <filename>IMAGE_CLASSES</filename> is
                    <filename>image_types</filename>.
                    You can set this variable in your
                    <filename>local.conf</filename> or in a distribution
                    configuration file.
                </para>

                <para>
                    For more information, see
                    <filename>meta/classes/image_types.bbclass</filename> in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-IMAGE_CMD'><glossterm>IMAGE_CMD</glossterm>
            <glossdef>
                <para>
                    Specifies the command to create the image file for a
                    specific image type, which corresponds to the value set
                    set in
                    <link linkend='var-IMAGE_FSTYPES'><filename>IMAGE_FSTYPES</filename></link>,
                    (e.g. <filename>ext3</filename>,
                    <filename>btrfs</filename>, and so forth).
                    When setting this variable, you should use
                    an override for the associated type.
                    Here is an example:
                    <literallayout class='monospaced'>
     IMAGE_CMD_jffs2 = "mkfs.jffs2 --root=${IMAGE_ROOTFS} \
        --faketime --output=${DEPLOY_DIR_IMAGE}/${IMAGE_NAME}.rootfs.jffs2 \
        ${EXTRA_IMAGECMD}"
                    </literallayout>
                    You typically do not need to set this variable unless
                    you are adding support for a new image type.
                    For more examples on how to set this variable, see the
                    <link linkend='ref-classes-image_types'><filename>image_types</filename></link>
                    class file, which is
                    <filename>meta/classes/image_types.bbclass</filename>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-IMAGE_DEVICE_TABLES'><glossterm>IMAGE_DEVICE_TABLES</glossterm>
            <glossdef>
                <para>
                    Specifies one or more files that contain custom device
                    tables that are passed to the
                    <filename>makedevs</filename> command as part of creating
                    an image.
                    These files list basic device nodes that should be
                    created under <filename>/dev</filename> within the image.
                    If <filename>IMAGE_DEVICE_TABLES</filename> is not set,
                    <filename>files/device_table-minimal.txt</filename> is
                    used, which is located by
                    <link linkend='var-BBPATH'><filename>BBPATH</filename></link>.
                    For details on how you should write device table files,
                    see <filename>meta/files/device_table-minimal.txt</filename>
                    as an example.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-IMAGE_FEATURES'><glossterm>IMAGE_FEATURES</glossterm>
            <glossdef>
                <para>
                    The primary list of features to include in an image.
                    Typically, you configure this variable in an image recipe.
                    Although you can use this variable from your
                    <filename>local.conf</filename> file, which is found in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>,
                    best practices dictate that you do not.
                    <note>
                        To enable extra features from outside the image recipe,
                        use the
                        <filename><link linkend='var-EXTRA_IMAGE_FEATURES'>EXTRA_IMAGE_FEATURES</link></filename> variable.
                    </note>
                    For a list of image features that ships with the Yocto
                    Project, see the
                    "<link linkend="ref-features-image">Image Features</link>"
                    section.
                </para>

                <para>
                    For an example that shows how to customize your image by
                    using this variable, see the
                    "<ulink url='&YOCTO_DOCS_DEV_URL;#usingpoky-extend-customimage-imagefeatures'>Customizing Images Using Custom <filename>IMAGE_FEATURES</filename> and <filename>EXTRA_IMAGE_FEATURES</filename></ulink>"
                    section in the Yocto Project Development Manual.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-IMAGE_FSTYPES'><glossterm>IMAGE_FSTYPES</glossterm>
            <glossdef>
                <para>
                    Specifies the formats the OpenEmbedded build system uses
                    during the build when creating the root filesystem.
                    For example, setting <filename>IMAGE_FSTYPES</filename>
                    as follows causes the build system to create root
                    filesystems using two formats: <filename>.ext3</filename>
                    and <filename>.tar.bz2</filename>:
                    <literallayout class='monospaced'>
     IMAGE_FSTYPES = "ext3 tar.bz2"
                    </literallayout>
                    For the complete list of supported image formats from which
                    you can choose, see
                    <link linkend='var-IMAGE_TYPES'><filename>IMAGE_TYPES</filename></link>.
                </para>

                <note>
                    If you add "live" to <filename>IMAGE_FSTYPES</filename>
                    inside an image recipe, be sure that you do so prior to the
                    "inherit image" line of the recipe or the live image will
                    not build.
                </note>

                <note>
                    Due to the way this variable is processed, it is not
                    possible to update its contents using
                    <filename>_append</filename> or
                    <filename>_prepend</filename>. To add one or more
                    additional options to this variable the
                    <filename>+=</filename> operator must be used.
                </note>
            </glossdef>
        </glossentry>

        <glossentry id='var-IMAGE_INSTALL'><glossterm>IMAGE_INSTALL</glossterm>
            <glossdef>
                <para>
                    Specifies the packages to install into an image.
                    The <filename>IMAGE_INSTALL</filename> variable is a
                    mechanism for an image recipe and you should use it
                    with care to avoid ordering issues.
                    <note>
                        When working with an
                        <link linkend='images-core-image-minimal-initramfs'><filename>core-image-minimal-initramfs</filename></link>
                        image, do not use the <filename>IMAGE_INSTALL</filename>
                        variable to specify packages for installation.
                        Instead, use the
                        <link linkend='var-PACKAGE_INSTALL'><filename>PACKAGE_INSTALL</filename></link>
                        variable, which allows the initial RAM disk (initramfs)
                        recipe to use a fixed set of packages and not be
                        affected by <filename>IMAGE_INSTALL</filename>.
                    </note>
                </para>

                <para>
                    Image recipes set <filename>IMAGE_INSTALL</filename>
                    to specify the packages to install into an image through
                    <filename>image.bbclass</filename>.
                    Additionally, "helper" classes exist, such as
                    <filename>core-image.bbclass</filename>, that can take
                    <filename><link linkend='var-IMAGE_FEATURES'>IMAGE_FEATURES</link></filename>
                    lists and turn these into auto-generated entries in
                    <filename>IMAGE_INSTALL</filename> in addition to its
                    default contents.
                </para>

                <para>
                    Using <filename>IMAGE_INSTALL</filename> with the
                    <filename>+=</filename> operator from the
                    <filename>/conf/local.conf</filename> file or from within
                    an image recipe is not recommended as it can cause ordering
                    issues.
                    Since <filename>core-image.bbclass</filename> sets
                    <filename>IMAGE_INSTALL</filename> to a default value using
                    the <filename>?=</filename> operator, using a
                    <filename>+=</filename> operation against
                    <filename>IMAGE_INSTALL</filename> will result in
                    unexpected behavior when used in
                    <filename>conf/local.conf</filename>.
                    Furthermore, the same operation from within an image
                    recipe may or may not succeed depending on the specific
                    situation.
                    In both these cases, the behavior is contrary to how most
                    users expect the <filename>+=</filename> operator to work.
                </para>

                <para>
                    When you use this variable, it is best to use it as follows:
                    <literallayout class='monospaced'>
     IMAGE_INSTALL_append = " <replaceable>package-name</replaceable>"
                    </literallayout>
                    Be sure to include the space between the quotation character
                    and the start of the package name or names.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-IMAGE_LINGUAS'><glossterm>IMAGE_LINGUAS</glossterm>
            <glossdef>
                <para>
                    Specifies the list of locales to install into the image
                    during the root filesystem construction process.
                    The OpenEmbedded build system automatically splits locale
                    files, which are used for localization, into separate
                    packages.
                    Setting the <filename>IMAGE_LINGUAS</filename> variable
                    ensures that any locale packages that correspond to packages
                    already selected for installation into the image are also
                    installed.
                    Here is an example:
                    <literallayout class='monospaced'>
     IMAGE_LINGUAS = "pt-br de-de"
                    </literallayout>
                    In this example, the build system ensures any Brazilian
                    Portuguese and German locale files that correspond to
                    packages in the image are installed (i.e.
                    <filename>*-locale-pt-br</filename>
                    and <filename>*-locale-de-de</filename> as well as
                    <filename>*-locale-pt</filename>
                    and <filename>*-locale-de</filename>, since some software
                    packages only provide locale files by language and not by
                    country-specific language).
                </para>

                <para>
                    See the
                    <link linkend='var-GLIBC_GENERATE_LOCALES'><filename>GLIBC_GENERATE_LOCALES</filename></link>
                    variable for information on generating GLIBC locales.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-IMAGE_MANIFEST'><glossterm>IMAGE_MANIFEST</glossterm>
            <glossdef>
                <para>
                    The manifest file for the image.
                    This file lists all the installed packages that make up
                    the image.
                    The file contains package information on a line-per-package
                    basis as follows:
                    <literallayout class='monospaced'>
     <replaceable>packagename</replaceable> <replaceable>packagearch</replaceable> <replaceable>version</replaceable>
                    </literallayout>
                </para>

                <para>
                    The
                    <link linkend='ref-classes-image'><filename>image</filename></link>
                    class defines the manifest file as follows:
                    <literallayout class='monospaced'>
     IMAGE_MANIFEST = "${DEPLOY_DIR_IMAGE}/${IMAGE_NAME}.rootfs.manifest"
                    </literallayout>
                    The location is derived using the
                    <link linkend='var-DEPLOY_DIR_IMAGE'><filename>DEPLOY_DIR_IMAGE</filename></link>
                    and
                    <link linkend='var-IMAGE_NAME'><filename>IMAGE_NAME</filename></link>
                    variables.
                    You can find information on how the image
                    is created in the
                    "<link linkend='image-generation-dev-environment'>Image Generation</link>"
                    section.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-IMAGE_NAME'><glossterm>IMAGE_NAME</glossterm>
            <glossdef>
                <para>
                    The name of the output image files minus the extension.
                    This variable is derived using the
                    <link linkend='var-IMAGE_BASENAME'><filename>IMAGE_BASENAME</filename></link>,
                    <link linkend='var-MACHINE'><filename>MACHINE</filename></link>,
                    and
                    <link linkend='var-DATETIME'><filename>DATETIME</filename></link>
                    variables:
                    <literallayout class='monospaced'>
     IMAGE_NAME = "${IMAGE_BASENAME}-${MACHINE}-${DATETIME}"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-IMAGE_OVERHEAD_FACTOR'><glossterm>IMAGE_OVERHEAD_FACTOR</glossterm>
            <glossdef>
                <para>
                    Defines a multiplier that the build system applies to the initial image
                    size for cases when the multiplier times the returned disk usage value
                    for the image is greater than the sum of
                    <filename><link linkend='var-IMAGE_ROOTFS_SIZE'>IMAGE_ROOTFS_SIZE</link></filename>
                    and
                    <filename><link linkend='var-IMAGE_ROOTFS_EXTRA_SPACE'>IMAGE_ROOTFS_EXTRA_SPACE</link></filename>.
                    The result of the multiplier applied to the initial image size creates
                    free disk space in the image as overhead.
                    By default, the build process uses a multiplier of 1.3 for this variable.
                    This default value results in 30% free disk space added to the image when this
                    method is used to determine the final generated image size.
                    You should be aware that post install scripts and the package management
                    system uses disk space inside this overhead area.
                    Consequently, the multiplier does not produce an image with
                    all the theoretical free disk space.
                    See <filename><link linkend='var-IMAGE_ROOTFS_SIZE'>IMAGE_ROOTFS_SIZE</link></filename>
                    for information on how the build system determines the overall image size.
                </para>

                <para>
                    The default 30% free disk space typically gives the image enough room to boot
                    and allows for basic post installs while still leaving a small amount of
                    free disk space.
                    If 30% free space is inadequate, you can increase the default value.
                    For example, the following setting gives you 50% free space added to the image:
                    <literallayout class='monospaced'>
     IMAGE_OVERHEAD_FACTOR = "1.5"
                    </literallayout>
                </para>

                <para>
                    Alternatively, you can ensure a specific amount of free disk space is added
                    to the image by using the
                    <filename><link linkend='var-IMAGE_ROOTFS_EXTRA_SPACE'>IMAGE_ROOTFS_EXTRA_SPACE</link></filename>
                    variable.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-IMAGE_PKGTYPE'><glossterm>IMAGE_PKGTYPE</glossterm>
            <glossdef>
                <para>
                    Defines the package type (DEB, RPM, IPK, or TAR) used
                    by the OpenEmbedded build system.
                    The variable is defined appropriately by the
                    <link linkend='ref-classes-package_deb'><filename>package_deb</filename></link>,
                    <link linkend='ref-classes-package_rpm'><filename>package_rpm</filename></link>,
                    <link linkend='ref-classes-package_ipk'><filename>package_ipk</filename></link>,
                    or
                    <link linkend='ref-classes-package_tar'><filename>package_tar</filename></link>
                    class.
                </para>

                <para>
                    The
                    <link linkend='ref-classes-populate-sdk-*'><filename>package_sdk_base</filename></link>
                    and
                    <link linkend='ref-classes-image'><filename>image</filename></link>
                    classes use the <filename>IMAGE_PKGTYPE</filename> for
                    packaging up images and SDKs.
                </para>

                <para>
                    You should not set the <filename>IMAGE_PKGTYPE</filename>
                    manually.
                    Rather, the variable is set indirectly through the
                    appropriate
                    <link linkend='ref-classes-package'><filename>package_*</filename></link>
                    class using the
                    <link linkend='var-PACKAGE_CLASSES'><filename>PACKAGE_CLASSES</filename></link>
                    variable.
                    The OpenEmbedded build system uses the first package type
                    (e.g. DEB, RPM, or IPK) that appears with the variable
                    <note>
                        Files using the <filename>.tar</filename> format are
                        never used as a substitute packaging format for DEB,
                        RPM, and IPK formatted files for your image or SDK.
                    </note>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-IMAGE_POSTPROCESS_COMMAND'><glossterm>IMAGE_POSTPROCESS_COMMAND</glossterm>
            <glossdef>
                <para>
                    Added by classes to run post processing commands once the
                    OpenEmbedded build system has created the image.
                    You can specify shell commands separated by semicolons:
                    <literallayout class='monospaced'>
     IMAGE_POSTPROCESS_COMMAND += "<replaceable>shell_command</replaceable>; ... "
                    </literallayout>
                    If you need to pass the path to the root filesystem within
                    the command, you can use
                    <filename>${IMAGE_ROOTFS}</filename>, which points to
                    the root filesystem image.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-IMAGE_ROOTFS'><glossterm>IMAGE_ROOTFS</glossterm>
            <glossdef>
                <para>
                    The location of the root filesystem while it is under
                    construction (i.e. during the
                    <link linkend='ref-tasks-rootfs'><filename>do_rootfs</filename></link>
                    task).
                    This variable is not configurable.
                    Do not change it.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-IMAGE_ROOTFS_ALIGNMENT'><glossterm>IMAGE_ROOTFS_ALIGNMENT</glossterm>
            <glossdef>
                <para>
                    Specifies the alignment for the output image file in
                    Kbytes.
                    If the size of the image is not a multiple of
                    this value, then the size is rounded up to the nearest
                    multiple of the value.
                    The default value is "1".
                    See
                    <link linkend='var-IMAGE_ROOTFS_SIZE'><filename>IMAGE_ROOTFS_SIZE</filename></link>
                    for additional information.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-IMAGE_ROOTFS_EXTRA_SPACE'><glossterm>IMAGE_ROOTFS_EXTRA_SPACE</glossterm>
            <glossdef>
                <para>
                    Defines additional free disk space created in the image in Kbytes.
                    By default, this variable is set to "0".
                    This free disk space is added to the image after the build system determines
                    the image size as described in
                    <filename><link linkend='var-IMAGE_ROOTFS_SIZE'>IMAGE_ROOTFS_SIZE</link></filename>.
                </para>

                <para>
                    This variable is particularly useful when you want to ensure that a
                    specific amount of free disk space is available on a device after an image
                    is installed and running.
                    For example, to be sure 5 Gbytes of free disk space is available, set the
                    variable as follows:
                    <literallayout class='monospaced'>
     IMAGE_ROOTFS_EXTRA_SPACE = "5242880"
                    </literallayout>
                </para>

                <para>
                    For example, the Yocto Project Build Appliance specifically requests 40 Gbytes
                    of extra space with the line:
                    <literallayout class='monospaced'>
     IMAGE_ROOTFS_EXTRA_SPACE = "41943040"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-IMAGE_ROOTFS_SIZE'><glossterm>IMAGE_ROOTFS_SIZE</glossterm>
            <glossdef>
                <para>
                    Defines the size in Kbytes for the generated image.
                    The OpenEmbedded build system determines the final size for the generated
                    image using an algorithm that takes into account the initial disk space used
                    for the generated image, a requested size for the image, and requested
                    additional free disk space to be added to the image.
                    Programatically, the build system determines the final size of the
                    generated image as follows:
                    <literallayout class='monospaced'>
    if (image-du * overhead) &lt; rootfs-size:
	internal-rootfs-size = rootfs-size + xspace
    else:
	internal-rootfs-size = (image-du * overhead) + xspace

    where:

      image-du = Returned value of the du command on
                 the image.

      overhead = IMAGE_OVERHEAD_FACTOR

      rootfs-size = IMAGE_ROOTFS_SIZE

      internal-rootfs-size = Initial root filesystem
                             size before any modifications.

      xspace = IMAGE_ROOTFS_EXTRA_SPACE
                    </literallayout>
                    See the <link linkend='var-IMAGE_OVERHEAD_FACTOR'><filename>IMAGE_OVERHEAD_FACTOR</filename></link>
                    and <link linkend='var-IMAGE_ROOTFS_EXTRA_SPACE'><filename>IMAGE_ROOTFS_EXTRA_SPACE</filename></link>
                    variables for related information.
<!--                    In the above example, <filename>overhead</filename> is defined by the
                    <filename><link linkend='var-IMAGE_OVERHEAD_FACTOR'>IMAGE_OVERHEAD_FACTOR</link></filename>
                    variable, <filename>xspace</filename> is defined by the
                    <filename><link linkend='var-IMAGE_ROOTFS_EXTRA_SPACE'>IMAGE_ROOTFS_EXTRA_SPACE</link></filename>
                    variable, and <filename>du</filename> is the results of the disk usage command
                    on the initially generated image. -->
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-IMAGE_TYPEDEP'><glossterm>IMAGE_TYPEDEP</glossterm>
            <glossdef>
                <para>
                    Specifies a dependency from one image type on another.
                    Here is an example from the
                    <link linkend='ref-classes-image-live'><filename>image-live</filename></link>
                    class:
                    <literallayout class='monospaced'>
     IMAGE_TYPEDEP_live = "ext3"
                    </literallayout>
                    In the previous example, the variable ensures that when
                    "live" is listed with the
                    <link linkend='var-IMAGE_FSTYPES'><filename>IMAGE_FSTYPES</filename></link>
                    variable, the OpenEmbedded build system produces an
                    <filename>ext3</filename> image first since one of the
                    components of the live
                    image is an <filename>ext3</filename>
                    formatted partition containing the root
                    filesystem.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-IMAGE_TYPES'><glossterm>IMAGE_TYPES</glossterm>
            <glossdef>
                <para>
                    Specifies the complete list of supported image types
                    by default:
                    <literallayout class='monospaced'>
     jffs2
     jffs2.sum
     cramfs
     ext2
     ext2.gz
     ext2.bz2
     ext3
     ext3.gz
     ext2.lzma
     btrfs
     live
     squashfs
     squashfs-xz
     ubi
     ubifs
     tar
     tar.gz
     tar.bz2
     tar.xz
     cpio
     cpio.gz
     cpio.xz
     cpio.lzma
     vmdk
     elf
                    </literallayout>
                    For more information about these types of images, see
                    <filename>meta/classes/image_types*.bbclass</filename>
                    in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-INC_PR'><glossterm>INC_PR</glossterm>
            <glossdef>
                <para>Helps define the recipe revision for recipes that share
                    a common <filename>include</filename> file.
                    You can think of this variable as part of the recipe revision
                    as set from within an include file.</para>
                <para>Suppose, for example, you have a set of recipes that
                    are used across several projects.
                    And, within each of those recipes the revision
                    (its <link linkend='var-PR'><filename>PR</filename></link>
                    value) is set accordingly.
                    In this case, when the revision of those recipes changes,
                    the burden is on you to find all those recipes and
                    be sure that they get changed to reflect the updated
                    version of the recipe.
                    In this scenario, it can get complicated when recipes
                    that are used in many places and provide common functionality
                    are upgraded to a new revision.</para>
                <para>A more efficient way of dealing with this situation is
                    to set the <filename>INC_PR</filename> variable inside
                    the <filename>include</filename> files that the recipes
                    share and then expand the <filename>INC_PR</filename>
                    variable within the recipes to help
                    define the recipe revision.
                    </para>
                <para>
                    The following provides an example that shows how to use
                    the <filename>INC_PR</filename> variable
                    given a common <filename>include</filename> file that
                    defines the variable.
                    Once the variable is defined in the
                    <filename>include</filename> file, you can use the
                    variable to set the <filename>PR</filename> values in
                    each recipe.
                    You will notice that when you set a recipe's
                    <filename>PR</filename> you can provide more granular
                    revisioning by appending values to the
                    <filename>INC_PR</filename> variable:
                    <literallayout class='monospaced'>
recipes-graphics/xorg-font/xorg-font-common.inc:INC_PR = "r2"
recipes-graphics/xorg-font/encodings_1.0.4.bb:PR = "${INC_PR}.1"
recipes-graphics/xorg-font/font-util_1.3.0.bb:PR = "${INC_PR}.0"
recipes-graphics/xorg-font/font-alias_1.0.3.bb:PR = "${INC_PR}.3"
                    </literallayout>
                    The first line of the example establishes the baseline
                    revision to be used for all recipes that use the
                    <filename>include</filename> file.
                    The remaining lines in the example are from individual
                    recipes and show how the <filename>PR</filename> value
                    is set.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-INCOMPATIBLE_LICENSE'><glossterm>INCOMPATIBLE_LICENSE</glossterm>
            <glossdef>
                <para>
                    Specifies a space-separated list of license names
                    (as they would appear in
                    <link linkend='var-LICENSE'><filename>LICENSE</filename></link>)
                    that should be excluded from the build.
                    Recipes that provide no alternatives to listed incompatible
                    licenses are not built.
                    Packages that are individually licensed with the specified
                    incompatible licenses will be deleted.
                </para>

                <note>
                    This functionality is only regularly tested using
                    the following setting:
                    <literallayout class='monospaced'>
     INCOMPATIBLE_LICENSE = "GPL-3.0 LGPL-3.0 AGPL-3.0"
                    </literallayout>
                    Although you can use other settings, you might be required
                    to remove dependencies on or provide alternatives to
                    components that are required to produce a functional system
                    image.
                </note>
            </glossdef>
        </glossentry>

        <glossentry id='var-INHIBIT_DEFAULT_DEPS'><glossterm>INHIBIT_DEFAULT_DEPS</glossterm>
            <glossdef>
                <para>
                    Prevents the default dependencies, namely the C compiler
                    and standard C library (libc), from being added to
                    <link linkend='var-DEPENDS'><filename>DEPENDS</filename></link>.
                    This variable is usually used within recipes that do not
                    require any compilation using the C compiler.
                </para>

                <para>
                    Set the variable to "1" to prevent the default dependencies
                    from being added.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-INHIBIT_PACKAGE_DEBUG_SPLIT'><glossterm>INHIBIT_PACKAGE_DEBUG_SPLIT</glossterm>
            <glossdef>

                <para>
                    Prevents the OpenEmbedded build system from splitting
                    out debug information during packaging.
                    By default, the build system splits out debugging
                    information during the
                    <link linkend='ref-tasks-package'><filename>do_package</filename></link>
                    task.
                    For more information on how debug information is split out,
                    see the
                    <link linkend='var-PACKAGE_DEBUG_SPLIT_STYLE'><filename>PACKAGE_DEBUG_SPLIT_STYLE</filename></link>
                    variable.
                </para>

                <para>
                    To prevent the build system from splitting out
                    debug information during packaging, set the
                    <filename>INHIBIT_PACKAGE_DEBUG_SPLIT</filename> variable
                    as follows:
                    <literallayout class='monospaced'>
     INHIBIT_PACKAGE_DEBUG_SPLIT = "1"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-INHIBIT_PACKAGE_STRIP'><glossterm>INHIBIT_PACKAGE_STRIP</glossterm>
            <glossdef>
                <para>
                    If set to "1", causes the build to not strip binaries in resulting packages.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-INHERIT'><glossterm>INHERIT</glossterm>
            <glossdef>
                <para>
                    Causes the named class to be inherited at
                    this point during parsing.
                    The variable is only valid in configuration files.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-INHERIT_DISTRO'><glossterm>INHERIT_DISTRO</glossterm>
            <glossdef>
                <para>
                    Lists classes that will be inherited at the
                    distribution level.
                    It is unlikely that you want to edit this variable.
                </para>

                <para>
                    The default value of the variable is set as follows in the
                    <filename>meta/conf/distro/defaultsetup.conf</filename>
                    file:
                    <literallayout class='monospaced'>
     INHERIT_DISTRO ?= "debian devshell sstate license"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-INITRAMFS_FSTYPES'><glossterm>INITRAMFS_FSTYPES</glossterm>
            <glossdef>
                <para>
                    Defines the format for the output image of an initial
                    RAM disk (initramfs), which is used during boot.
                    Supported formats are the same as those supported by the
                    <link linkend='var-IMAGE_FSTYPES'><filename>IMAGE_FSTYPES</filename></link>
                    variable.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-INITRAMFS_IMAGE'><glossterm>INITRAMFS_IMAGE</glossterm>
            <glossdef>
                <para>
                    Causes the OpenEmbedded build system to build an additional
                    recipe as a dependency to your root filesystem recipe
                    (e.g. <filename>core-image-sato</filename>).
                    The additional recipe is used to create an initial RAM disk
                    (initramfs) that might be needed during the initial boot of
                    the target system to accomplish such things as loading
                    kernel modules prior to mounting the root file system.
                </para>

                <para>
                    When you set the variable, specify the name of the
                    initramfs you want created.
                    The following example, which is set in the
                    <filename>local.conf</filename> configuration file, causes
                    a separate recipe to be created that results in an
                    initramfs image named
                    <filename>core-image-sato-initramfs.bb</filename> to be
                    created:
                    <literallayout class='monospaced'>
     INITRAMFS_IMAGE = "core-image-minimal-initramfs"
                    </literallayout>
                    By default, the
                    <link linkend='ref-classes-kernel'><filename>kernel</filename></link>
                    class sets this variable to a null string as follows:
                    <literallayout class='monospaced'>
     INITRAMFS_IMAGE = ""
                    </literallayout>
                </para>

                <para>
                    See the
                    <ulink url='&YOCTO_GIT_URL;/cgit/cgit.cgi/poky/tree/meta-yocto/conf/local.conf.sample.extended'><filename>local.conf.sample.extended</filename></ulink>
                    file for additional information.
                    You can also reference the
                    <ulink url='&YOCTO_GIT_URL;/cgit/cgit.cgi/poky/tree/meta/classes/kernel.bbclass'><filename>kernel.bbclass</filename></ulink>
                    file to see how the variable is used.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-INITRAMFS_IMAGE_BUNDLE'><glossterm>INITRAMFS_IMAGE_BUNDLE</glossterm>
            <glossdef>
                <para>
                    Controls whether or not the image recipe specified by
                    <link linkend='var-INITRAMFS_IMAGE'><filename>INITRAMFS_IMAGE</filename></link>
                    is run through an extra pass during kernel compilation
                    in order to build a single binary that contains both the
                    kernel image and the initial RAM disk (initramfs).
                    Using an extra compilation pass ensures that when a kernel
                    attempts to use an initramfs, it does not encounter
                    circular dependencies should the initramfs include kernel
                    modules.
                </para>

                <para>
                    The combined binary is deposited into the
                    <filename>tmp/deploy</filename> directory, which is part
                    of the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
                </para>

                <para>
                    Setting the variable to "1" in a configuration file causes
                    the OpenEmbedded build system to make the extra pass during
                    kernel compilation:
                    <literallayout class='monospaced'>
     INITRAMFS_IMAGE_BUNDLE = "1"
                    </literallayout>
                    By default, the
                    <link linkend='ref-classes-kernel'><filename>kernel</filename></link>
                    class sets this variable to a null string as follows:
                    <literallayout class='monospaced'>
     INITRAMFS_IMAGE_BUNDLE = ""
                    </literallayout>
                    <note>
                        You must set the
                        <filename>INITRAMFS_IMAGE_BUNDLE</filename> variable in
                        a configuration file.
                        You cannot set the variable in a recipe file.
                    </note>
                    See the
                    <ulink url='&YOCTO_GIT_URL;/cgit/cgit.cgi/poky/tree/meta-yocto/conf/local.conf.sample.extended'><filename>local.conf.sample.extended</filename></ulink>
                    file for additional information.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-INITRD'><glossterm>INITRD</glossterm>
            <glossdef>
                <para>
                    Indicates list of filesystem images to concatenate and use
                    as an initial RAM disk (<filename>initrd</filename>).
                </para>

                <para>
                    The <filename>INITRD</filename> variable is an optional
                    variable used with the
                    <link linkend='ref-classes-bootimg'><filename>bootimg</filename></link>
                    class.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-INITRD_IMAGE'><glossterm>INITRD_IMAGE</glossterm>
            <glossdef>
                <para>
                    When building a "live" bootable image (i.e. when
                    <link linkend='var-IMAGE_FSTYPES'><filename>IMAGE_FSTYPES</filename></link>
                    contains "live"), <filename>INITRD_IMAGE</filename>
                    specifies the image recipe that should be built
                    to provide the initial RAM disk image.
                    The default value is "core-image-minimal-initramfs".
                </para>

                <para>
                    See the
                    <link linkend='ref-classes-image-live'><filename>image-live</filename></link>
                    class for more information.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-INITSCRIPT_NAME'><glossterm>INITSCRIPT_NAME</glossterm>
            <glossdef>
                <para>
                    The filename of the initialization script as installed to
                    <filename>${sysconfdir}/init.d</filename>.
                </para>
                <para>
                    This variable is used in recipes when using <filename>update-rc.d.bbclass</filename>.
                    The variable is mandatory.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-INITSCRIPT_PACKAGES'><glossterm>INITSCRIPT_PACKAGES</glossterm>
            <glossdef>
                <para>
                    A list of the packages that contain initscripts.
                    If multiple packages are specified, you need to append the package name
                    to the other <filename>INITSCRIPT_*</filename> as an override.</para>
                 <para>
                    This variable is used in recipes when using <filename>update-rc.d.bbclass</filename>.
                    The variable is optional and defaults to the
                    <link linkend='var-PN'><filename>PN</filename></link> variable.
                </para>
           </glossdef>
        </glossentry>

        <glossentry id='var-INITSCRIPT_PARAMS'><glossterm>INITSCRIPT_PARAMS</glossterm>
            <glossdef>
                <para>
                    Specifies the options to pass to <filename>update-rc.d</filename>.
                    Here is an example:
                    <literallayout class='monospaced'>
     INITSCRIPT_PARAMS = "start 99 5 2 . stop 20 0 1 6 ."
                    </literallayout>
                    In this example, the script has a runlevel of 99,
                    starts the script in initlevels 2 and 5, and
                    stops the script in levels 0, 1 and 6.
                </para>
                <para>
                    The variable's default value is "defaults", which is
                    set in the
                    <link linkend='ref-classes-update-rc.d'><filename>update-rc.d</filename></link>
                    class.
                </para>
                <para>
                    The value in
                    <filename>INITSCRIPT_PARAMS</filename> is passed through
                    to the <filename>update-rc.d</filename> command.
                    For more information on valid parameters, please see the
                    <filename>update-rc.d</filename> manual page at
                    <ulink url='http://www.tin.org/bin/man.cgi?section=8&amp;topic=update-rc.d'></ulink>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-INSANE_SKIP'><glossterm>INSANE_SKIP</glossterm>
            <glossdef>
                <para>
                    Specifies the QA checks to skip for a specific package
                    within a recipe.
                    For example, to skip the check for symbolic link
                    <filename>.so</filename> files in the main package of a
                    recipe, add the following to the recipe.
                    The package name override must be used, which in this
                    example is <filename>${PN}</filename>:
                    <literallayout class='monospaced'>
     INSANE_SKIP_${PN} += "dev-so"
                    </literallayout>
                </para>
                <para>
                    See the "<link linkend='ref-classes-insane'><filename>insane.bbclass</filename></link>"
                    section for a list of the valid QA checks you can
                    specify using this variable.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-IPK_FEED_URIS'><glossterm>IPK_FEED_URIS</glossterm>
            <glossdef>
                <para>
                    When the IPK backend is in use and package management
                    is enabled on the target, you can use this variable to
                    set up <filename>opkg</filename> in the target image
                    to point to package feeds on a nominated server.
                    Once the feed is established, you can perform
                    installations or upgrades using the package manager
                    at runtime.
                </para>
            </glossdef>
        </glossentry>

<!--
        <glossentry id='var-INTERCEPT_DIR'><glossterm>INTERCEPT_DIR</glossterm>
            <glossdef>
                <para>
                    An environment variable that defines the directory where
                    post installation hooks are installed for the
                    post install environment.
                    This variable is fixed as follows:
                    <literallayout class='monospaced'>
     ${WORKDIR}/intercept_scripts
                    </literallayout>
                </para>

                <para>
                    After installation of a target's root filesystem,
                    post installation scripts, which are essentially bash scripts,
                    are all executed just a single time.
                    Limiting execution of these scripts minimizes installation
                    time that would be lengthened due to  certain packages
                    triggering redundant operations.
                    For example, consider the installation of font packages
                    as a common example.
                    Without limiting the execution of post installation scripts,
                    all font directories would be rescanned to create the
                    cache after each individual font package was installed.
                </para>

                <para>
                    Do not edit the <filename>INTERCEPT_DIR</filename>
                    variable.
                </para>
            </glossdef>
        </glossentry>
-->

    </glossdiv>

<!--            <glossdiv id='var-glossary-j'><title>J</title>-->
<!--            </glossdiv>-->

   <glossdiv id='var-glossary-k'><title>K</title>

        <glossentry id='var-KARCH'><glossterm>KARCH</glossterm>
            <glossdef>
                <para>
                    Defines the kernel architecture used when assembling
                    the configuration.
                    Architectures supported for this release are:
                    <literallayout class='monospaced'>
     powerpc
     i386
     x86_64
     arm
     qemu
     mips
                    </literallayout>
                </para>

                <para>
                    You define the <filename>KARCH</filename> variable in the
                    <ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;#bsp-descriptions'>BSP Descriptions</ulink>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-KBRANCH'><glossterm>KBRANCH</glossterm>
            <glossdef>
                <para>
                    A regular expression used by the build process to explicitly
                    identify the kernel branch that is validated, patched
                    and configured during a build.
                    The <filename>KBRANCH</filename> variable is optional.
                    You can use it to trigger checks to ensure the exact kernel
                    branch you want is being used by the build process.
                </para>

                <para>
                    Values for this variable are set in the kernel's recipe
                    file and the kernel's append file.
                    For example, if you are using the Yocto Project kernel that
                    is based on the Linux 3.10 kernel, the kernel recipe file
                    is the
                    <filename>meta/recipes-kernel/linux/linux-yocto_3.10.bb</filename>
                    file.
                    Following is the default value for <filename>KBRANCH</filename>
                    and the default override for the architectures the Yocto
                    Project supports:
                    <literallayout class='monospaced'>
     KBRANCH_DEFAULT = "standard/base"
     KBRANCH = "${KBRANCH_DEFAULT}"
                    </literallayout>
                    This branch exists in the <filename>linux-yocto-3.10</filename>
                    kernel Git repository
                    <ulink url='&YOCTO_GIT_URL;/cgit.cgi/linux-yocto-3.10/refs/heads'></ulink>.
                </para>

                <para>
                    This variable is also used from the kernel's append file
                    to identify the kernel branch specific to a particular
                    machine or target hardware.
                    The kernel's append file is located in the BSP layer for
                    a given machine.
                    For example, the kernel append file for the Crown Bay BSP is in the
                    <filename>meta-intel</filename> Git repository and is named
                    <filename>meta-crownbay/recipes-kernel/linux/linux-yocto_3.10.bbappend</filename>.
                    Here are the related statements from the append file:
                    <literallayout class='monospaced'>
     COMPATIBLE_MACHINE_crownbay = "crownbay"
     KMACHINE_crownbay = "crownbay"
     KBRANCH_crownbay = "standard/crownbay"
     KERNEL_FEATURES_append_crownbay = " features/drm-emgd/drm-emgd-1.18 cfg/vesafb"

     COMPATIBLE_MACHINE_crownbay-noemgd = "crownbay-noemgd"
     KMACHINE_crownbay-noemgd = "crownbay"
     KBRANCH_crownbay-noemgd = "standard/crownbay"
     KERNEL_FEATURES_append_crownbay-noemgd = " cfg/vesafb"
                    </literallayout>
                        The <filename>KBRANCH_*</filename> statements identify
                        the kernel branch to use when building for the Crown
                        Bay BSP.
                        In this case there are two identical statements: one
                        for each type of Crown Bay machine.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-KBRANCH_DEFAULT'><glossterm>KBRANCH_DEFAULT</glossterm>
            <glossdef>
                <para>
                    Defines the Linux kernel source repository's default
                    branch used to build the Linux kernel.
                    The <filename>KBRANCH_DEFAULT</filename> value is
                    the default value for
                    <link linkend='var-KBRANCH'><filename>KBRANCH</filename></link>.
                    Unless you specify otherwise,
                    <filename>KBRANCH_DEFAULT</filename> initializes to
                    "master".
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-KERNEL_EXTRA_ARGS'><glossterm>KERNEL_EXTRA_ARGS</glossterm>
            <glossdef>
                <para>
                    Specifies additional <filename>make</filename>
                    command-line arguments the OpenEmbedded build system
                    passes on when compiling the kernel.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-KERNEL_FEATURES'><glossterm>KERNEL_FEATURES</glossterm>
            <glossdef>
                <para>Includes additional metadata from the Yocto Project kernel Git repository.
                    In the OpenEmbedded build system, the default Board Support Packages (BSPs)
                    <ulink url='&YOCTO_DOCS_DEV_URL;#metadata'>Metadata</ulink>
                    is provided through
                    the <link linkend='var-KMACHINE'><filename>KMACHINE</filename></link>
                    and <link linkend='var-KBRANCH'><filename>KBRANCH</filename></link> variables.
                    You can use the <filename>KERNEL_FEATURES</filename> variable to further
                    add metadata for all BSPs.</para>
                <para>The metadata you add through this variable includes config fragments and
                    features descriptions,
                    which usually includes patches as well as config fragments.
                    You typically override the <filename>KERNEL_FEATURES</filename> variable
                    for a specific machine.
                    In this way, you can provide validated, but optional, sets of kernel
                    configurations and features.</para>
                <para>For example, the following adds <filename>netfilter</filename> to all
                    the Yocto Project kernels and adds sound support to the <filename>qemux86</filename>
                    machine:
                    <literallayout class='monospaced'>
     # Add netfilter to all linux-yocto kernels
     KERNEL_FEATURES="features/netfilter"

     # Add sound support to the qemux86 machine
     KERNEL_FEATURES_append_qemux86=" cfg/sound"
                    </literallayout></para>
            </glossdef>
        </glossentry>

        <glossentry id='var-KERNEL_IMAGE_BASE_NAME'><glossterm>KERNEL_IMAGE_BASE_NAME</glossterm>
            <glossdef>
                <para>
                    The base name of the kernel image.
                    This variable is set in the
                    <link linkend='ref-classes-kernel'>kernel</link> class
                    as follows:
                    <literallayout class='monospaced'>
     KERNEL_IMAGE_BASE_NAME ?= "${KERNEL_IMAGETYPE}-${PKGE}-${PKGV}-${PKGR}-${MACHINE}-${DATETIME}"
                    </literallayout>
                    See the
                    <link linkend='var-KERNEL_IMAGETYPE'><filename>KERNEL_IMAGETYPE</filename></link>,
                    <link linkend='var-PKGE'><filename>PKGE</filename></link>,
                    <link linkend='var-PKGV'><filename>PKGV</filename></link>,
                    <link linkend='var-PKGR'><filename>PKGR</filename></link>,
                    <link linkend='var-MACHINE'><filename>MACHINE</filename></link>,
                    and
                    <link linkend='var-DATETIME'><filename>DATETIME</filename></link>
                    variables for additional information.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-KERNEL_IMAGETYPE'><glossterm>KERNEL_IMAGETYPE</glossterm>
            <glossdef>
                <para>The type of kernel to build for a device, usually set by the
                    machine configuration files and defaults to "zImage".
                    This variable is used
                    when building the kernel and is passed to <filename>make</filename> as the target to
                    build.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-KERNEL_MODULE_AUTOLOAD'><glossterm>KERNEL_MODULE_AUTOLOAD</glossterm>
            <glossdef>
                <para>
                    Lists kernel modules that need to be auto-loaded during
                    boot.
                    <note>
                        This variable replaces the deprecated
                        <link linkend='var-module_autoload'><filename>module_autoload</filename></link>
                        variable.
                    </note>
                </para>

                <para>
                    You can use the <filename>KERNEL_MODULE_AUTOLOAD</filename>
                    variable anywhere that it can be
                    recognized by the kernel recipe or by an out-of-tree kernel
                    module recipe (e.g. a machine configuration file, a
                    distribution configuration file, an append file for the
                    recipe, or the recipe itself).
                </para>

                <para>
                    Specify it as follows:
                    <literallayout class='monospaced'>
     KERNEL_MODULE_AUTOLOAD += "<replaceable>module_name1</replaceable> <replaceable>module_name2</replaceable> <replaceable>module_name3</replaceable>"
                    </literallayout>
                </para>

                <para>
                    Including <filename>KERNEL_MODULE_AUTOLOAD</filename> causes
                    the OpenEmbedded build system to populate the
                    <filename>/etc/modules-load.d/modname.conf</filename>
                    file with the list of modules to be auto-loaded on boot.
                    The modules appear one-per-line in the file.
                    Here is an example of the most common use case:
                    <literallayout class='monospaced'>
     KERNEL_MODULE_AUTOLOAD += "<replaceable>module_name</replaceable>"
                    </literallayout>
                </para>

                <para>
                    For information on how to populate the
                    <filename>modname.conf</filename> file with
                    <filename>modprobe.d</filename> syntax lines, see the
                    <link linkend='var-KERNEL_MODULE_PROBECONF'><filename>KERNEL_MODULE_PROBECONF</filename></link>
                    variable.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-KERNEL_MODULE_PROBECONF'><glossterm>KERNEL_MODULE_PROBECONF</glossterm>
            <glossdef>
                <para>
                    Provides a list of modules for which the OpenEmbedded
                    build system expects to find
                    <filename>module_conf_</filename><replaceable>modname</replaceable>
                    values that specify configuration for each of the modules.
                    For information on how to provide those module
                    configurations, see the
                    <link linkend='var-module_conf'><filename>module_conf_*</filename></link>
                    variable.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-KERNEL_PATH'><glossterm>KERNEL_PATH</glossterm>
            <glossdef>
                <para>
                    The location of the kernel sources.
                    This variable is set to the value of the
                    <link linkend='var-STAGING_KERNEL_DIR'><filename>STAGING_KERNEL_DIR</filename></link>
                    within the
                    <link linkend='ref-classes-module'><filename>module</filename></link>
                    class.
                    For information on how this variable is used, see the
                    "<ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;#incorporating-out-of-tree-modules'>Incorporating Out-of-Tree Modules</ulink>"
                    section.
                </para>

                <para>
                    To help maximize compatibility with out-of-tree drivers
                    used to build modules, the OpenEmbedded build system also
                    recognizes and uses the
                    <link linkend='var-KERNEL_SRC'><filename>KERNEL_SRC</filename></link>
                    variable, which is identical to the
                    <filename>KERNEL_PATH</filename> variable.
                    Both variables are common variables used by external
                    Makefiles to point to the kernel source directory.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-KERNEL_SRC'><glossterm>KERNEL_SRC</glossterm>
            <glossdef>
                <para>
                    The location of the kernel sources.
                    This variable is set to the value of the
                    <link linkend='var-STAGING_KERNEL_DIR'><filename>STAGING_KERNEL_DIR</filename></link>
                    within the
                    <link linkend='ref-classes-module'><filename>module</filename></link>
                    class.
                    For information on how this variable is used, see the
                    "<ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;#incorporating-out-of-tree-modules'>Incorporating Out-of-Tree Modules</ulink>"
                    section.
                </para>

                <para>
                    To help maximize compatibility with out-of-tree drivers
                    used to build modules, the OpenEmbedded build system also
                    recognizes and uses the
                    <link linkend='var-KERNEL_PATH'><filename>KERNEL_PATH</filename></link>
                    variable, which is identical to the
                    <filename>KERNEL_SRC</filename> variable.
                    Both variables are common variables used by external
                    Makefiles to point to the kernel source directory.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-KFEATURE_DESCRIPTION'><glossterm>KFEATURE_DESCRIPTION</glossterm>
            <glossdef>
                <para>
                    Provides a short description of a configuration fragment.
                    You use this variable in the <filename>.scc</filename>
                    file that describes a configuration fragment file.
                    Here is the variable used in a file named
                    <filename>smp.scc</filename> to describe SMP being
                    enabled:
                    <literallayout class='monospaced'>
     define KFEATURE_DESCRIPTION "Enable SMP"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-KMACHINE'><glossterm>KMACHINE</glossterm>
            <glossdef>
                <para>
                    The machine as known by the kernel.
                    Sometimes the machine name used by the kernel does not match the machine name
                    used by the OpenEmbedded build system.
                    For example, the machine name that the OpenEmbedded build system understands as
                    <filename>qemuarm</filename> goes by a different name in the Linux Yocto kernel.
                    The kernel understands that machine as <filename>arm_versatile926ejs</filename>.
                    For cases like these, the <filename>KMACHINE</filename> variable maps the
                    kernel machine name to the OpenEmbedded build system machine name.
                </para>

                <para>
                    Kernel machine names are initially defined in the
                    Yocto Linux Kernel's <filename>meta</filename> branch.
                    From the <filename>meta</filename> branch, look in
                    the <filename>meta/cfg/kernel-cache/bsp/&lt;bsp_name&gt;/&lt;bsp-name&gt;-&lt;kernel-type&gt;.scc</filename> file.
                    For example, from the <filename>meta</filename> branch in the
                    <filename>linux-yocto-3.0</filename> kernel, the
                    <filename>meta/cfg/kernel-cache/bsp/cedartrail/cedartrail-standard.scc</filename> file
                    has the following:
                    <literallayout class='monospaced'>
     define KMACHINE cedartrail
     define KTYPE standard
     define KARCH i386

     include ktypes/standard
     branch cedartrail

     include cedartrail.scc
                    </literallayout>
                    You can see that the kernel understands the machine name for
                    the Cedar Trail Board Support Package (BSP) as
                    <filename>cedartrail</filename>.
                </para>

                <para>
                    If you look in the Cedar Trail BSP layer in the
                    <filename>meta-intel</filename>
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-repositories'>Source Repositories</ulink>
                    at <filename>meta-cedartrail/recipes-kernel/linux/linux-yocto_3.0.bbappend</filename>,
                    you will find the following statements among others:
                    <literallayout class='monospaced'>
     COMPATIBLE_MACHINE_cedartrail = "cedartrail"
     KMACHINE_cedartrail  = "cedartrail"
     KBRANCH_cedartrail  = "yocto/standard/cedartrail"
     KERNEL_FEATURES_append_cedartrail += "bsp/cedartrail/cedartrail-pvr-merge.scc"
     KERNEL_FEATURES_append_cedartrail += "cfg/efi-ext.scc"

     COMPATIBLE_MACHINE_cedartrail-nopvr = "cedartrail"
     KMACHINE_cedartrail-nopvr  = "cedartrail"
     KBRANCH_cedartrail-nopvr  = "yocto/standard/cedartrail"
     KERNEL_FEATURES_append_cedartrail-nopvr += " cfg/smp.scc"
                    </literallayout>
                    The <filename>KMACHINE</filename> statements in the kernel's append file make sure that
                    the OpenEmbedded build system and the Yocto Linux kernel understand the same machine
                    names.
                </para>

                <para>
                    This append file uses two <filename>KMACHINE</filename> statements.
                    The first is not really necessary but does ensure that the machine known to the
                    OpenEmbedded build system as <filename>cedartrail</filename> maps to the machine
                    in the kernel also known as <filename>cedartrail</filename>:
                    <literallayout class='monospaced'>
     KMACHINE_cedartrail  = "cedartrail"
                    </literallayout>
                </para>

                <para>
                    The second statement is a good example of why the <filename>KMACHINE</filename> variable
                    is needed.
                    In this example, the OpenEmbedded build system uses the <filename>cedartrail-nopvr</filename>
                    machine name to refer to the Cedar Trail BSP that does not support the proprietary
                    PowerVR driver.
                    The kernel, however, uses the machine name <filename>cedartrail</filename>.
                    Thus, the append file must map the <filename>cedartrail-nopvr</filename> machine name to
                    the kernel's <filename>cedartrail</filename> name:
                    <literallayout class='monospaced'>
     KMACHINE_cedartrail-nopvr  = "cedartrail"
                    </literallayout>
                </para>

                <para>
                    BSPs that ship with the Yocto Project release provide all mappings between the Yocto
                    Project kernel machine names and the OpenEmbedded machine names.
                    Be sure to use the <filename>KMACHINE</filename> if you create a BSP and the machine
                    name you use is different than that used in the kernel.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-KTYPE'><glossterm>KTYPE</glossterm>
            <glossdef>
                <para>
                    Defines the kernel type to be used in assembling the
                    configuration.
                    The linux-yocto recipes define "standard", "tiny",
                    and "preempt-rt" kernel types.
                    See the
                    "<ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;#kernel-types'>Kernel Types</ulink>"
                    section in the Yocto Project Linux Kernel Development
                    Manual for more information on kernel types.
                </para>

                <para>
                    You define the <filename>KTYPE</filename> variable in the
                    <ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;#bsp-descriptions'>BSP Descriptions</ulink>.
                    The value you use must match the value used for the
                    <link linkend='var-LINUX_KERNEL_TYPE'><filename>LINUX_KERNEL_TYPE</filename></link>
                    value used by the kernel recipe.
                </para>
            </glossdef>
        </glossentry>
   </glossdiv>

    <glossdiv id='var-glossary-l'><title>L</title>

        <glossentry id='var-LABELS'><glossterm>LABELS</glossterm>
            <glossdef>
                <para>
                    Provides a list of targets for automatic configuration.
                </para>

                <para>
                    See the
                    <link linkend='ref-classes-grub-efi'><filename>grub-efi</filename></link>
                    class for more information on how this variable is used.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-LAYERDEPENDS'><glossterm>LAYERDEPENDS</glossterm>
            <glossdef>
                <para>Lists the layers that this recipe depends upon, separated by spaces.
                    Optionally, you can specify a specific layer version for a dependency
                    by adding it to the end of the layer name with a colon, (e.g. "anotherlayer:3"
                    to be compared against
                    <link linkend='var-LAYERVERSION'><filename>LAYERVERSION</filename></link><filename>_anotherlayer</filename>
                    in this case).
                    An error will be produced if any dependency is missing or
                    the version numbers do not match exactly (if specified).
                    This variable is used in the <filename>conf/layer.conf</filename> file
                    and must be suffixed with the name of the specific layer (e.g.
                    <filename>LAYERDEPENDS_mylayer</filename>).</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-LAYERDIR'><glossterm>LAYERDIR</glossterm>
            <glossdef>
                <para>When used inside the <filename>layer.conf</filename> configuration
                    file, this variable provides the path of the current layer.
                    This variable is not available outside of <filename>layer.conf</filename>
                    and references are expanded immediately when parsing of the file completes.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-LAYERVERSION'><glossterm>LAYERVERSION</glossterm>
            <glossdef>
                <para>Optionally specifies the version of a layer as a single number.
                    You can use this within
                    <link linkend='var-LAYERDEPENDS'><filename>LAYERDEPENDS</filename></link>
                    for another layer in order to depend on a specific version
                    of the layer.
                    This variable is used in the <filename>conf/layer.conf</filename> file
                    and must be suffixed with the name of the specific layer (e.g.
                    <filename>LAYERVERSION_mylayer</filename>).</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-LDFLAGS'><glossterm>LDFLAGS</glossterm>
            <glossdef>
                <para>
                    Specifies the flags to pass to the linker.
                    This variable is exported to an environment
                    variable and thus made visible to the software being
                    built during the compilation step.
                </para>

                <para>
                    Default initialization for <filename>LDFLAGS</filename>
                    varies depending on what is being built:
                    <itemizedlist>
                        <listitem><para>
                            <link linkend='var-TARGET_LDFLAGS'><filename>TARGET_LDFLAGS</filename></link>
                            when building for the target
                            </para></listitem>
                        <listitem><para>
                            <link linkend='var-BUILD_LDFLAGS'><filename>BUILD_LDFLAGS</filename></link>
                            when building for the build host (i.e.
                            <filename>-native</filename>)
                            </para></listitem>
                        <listitem><para>
                            <link linkend='var-BUILDSDK_LDFLAGS'><filename>BUILDSDK_LDFLAGS</filename></link>
                            when building for an SDK (i.e.
                            <filename>nativesdk-</filename>)
                            </para></listitem>
                    </itemizedlist>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-LEAD_SONAME'><glossterm>LEAD_SONAME</glossterm>
            <glossdef>
                <para>
                    Specifies the lead (or primary) compiled library file
                    (<filename>.so</filename>) that the
                    <link linkend='ref-classes-debian'><filename>debian</filename></link>
                    class applies its naming policy to given a recipe that
                    packages multiple libraries.
                </para>

                <para>
                    This variable works in conjunction with the
                    <filename>debian</filename> class.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-LIC_FILES_CHKSUM'><glossterm>LIC_FILES_CHKSUM</glossterm>
            <glossdef>
                <para>Checksums of the license text in the recipe source code.</para>
                <para>This variable tracks changes in license text of the source
                    code files.
                    If the license text is changed, it will trigger a build
                    failure, which gives the developer an opportunity to review any
                    license change.</para>
                <para>
                    This variable must be defined for all recipes (unless
                    <link linkend='var-LICENSE'><filename>LICENSE</filename></link>
                    is set to "CLOSED").</para>
                <para>For more information, see the
                    "<link linkend='usingpoky-configuring-LIC_FILES_CHKSUM'>
                    Tracking License Changes</link>" section.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-LICENSE'><glossterm>LICENSE</glossterm>
            <glossdef>
                <para>
                    The list of source licenses for the recipe.
                    Follow these rules:
                    <itemizedlist>
                        <listitem><para>Do not use spaces within individual
                            license names.</para></listitem>
                        <listitem><para>Separate license names using
                            | (pipe) when there is a choice between licenses.
                            </para></listitem>
                        <listitem><para>Separate license names using
                            &amp; (ampersand) when multiple licenses exist
                            that cover different parts of the source.
                            </para></listitem>
                        <listitem><para>You can use spaces between license
                            names.</para></listitem>
                        <listitem><para>For standard licenses, use the names
                            of the files in
                            <filename>meta/files/common-licenses/</filename>
                            or the
                            <link linkend='var-SPDXLICENSEMAP'><filename>SPDXLICENSEMAP</filename></link>
                            flag names defined in
                            <filename>meta/conf/licenses.conf</filename>.
                            </para></listitem>
                    </itemizedlist>
                </para>

                <para>
                    Here are some examples:
                    <literallayout class='monospaced'>
     LICENSE = "LGPLv2.1 | GPLv3"
     LICENSE = "MPL-1 &amp; LGPLv2.1"
     LICENSE = "GPLv2+"
                    </literallayout>
                    The first example is from the recipes for Qt, which the user
                    may choose to distribute under either the LGPL version
                    2.1 or GPL version 3.
                    The second example is from Cairo where two licenses cover
                    different parts of the source code.
                    The final example is from <filename>sysstat</filename>,
                    which presents a single license.
                </para>

                <para>
                    You can also specify licenses on a per-package basis to
                    handle situations where components of the output have
                    different licenses.
                    For example, a piece of software whose code is
                    licensed under GPLv2 but has accompanying documentation
                    licensed under the GNU Free Documentation License 1.2 could
                    be specified as follows:
                    <literallayout class='monospaced'>
     LICENSE = "GFDL-1.2 &amp; GPLv2"
     LICENSE_${PN} = "GPLv2"
     LICENSE_${PN}-doc = "GFDL-1.2"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-LICENSE_FLAGS'><glossterm>LICENSE_FLAGS</glossterm>
            <glossdef>
                <para>
                    Specifies additional flags for a recipe you must
                    whitelist through
                    <link linkend='var-LICENSE_FLAGS_WHITELIST'><filename>LICENSE_FLAGS_WHITELIST</filename></link>
                    in order to allow the recipe to be built.
                    When providing multiple flags, separate them with
                    spaces.
                </para>

                <para>
                    This value is independent of
                    <link linkend='var-LICENSE'><filename>LICENSE</filename></link>
                    and is typically used to mark recipes that might
                    require additional licenses in order to be used in a
                    commercial product.
                    For more information, see the
                    "<link linkend='enabling-commercially-licensed-recipes'>Enabling Commercially Licensed Recipes</link>"
                    section.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-LICENSE_FLAGS_WHITELIST'><glossterm>LICENSE_FLAGS_WHITELIST</glossterm>
            <glossdef>
                <para>
                    Lists license flags that when specified in
                    <link linkend='var-LICENSE_FLAGS'><filename>LICENSE_FLAGS</filename></link>
                    within a recipe should not prevent that recipe from being
                    built.
                    This practice is otherwise known as "whitelisting"
                    license flags.
                    For more information, see the
                    <link linkend='enabling-commercially-licensed-recipes'>Enabling Commercially Licensed Recipes</link>"
                    section.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-LICENSE_PATH'><glossterm>LICENSE_PATH</glossterm>
            <glossdef>
                <para>Path to additional licenses used during the build.
                    By default, the OpenEmbedded build system uses <filename>COMMON_LICENSE_DIR</filename>
                    to define the directory that holds common license text used during the build.
                    The <filename>LICENSE_PATH</filename> variable allows you to extend that
                    location to other areas that have additional licenses:
                    <literallayout class='monospaced'>
     LICENSE_PATH += "<replaceable>path-to-additional-common-licenses</replaceable>"
                    </literallayout></para>
            </glossdef>
        </glossentry>

        <glossentry id='var-LINUX_KERNEL_TYPE'><glossterm>LINUX_KERNEL_TYPE</glossterm>
            <glossdef>
                <para>
                    Defines the kernel type to be used in assembling the
                    configuration.
                    The linux-yocto recipes define "standard", "tiny", and
                    "preempt-rt" kernel types.
                    See the
                    "<ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;#kernel-types'>Kernel Types</ulink>"
                    section in the Yocto Project Linux Kernel Development
                    Manual for more information on kernel types.
                </para>

                <para>
                    If you do not specify a
                    <filename>LINUX_KERNEL_TYPE</filename>, it defaults to
                    "standard".
                    Together with
                    <link linkend='var-KMACHINE'><filename>KMACHINE</filename></link>,
                    the <filename>LINUX_KERNEL_TYPE</filename> variable
                    defines the search
                    arguments used by the kernel tools to find the appropriate
                    description within the kernel
                    <ulink url='&YOCTO_DOCS_DEV_URL;#metadata'>Metadata</ulink>
                    with which to build out the sources and configuration.
                    </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-LINUX_VERSION'><glossterm>LINUX_VERSION</glossterm>
            <glossdef>
                <para>The Linux version from <filename>kernel.org</filename>
                    on which the Linux kernel image being built using the
                    OpenEmbedded build system is based.
                    You define this variable in the kernel recipe.
                    For example, the <filename>linux-yocto-3.4.bb</filename>
                    kernel recipe found in
                    <filename>meta/recipes-kernel/linux</filename>
                    defines the variables as follows:
                    <literallayout class='monospaced'>
     LINUX_VERSION ?= "3.4.24"
                    </literallayout>
                    The <filename>LINUX_VERSION</filename> variable is used to
                    define <link linkend='var-PV'><filename>PV</filename></link>
                    for the recipe:
                    <literallayout class='monospaced'>
     PV = "${LINUX_VERSION}+git${SRCPV}"
                    </literallayout></para>
            </glossdef>
        </glossentry>

        <glossentry id='var-LINUX_VERSION_EXTENSION'><glossterm>LINUX_VERSION_EXTENSION</glossterm>
            <glossdef>
                <para>A string extension compiled into the version
                    string of the Linux kernel built with the OpenEmbedded
                    build system.
                    You define this variable in the kernel recipe.
                    For example, the linux-yocto kernel recipes all define
                    the variable as follows:
                    <literallayout class='monospaced'>
     LINUX_VERSION_EXTENSION ?= "-yocto-${<link linkend='var-LINUX_KERNEL_TYPE'>LINUX_KERNEL_TYPE</link>}"
                    </literallayout>
                    Defining this variable essentially sets the
                    Linux kernel configuration item
                    <filename>CONFIG_LOCALVERSION</filename>, which is visible
                    through the <filename>uname</filename> command.
                    Here is an example that shows the extension assuming it
                    was set as previously shown:
                    <literallayout class='monospaced'>
     $ uname -r
     3.7.0-rc8-custom
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-LOG_DIR'><glossterm>LOG_DIR</glossterm>
            <glossdef>
                <para>
                    Specifies the directory to which the OpenEmbedded build
                    system writes overall log files.
                    The default directory is <filename>${TMPDIR}/log</filename>.
                </para>
                <para>
                    For the directory containing logs specific to each task,
                    see the <link linkend='var-T'><filename>T</filename></link>
                    variable.
                </para>
            </glossdef>
        </glossentry>

    </glossdiv>

    <glossdiv id='var-glossary-m'><title>M</title>

         <glossentry id='var-MACHINE'><glossterm>MACHINE</glossterm>
            <glossdef>
                <para>
                    Specifies the target device for which the image is built.
                    You define <filename>MACHINE</filename> in the
                    <filename>local.conf</filename> file found in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
                    By default, <filename>MACHINE</filename> is set to
                    "qemux86", which is an x86-based architecture machine to
                    be emulated using QEMU:
                    <literallayout class='monospaced'>
     MACHINE ?= "qemux86"
                    </literallayout>
                    The variable corresponds to a machine configuration file of the
                    same name, through which machine-specific configurations are set.
                    Thus, when <filename>MACHINE</filename> is set to "qemux86" there
                    exists the corresponding <filename>qemux86.conf</filename> machine
                    configuration file, which can be found in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>
                    in <filename>meta/conf/machine</filename>.
                </para>

                <para>
                    The list of machines supported by the Yocto Project as
                    shipped include the following:
                    <literallayout class='monospaced'>
     MACHINE ?= "qemuarm"
     MACHINE ?= "qemumips"
     MACHINE ?= "qemuppc"
     MACHINE ?= "qemux86"
     MACHINE ?= "qemux86-64"
     MACHINE ?= "genericx86"
     MACHINE ?= "genericx86-64"
     MACHINE ?= "beaglebone"
     MACHINE ?= "mpc8315e-rdb"
     MACHINE ?= "edgerouter"
                    </literallayout>
                    The last five are Yocto Project reference hardware boards, which
                    are provided in the <filename>meta-yocto-bsp</filename> layer.
                    <note>Adding additional Board Support Package (BSP) layers
                        to your configuration adds new possible settings for
                        <filename>MACHINE</filename>.
                    </note>
                </para>
            </glossdef>
         </glossentry>

         <glossentry id='var-MACHINE_ARCH'><glossterm>MACHINE_ARCH</glossterm>
            <glossdef>
                <para>
                    Specifies the name of the machine-specific architecture.
                    This variable is set automatically from
                    <link linkend='var-MACHINE'><filename>MACHINE</filename></link>
                    or
                    <link linkend='var-TUNE_PKGARCH'><filename>TUNE_PKGARCH</filename></link>.
                    You should not hand-edit the
                    <filename>MACHINE_ARCH</filename> variable.
                </para>
            </glossdef>
         </glossentry>

         <glossentry id='var-MACHINE_ESSENTIAL_EXTRA_RDEPENDS'><glossterm>MACHINE_ESSENTIAL_EXTRA_RDEPENDS</glossterm>
            <glossdef>
                <para>
                    A list of required machine-specific packages to install as part of
                    the image being built.
                    The build process depends on these packages being present.
                    Furthermore, because this is a "machine essential" variable, the list of
                    packages are essential for the machine to boot.
                    The impact of this variable affects images based on
                    <filename>packagegroup-core-boot</filename>,
                    including the <filename>core-image-minimal</filename> image.
                </para>
                <para>
                    This variable is similar to the
                    <filename><link linkend='var-MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS'>MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS</link></filename>
                    variable with the exception that the image being built has a build
                    dependency on the variable's list of packages.
                    In other words, the image will not build if a file in this list is not found.
                </para>
                <para>
                    As an example, suppose the machine for which you are building requires
                    <filename>example-init</filename> to be run during boot to initialize the hardware.
                    In this case, you would use the following in the machine's
                    <filename>.conf</filename> configuration file:
                    <literallayout class='monospaced'>
     MACHINE_ESSENTIAL_EXTRA_RDEPENDS += "example-init"
                    </literallayout>
                </para>
            </glossdef>
         </glossentry>

         <glossentry id='var-MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS'><glossterm>MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS</glossterm>
            <glossdef>
                <para>
                    A list of recommended machine-specific packages to install as part of
                    the image being built.
                    The build process does not depend on these packages being present.
                    However, because this is a "machine essential" variable, the list of
                    packages are essential for the machine to boot.
                    The impact of this variable affects images based on
                    <filename>packagegroup-core-boot</filename>,
                    including the <filename>core-image-minimal</filename> image.
                </para>
                <para>
                    This variable is similar to the
                    <filename><link linkend='var-MACHINE_ESSENTIAL_EXTRA_RDEPENDS'>MACHINE_ESSENTIAL_EXTRA_RDEPENDS</link></filename>
                    variable with the exception that the image being built does not have a build
                    dependency on the variable's list of packages.
                    In other words, the image will still build if a package in this list is not found.
                    Typically, this variable is used to handle essential kernel modules, whose
                    functionality may be selected to be built into the kernel rather than as a module,
                    in which case a package will not be produced.
                </para>
                <para>
                    Consider an example where you have a custom kernel where a specific touchscreen
                    driver is required for the machine to be usable.
                    However, the driver can be built as a module or
                    into the kernel depending on the kernel configuration.
                    If the driver is built as a module, you want it to be installed.
                    But, when the driver is built into the kernel, you still want the
                    build to succeed.
                    This variable sets up a "recommends" relationship so that in the latter case,
                    the build will not fail due to the missing package.
                    To accomplish this, assuming the package for the module was called
                    <filename>kernel-module-ab123</filename>, you would use the
                    following in the machine's <filename>.conf</filename> configuration
                    file:
                    <literallayout class='monospaced'>
     MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS += "kernel-module-ab123"
                    </literallayout>
                </para>
                <para>
                    Some examples of these machine essentials are flash, screen, keyboard, mouse,
                    or touchscreen drivers (depending on the machine).
                </para>
            </glossdef>
        </glossentry>

         <glossentry id='var-MACHINE_EXTRA_RDEPENDS'><glossterm>MACHINE_EXTRA_RDEPENDS</glossterm>
            <glossdef>
                <para>
                    A list of machine-specific packages to install as part of the
                    image being built that are not essential for the machine to boot.
                    However, the build process for more fully-featured images
                    depends on the packages being present.
                </para>
                <para>
                    This variable affects all images based on
                    <filename>packagegroup-base</filename>, which does not include the
                    <filename>core-image-minimal</filename> or <filename>core-image-full-cmdline</filename>
                    images.
                </para>
                <para>
                    The variable is similar to the
                    <filename><link linkend='var-MACHINE_EXTRA_RRECOMMENDS'>MACHINE_EXTRA_RRECOMMENDS</link></filename>
                    variable with the exception that the image being built has a build
                    dependency on the variable's list of packages.
                    In other words, the image will not build if a file in this list is not found.
                </para>
                <para>
                    An example is a machine that has WiFi capability but is not
                    essential for the machine to boot the image.
                    However, if you are building a more fully-featured image, you want to enable
                    the WiFi.
                    The package containing the firmware for the WiFi hardware is always
                    expected to exist, so it is acceptable for the build process to depend upon
                    finding the package.
                    In this case, assuming the package for the firmware was called
                    <filename>wifidriver-firmware</filename>, you would use the following in the
                    <filename>.conf</filename> file for the machine:
                    <literallayout class='monospaced'>
     MACHINE_EXTRA_RDEPENDS += "wifidriver-firmware"
                    </literallayout>
                </para>
            </glossdef>
         </glossentry>

         <glossentry id='var-MACHINE_EXTRA_RRECOMMENDS'><glossterm>MACHINE_EXTRA_RRECOMMENDS</glossterm>
            <glossdef>
                <para>
                    A list of machine-specific packages to install as part of the
                    image being built that are not essential for booting the machine.
                    The image being built has no build dependency on this list of packages.
                </para>
                <para>
                    This variable affects only images based on
                    <filename>packagegroup-base</filename>, which does not include the
                    <filename>core-image-minimal</filename> or <filename>core-image-full-cmdline</filename>
                    images.
                </para>
                <para>
                    This variable is similar to the
                    <filename><link linkend='var-MACHINE_EXTRA_RDEPENDS'>MACHINE_EXTRA_RDEPENDS</link></filename>
                    variable with the exception that the image being built does not have a build
                    dependency on the variable's list of packages.
                    In other words, the image will build if a file in this list is not found.
                </para>
                <para>
                    An example is a machine that has WiFi capability but is not essential
                    For the machine to boot the image.
                    However, if you are building a more fully-featured image, you want to enable
                    WiFi.
                    In this case, the package containing the WiFi kernel module will not be produced
                    if the WiFi driver is built into the kernel, in which case you still want the
                    build to succeed instead of failing as a result of the package not being found.
                    To accomplish this, assuming the package for the module was called
                    <filename>kernel-module-examplewifi</filename>, you would use the
                    following in the <filename>.conf</filename> file for the machine:
                    <literallayout class='monospaced'>
     MACHINE_EXTRA_RRECOMMENDS += "kernel-module-examplewifi"
                    </literallayout>
                </para>
            </glossdef>
         </glossentry>

         <glossentry id='var-MACHINE_FEATURES'><glossterm>MACHINE_FEATURES</glossterm>
            <glossdef>
                <para>
                    Specifies the list of hardware features the
                    <link linkend='var-MACHINE'><filename>MACHINE</filename></link> is capable
                    of supporting.
                    For related information on enabling features, see the
                    <link linkend='var-DISTRO_FEATURES'><filename>DISTRO_FEATURES</filename></link>,
                    <link linkend='var-COMBINED_FEATURES'><filename>COMBINED_FEATURES</filename></link>,
                    and
                    <link linkend='var-IMAGE_FEATURES'><filename>IMAGE_FEATURES</filename></link>
                    variables.
                </para>

                <para>
                    For a list of hardware features supported by the Yocto
                    Project as shipped, see the
                    "<link linkend='ref-features-machine'>Machine Features</link>"
                    section.
                </para>
            </glossdef>
         </glossentry>

        <glossentry id='var-MACHINE_FEATURES_BACKFILL'><glossterm>MACHINE_FEATURES_BACKFILL</glossterm>
            <glossdef>
                <para>Features to be added to
                    <filename><link linkend='var-MACHINE_FEATURES'>MACHINE_FEATURES</link></filename>
                    if not also present in
                    <filename><link linkend='var-MACHINE_FEATURES_BACKFILL_CONSIDERED'>MACHINE_FEATURES_BACKFILL_CONSIDERED</link></filename>.
                </para>

                <para>
                    This variable is set in the <filename>meta/conf/bitbake.conf</filename> file.
                    It is not intended to be user-configurable.
                    It is best to just reference the variable to see which machine features are
                    being backfilled for all machine configurations.
                    See the "<link linkend='ref-features-backfill'>Feature backfilling</link>" section for
                    more information.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-MACHINE_FEATURES_BACKFILL_CONSIDERED'><glossterm>MACHINE_FEATURES_BACKFILL_CONSIDERED</glossterm>
            <glossdef>
                <para>Features from
                    <filename><link linkend='var-MACHINE_FEATURES_BACKFILL'>MACHINE_FEATURES_BACKFILL</link></filename>
                    that should not be backfilled (i.e. added to
                    <filename><link linkend='var-MACHINE_FEATURES'>MACHINE_FEATURES</link></filename>)
                    during the build.
                    See the "<link linkend='ref-features-backfill'>Feature backfilling</link>" section for
                    more information.
                    </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-MACHINEOVERRIDES'><glossterm>MACHINEOVERRIDES</glossterm>
            <glossdef>
                <para>
                    Lists overrides specific to the current machine.
                    By default, this list includes the value
                    of <filename><link linkend='var-MACHINE'>MACHINE</link></filename>.
                    You can extend the list to apply variable overrides for
                    classes of machines.
                    For example, all QEMU emulated machines (e.g. qemuarm,
                    qemux86, and so forth) include a common file named
                    <filename>meta/conf/machine/include/qemu.inc</filename>
                    that prepends <filename>MACHINEOVERRIDES</filename> with
                    the following variable override:
                    <literallayout class='monospaced'>
    MACHINEOVERRIDES =. "qemuall:"
                    </literallayout>
                    Applying an override like <filename>qemuall</filename>
                    affects all QEMU emulated machines elsewhere.
                    Here is an example from the
                    <filename>connman-conf</filename> recipe:
                    <literallayout class='monospaced'>
    SRC_URI_append_qemuall = "file://wired.config \
                              file://wired-setup \
                             "
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-MAINTAINER'><glossterm>MAINTAINER</glossterm>
            <glossdef>
                <para>The email address of the distribution maintainer.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-MIRRORS'><glossterm>MIRRORS</glossterm>
            <glossdef>
                <para>
                    Specifies additional paths from which the OpenEmbedded
                    build system gets source code.
                    When the build system searches for source code, it first
                    tries the local download directory.
                    If that location fails, the build system tries locations
                    defined by
                    <link linkend='var-PREMIRRORS'><filename>PREMIRRORS</filename></link>,
                    the upstream source, and then locations specified by
                    <filename>MIRRORS</filename> in that order.
                </para>

                <para>
                    Assuming your distribution
                    (<link linkend='var-DISTRO'><filename>DISTRO</filename></link>)
                    is "poky", the default value for
                    <filename>MIRRORS</filename> is defined in the
                    <filename>conf/distro/poky.conf</filename> file in the
                    <filename>meta-yocto</filename> Git repository.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-MLPREFIX'><glossterm>MLPREFIX</glossterm>
            <glossdef>
                <para>
                    Specifies a prefix has been added to
                    <link linkend='var-PN'><filename>PN</filename></link> to create a special version
                    of a recipe or package, such as a Multilib version.
                    The variable is used in places where the prefix needs to be
                    added to or removed from a the name (e.g. the
                    <link linkend='var-BPN'><filename>BPN</filename></link> variable).
                    <filename>MLPREFIX</filename> gets set when a prefix has been
                    added to <filename>PN</filename>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-module_autoload'><glossterm>module_autoload</glossterm>
            <glossdef>
                <para>
                    This variable has been replaced by the
                    <filename>KERNEL_MODULE_AUTOLOAD</filename> variable.
                    You should replace all occurrences of
                    <filename>module_autoload</filename> with additions to
                    <filename>KERNEL_MODULE_AUTOLOAD</filename>, for example:
                    <literallayout class='monospaced'>
     module_autoload_rfcomm = "rfcomm"
                    </literallayout>
                    should now be replaced with:
                    <literallayout class='monospaced'>
     KERNEL_MODULE_AUTOLOAD += "rfcomm"
                    </literallayout>
                    See the
                    <link linkend='var-KERNEL_MODULE_AUTOLOAD'><filename>KERNEL_MODULE_AUTOLOAD</filename></link>
                    variable for more information.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-module_conf'><glossterm>module_conf</glossterm>
            <glossdef>
                <para>
                    Specifies
                    <ulink url='http://linux.die.net/man/5/modprobe.d'><filename>modprobe.d</filename></ulink>
                    syntax lines for inclusion in the
                    <filename>/etc/modprobe.d/modname.conf</filename> file.
                </para>

                <para>
                    You can use this variable anywhere that it can be
                    recognized by the kernel recipe or out-of-tree kernel
                    module recipe (e.g. a machine configuration file, a
                    distribution configuration file, an append file for the
                    recipe, or the recipe itself).
                    If you use this variable, you must also be sure to list
                    the module name in the
                    <link linkend='var-KERNEL_MODULE_AUTOLOAD'><filename>KERNEL_MODULE_AUTOLOAD</filename></link>
                    variable.
                </para>

                <para>
                    Here is the general syntax:
                    <literallayout class='monospaced'>
     module_conf_<replaceable>module_name</replaceable> = "<replaceable>modprobe.d-syntax</replaceable>"
                    </literallayout>
                    You must use the kernel module name override.
                </para>

                <para>
                    Run <filename>man modprobe.d</filename> in the shell to
                    find out more information on the exact syntax
                    you want to provide with <filename>module_conf</filename>.
                </para>

                <para>
                    Including <filename>module_conf</filename> causes the
                    OpenEmbedded build system to populate the
                    <filename>/etc/modprobe.d/modname.conf</filename>
                    file with <filename>modprobe.d</filename> syntax lines.
                    Here is an example that adds the options
                    <filename>arg1</filename> and <filename>arg2</filename>
                    to a module named <filename>mymodule</filename>:
                    <literallayout class='monospaced'>
     module_conf_mymodule = "options mymodule arg1=val1 arg2=val2"
                    </literallayout>
                </para>

                <para>
                    For information on how to specify kernel modules to
                    auto-load on boot, see the
                    <link linkend='var-KERNEL_MODULE_AUTOLOAD'><filename>KERNEL_MODULE_AUTOLOAD</filename></link>
                    variable.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-MODULE_IMAGE_BASE_NAME'><glossterm>MODULE_IMAGE_BASE_NAME</glossterm>
            <glossdef>
                <para>
                    The base name of the kernel modules tarball.
                    This variable is set in the
                    <link linkend='ref-classes-kernel'>kernel</link> class
                    as follows:
                    <literallayout class='monospaced'>
     MODULE_IMAGE_BASE_NAME ?= "modules-${PKGE}-${PKGV}-${PKGR}-${MACHINE}-${DATETIME}"
                    </literallayout>
                    See the
                    <link linkend='var-PKGE'><filename>PKGE</filename></link>,
                    <link linkend='var-PKGV'><filename>PKGV</filename></link>,
                    <link linkend='var-PKGR'><filename>PKGR</filename></link>,
                    <link linkend='var-MACHINE'><filename>MACHINE</filename></link>,
                    and
                    <link linkend='var-DATETIME'><filename>DATETIME</filename></link>
                    variables for additional information.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-MODULE_TARBALL_DEPLOY'><glossterm>MODULE_TARBALL_DEPLOY</glossterm>
            <glossdef>
                <para>
                    Controls creation of the <filename>modules-*.tgz</filename>
                    file.
                    Set this variable to "0" to disable creation of this
                    file, which contains all of the kernel modules resulting
                    from a kernel build.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-MULTIMACH_TARGET_SYS'><glossterm>MULTIMACH_TARGET_SYS</glossterm>
            <glossdef>
                <para>
                    Separates files for different machines such that you can build
                    for multiple target machines using the same output directories.
                    See the <link linkend='var-STAMP'><filename>STAMP</filename></link> variable
                    for an example.
                </para>
            </glossdef>
        </glossentry>

    </glossdiv>

    <glossdiv id='var-glossary-n'><title>N</title>

        <glossentry id='var-NATIVELSBSTRING'><glossterm>NATIVELSBSTRING</glossterm>
            <glossdef>
                <para>
                    A string identifying the host distribution.
                    Strings consist of the host distributor ID
                    followed by the release, as reported by the
                    <filename>lsb_release</filename> tool
                    or as read from <filename>/etc/lsb-release</filename>.
                    For example, when running a build on Ubuntu 12.10, the value
                    is "Ubuntu-12.10".
                    If this information is unable to be determined, the value
                    resolves to "Unknown".
                </para>
                <para>
                    This variable is used by default to isolate native shared
                    state packages for different distributions (e.g. to avoid
                    problems with <filename>glibc</filename> version
                    incompatibilities).
                    Additionally, the variable is checked against
                    <link linkend='var-SANITY_TESTED_DISTROS'><filename>SANITY_TESTED_DISTROS</filename></link>
                    if that variable is set.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-NO_RECOMMENDATIONS'><glossterm>NO_RECOMMENDATIONS</glossterm>
            <glossdef>
                <para>
                    Prevents installation of all "recommended-only" packages.
                    Recommended-only packages are packages installed only
                    through the
                    <link linkend='var-RRECOMMENDS'><filename>RRECOMMENDS</filename></link>
                    variable).
                    Setting the <filename>NO_RECOMMENDATIONS</filename> variable
                    to "1" turns this feature on:
                    <literallayout class='monospaced'>
     NO_RECOMMENDATIONS = "1"
                    </literallayout>
                    You can set this variable globally in your
                    <filename>local.conf</filename> file or you can attach it to
                    a specific image recipe by using the recipe name override:
                    <literallayout class='monospaced'>
     NO_RECOMMENDATIONS_pn-<replaceable>target_image</replaceable> = "<replaceable>package_name</replaceable>"
                    </literallayout>
                </para>

                <para>
                    It is important to realize that if you choose to not install
                    packages using this variable and some other packages are
                    dependent on them (i.e. listed in a recipe's
                    <link linkend='var-RDEPENDS'><filename>RDEPENDS</filename></link>
                    variable), the OpenEmbedded build system ignores your
                    request and will install the packages to avoid dependency
                    errors.
                    <note>
                        Some recommended packages might be required for certain
                        system functionality, such as kernel modules.
                        It is up to you to add packages with the
                        <link linkend='var-IMAGE_INSTALL'><filename>IMAGE_INSTALL</filename></link>
                        variable.
                    </note>
                </para>

                <para>
                    Support for this variable exists only when using the
                    IPK and RPM packaging backend.
                    Support does not exist for DEB.
                </para>

                <para>
                    See the
                    <link linkend='var-BAD_RECOMMENDATIONS'><filename>BAD_RECOMMENDATIONS</filename></link>
                    and the
                    <link linkend='var-PACKAGE_EXCLUDE'><filename>PACKAGE_EXCLUDE</filename></link>
                    variables for related information.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-NOHDD'><glossterm>NOHDD</glossterm>
            <glossdef>
                <para>
                    Causes the OpenEmbedded build system to skip building the
                    <filename>.hddimg</filename> image.
                    The <filename>NOHDD</filename> variable is used with the
                    <link linkend='ref-classes-bootimg'><filename>bootimg</filename></link>
                    class.
                    Set the variable to "1" to prevent the
                    <filename>.hddimg</filename> image from being built.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-NOISO'><glossterm>NOISO</glossterm>
            <glossdef>
                <para>
                    Causes the OpenEmbedded build system to skip building the
                    ISO image.
                    The <filename>NOISO</filename> variable is used with the
                    <link linkend='ref-classes-bootimg'><filename>bootimg</filename></link>
                    class.
                    Set the variable to "1" to prevent the ISO image from
                    being built.
                    To enable building an ISO image, set the variable to "0".
                </para>
            </glossdef>
        </glossentry>

    </glossdiv>

    <glossdiv id='var-glossary-o'><title>O</title>

        <glossentry id='var-OE_BINCONFIG_EXTRA_MANGLE'><glossterm>OE_BINCONFIG_EXTRA_MANGLE</glossterm>
            <glossdef>
                <para>
                    When inheriting the
                    <link linkend='ref-classes-binconfig'><filename>binconfig</filename></link>
                    class, this variable
                    specifies additional arguments passed to the "sed" command.
                    The sed command alters any paths in configuration scripts
                    that have been set up during compilation.
                    Inheriting this class results in all paths in these scripts
                    being changed to point into the
                    <filename>sysroots/</filename> directory so that all builds
                    that use the script will use the correct directories
                    for the cross compiling layout.
                </para>

                <para>
                    See the <filename>meta/classes/binconfig.bbclass</filename>
                    in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>
                    for details on how this class applies these additional
                    sed command arguments.
                    For general information on the
                    <filename>binconfig.bbclass</filename> class, see the
                    "<link linkend='ref-classes-binconfig'>Binary Configuration Scripts - <filename>binconfig.bbclass</filename></link>"
                    section.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-OE_IMPORTS'><glossterm>OE_IMPORTS</glossterm>
            <glossdef>
                <para>
                    An internal variable used to tell the OpenEmbedded build
                    system what Python modules to import for every Python
                    function run by the system.
                </para>

                <note>
                    Do not set this variable.
                    It is for internal use only.
                </note>
            </glossdef>
        </glossentry>

        <glossentry id='var-OE_TERMINAL'><glossterm>OE_TERMINAL</glossterm>
            <glossdef>
                <para>
                    Controls how the OpenEmbedded build system spawns
                    interactive terminals on the host development system
                    (e.g. using the BitBake command with the
                    <filename>-c devshell</filename> command-line option).
                    For more information, see the
                    "<ulink url='&YOCTO_DOCS_DEV_URL;#platdev-appdev-devshell'>Using a Development Shell</ulink>" section
                    in the Yocto Project Development Manual.
                 </para>

                 <para>
                    You can use the following values for the
                    <filename>OE_TERMINAL</filename> variable:
                    <literallayout class='monospaced'>
     auto
     gnome
     xfce
     rxvt
     screen
     konsole
     none
                    </literallayout>
                    <note>Konsole support only works for KDE 3.x.
                        Also, "auto" is the default behavior for
                        <filename>OE_TERMINAL</filename></note>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-OEROOT'><glossterm>OEROOT</glossterm>
            <glossdef>
                <para>
                    The directory from which the top-level build environment
                    setup script is sourced.
                    The Yocto Project makes two top-level build environment
                    setup scripts available:
                    <link linkend='structure-core-script'><filename>&OE_INIT_FILE;</filename></link>
                    and
                    <link linkend='structure-memres-core-script'><filename>oe-init-build-env-memres</filename></link>.
                    When you run one of these scripts, the
                    <filename>OEROOT</filename> variable resolves to the
                    directory that contains the script.
                </para>

                <para>
                    For additional information on how this variable is used,
                    see the initialization scripts.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-OLDEST_KERNEL'><glossterm>OLDEST_KERNEL</glossterm>
            <glossdef>
                <para>
                    Declares the oldest version of the Linux kernel that the
                    produced binaries must support.
                    This variable is passed into the build of the Embedded
                    GNU C Library (<filename>glibc</filename>).
                </para>

                <para>
                    The default for this variable comes from the
                    <filename>meta/conf/bitbake.conf</filename> configuration
                    file.
                    You can override this default by setting the variable
                    in a custom distribution configuration file.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-OVERRIDES'><glossterm>OVERRIDES</glossterm>
            <glossdef>
                <para>
                    BitBake uses <filename>OVERRIDES</filename> to control
                    what variables are overridden after BitBake parses
                    recipes and configuration files.
                    You can find more information on how overrides are handled
                    in the
                    "<ulink url='&YOCTO_DOCS_BB_URL;#conditional-syntax-overrides'>Conditional Syntax (Overrides)</ulink>"
                    section of the BitBake User Manual.
                </para>
            </glossdef>
        </glossentry>
    </glossdiv>

    <glossdiv id='var-glossary-p'><title>P</title>

        <glossentry id='var-P'><glossterm>P</glossterm>
            <glossdef>
                <para>The recipe name and version.
                    <filename>P</filename> is comprised of the following:
                    <literallayout class='monospaced'>
     ${PN}-${PV}
                    </literallayout></para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PACKAGE_ARCH'><glossterm>PACKAGE_ARCH</glossterm>
            <glossdef>
                <para>
                    The architecture of the resulting package or packages.
                </para>

                <para>
                    By default, the value of this variable is set to
                    <link linkend='var-TUNE_PKGARCH'><filename>TUNE_PKGARCH</filename></link>
                    when building for the target,
                    <filename>BUILD_ARCH</filename> when building for the
                    build host and "${SDK_ARCH}-${SDKPKGSUFFIX}" when building
                    for the SDK.
                    However, if your recipe's output packages are built
                    specific to the target machine rather than general for
                    the architecture of the machine, you should set
                    <filename>PACKAGE_ARCH</filename> to the value of
                    <link linkend='var-MACHINE_ARCH'><filename>MACHINE_ARCH</filename></link>
                    in the recipe as follows:
                    <literallayout class='monospaced'>
     PACKAGE_ARCH = "${MACHINE_ARCH}"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PACKAGE_ARCHS'><glossterm>PACKAGE_ARCHS</glossterm>
            <glossdef>
                <para>
                    Specifies a list of architectures compatible with
                    the target machine.
                    This variable is set automatically and should not
                    normally be hand-edited.
                    Entries are separated using spaces and listed in order
                    of priority.
                    The default value for
                    <filename>PACKAGE_ARCHS</filename> is "all any noarch
                    ${PACKAGE_EXTRA_ARCHS} ${MACHINE_ARCH}".
                </para>
            </glossdef>
        </glossentry>



        <glossentry id='var-PACKAGE_BEFORE_PN'><glossterm>PACKAGE_BEFORE_PN</glossterm>
            <glossdef>
                <para>Enables easily adding packages to
                <filename><link linkend='var-PACKAGES'>PACKAGES</link></filename>
                before <filename>${<link linkend='var-PN'>PN</link>}</filename>
                so that those added packages can pick up files that would normally be
                included in the default package.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PACKAGE_CLASSES'><glossterm>PACKAGE_CLASSES</glossterm>
            <glossdef>
                <para>
                    This variable, which is set in the
                    <filename>local.conf</filename> configuration file found in
                    the <filename>conf</filename> folder of the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>,
                    specifies the package manager the OpenEmbedded build system
                    uses when packaging data.
                </para>

                <para>
                    You can provide one or more of the following arguments for
                    the variable:
                    <literallayout class='monospaced'>
     PACKAGE_CLASSES ?= "package_rpm package_deb package_ipk package_tar"
                    </literallayout>
                    The build system uses only the first argument in the list
                    as the package manager when creating your image or SDK.
                    However, packages will be created using any additional
                    packaging classes you specify.
                    For example, if you use the following in your
                    <filename>local.conf</filename> file:
                    <literallayout class='monospaced'>
     PACKAGE_CLASSES ?= "package_ipk package_tar"
                    </literallayout>
                    The OpenEmbedded build system uses the IPK package manager
                    to create your image or SDK as well as generating
                    TAR packages.
                </para>

                <para>
                    You cannot specify the
                    <link linkend='ref-classes-package_tar'><filename>package_tar</filename></link>
                    class first in the list.
                    Files using the <filename>.tar</filename> format cannot
                    be used as a substitute packaging format
                    for DEB, RPM, and IPK formatted files for your image or SDK.
                </para>

                <para>
                    For information on packaging and build performance effects
                    as a result of the package manager in use, see the
                    "<link linkend='ref-classes-package'><filename>package.bbclass</filename></link>"
                    section.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PACKAGE_DEBUG_SPLIT_STYLE'><glossterm>PACKAGE_DEBUG_SPLIT_STYLE</glossterm>
            <glossdef>

                <para>
                    Determines how to split up the binary and debug information
                    when creating <filename>*-dbg</filename> packages to be
                    used with the GNU Project Debugger (GDB).
                </para>

                <para>
                    With the
                    <filename>PACKAGE_DEBUG_SPLIT_STYLE</filename> variable,
                    you can control where debug information, which can include
                    or exclude source files, is stored:
                    <itemizedlist>
                        <listitem><para>
                            ".debug": Debug symbol files are placed next
                            to the binary in a <filename>.debug</filename>
                            directory on the target.
                            For example, if a binary is installed into
                            <filename>/bin</filename>, the corresponding debug
                            symbol files are installed in
                            <filename>/bin/.debug</filename>.
                            Source files are placed in
                            <filename>/usr/src/debug</filename>.
                            This is the default behavior.
                            </para></listitem>
                        <listitem><para>
                            "debug-file-directory": Debug symbol files are
                            placed under <filename>/usr/lib/debug</filename>
                            on the target, and separated by the path from where
                            the binary is installed.
                            For example, if a binary is installed in
                            <filename>/bin</filename>, the corresponding debug
                            symbols are installed in
                            <filename>/usr/lib/debug/bin</filename>.
                            Source files are placed in
                            <filename>/usr/src/debug</filename>.
                            </para></listitem>
                        <listitem><para>
                            "debug-without-src": The same behavior as
                            ".debug" previously described with the exception
                            that no source files are installed.
                            </para></listitem>.
                    </itemizedlist>
                </para>

                <para>
                    You can find out more about debugging using GDB by reading
                    the
                    "<ulink url='&YOCTO_DOCS_DEV_URL;#platdev-gdb-remotedebug'>Debugging With the GNU Project Debugger (GDB) Remotely</ulink>"
                    section in the Yocto Project Development Manual.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PACKAGE_EXCLUDE'><glossterm>PACKAGE_EXCLUDE</glossterm>
            <glossdef>
                <para>
                    Lists packages that should not be installed into an image.
                    For example:
                    <literallayout class='monospaced'>
     PACKAGE_EXCLUDE = "<replaceable>package_name</replaceable> <replaceable>package_name</replaceable> <replaceable>package_name</replaceable> ..."
                    </literallayout>
                    You can set this variable globally in your
                    <filename>local.conf</filename> file or you can attach it to
                    a specific image recipe by using the recipe name override:
                    <literallayout class='monospaced'>
     PACKAGE_EXCLUDE_pn-<replaceable>target_image</replaceable> = "<replaceable>package_name</replaceable>"
                    </literallayout>
                </para>

                <para>
                    If you choose to not install
                    a package using this variable and some other package is
                    dependent on it (i.e. listed in a recipe's
                    <link linkend='var-RDEPENDS'><filename>RDEPENDS</filename></link>
                    variable), the OpenEmbedded build system generates a fatal
                    installation error.
                    Because the build system halts the process with a fatal
                    error, you can use the variable with an iterative
                    development process to remove specific components from a
                    system.
                </para>

                <para>
                    Support for this variable exists only when using the
                    IPK and RPM packaging backend.
                    Support does not exist for DEB.
                </para>

                <para>
                    See the
                    <link linkend='var-NO_RECOMMENDATIONS'><filename>NO_RECOMMENDATIONS</filename></link>
                    and the
                    <link linkend='var-BAD_RECOMMENDATIONS'><filename>BAD_RECOMMENDATIONS</filename></link>
                    variables for related information.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PACKAGE_EXTRA_ARCHS'><glossterm>PACKAGE_EXTRA_ARCHS</glossterm>
            <glossdef>
                <para>Specifies the list of architectures compatible with the device CPU.
                    This variable is useful when you build for several different devices that use
                    miscellaneous processors such as XScale and ARM926-EJS).</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PACKAGE_GROUP'><glossterm>PACKAGE_GROUP</glossterm>
            <glossdef>

                <para>
                    The <filename>PACKAGE_GROUP</filename> variable has been
                    renamed to
                    <link linkend='var-FEATURE_PACKAGES'><filename>FEATURE_PACKAGES</filename></link>.
                    See the variable description for
                    <filename>FEATURE_PACKAGES</filename> for information.
                </para>

                <para>
                    If if you use the <filename>PACKAGE_GROUP</filename>
                    variable, the OpenEmbedded build system issues a warning
                    message.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PACKAGE_INSTALL'><glossterm>PACKAGE_INSTALL</glossterm>
            <glossdef>
                <para>
                    The final list of packages passed to the package manager
                    for installation into the image.
                </para>

                <para>
                    Because the package manager controls actual installation
                    of all packages, the list of packages passed using
                    <filename>PACKAGE_INSTALL</filename> is not the final list
                    of packages that are actually installed.
                    This variable is internal to the image construction
                    code.
                    Consequently, in general, you should use the
                    <link linkend='var-IMAGE_INSTALL'><filename>IMAGE_INSTALL</filename></link>
                    variable to specify packages for installation.
                    The exception to this is when working with
                    the
                    <link linkend='images-core-image-minimal-initramfs'><filename>core-image-minimal-initramfs</filename></link>
                    image.
                    When working with an initial RAM disk (initramfs)
                    image, use the <filename>PACKAGE_INSTALL</filename>
                    variable.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PACKAGE_PREPROCESS_FUNCS'><glossterm>PACKAGE_PREPROCESS_FUNCS</glossterm>
            <glossdef>
                <para>
                    Specifies a list of functions run to pre-process the
                    <link linkend='var-PKGD'><filename>PKGD</filename></link>
                    directory prior to splitting the files out to individual
                    packages.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PACKAGECONFIG'><glossterm>PACKAGECONFIG</glossterm>
            <glossdef>
                <para>
                    This variable provides a means of enabling or disabling
                    features of a recipe on a per-recipe basis.
                    <filename>PACKAGECONFIG</filename> blocks are defined
                    in recipes when you specify features and then arguments
                    that define feature behaviors.
                    Here is the basic block structure:
                    <literallayout class='monospaced'>
     PACKAGECONFIG ??= "f1 f2 f3 ..."
     PACKAGECONFIG[f1] = "--with-f1,--without-f1,build-deps-f1,rt-deps-f1"
     PACKAGECONFIG[f2] = "--with-f2,--without-f2,build-deps-f2,rt-deps-f2"
     PACKAGECONFIG[f3] = "--with-f3,--without-f3,build-deps-f3,rt-deps-f3"
                    </literallayout>
                    The <filename>PACKAGECONFIG</filename>
                    variable itself specifies a space-separated list of the
                    features to enable.
                    Following the features, you can determine the behavior of
                    each feature by providing up to four order-dependent
                    arguments, which are separated by commas.
                    You can omit any argument you like but must retain the
                    separating commas.
                    The order is important and specifies the following:
                    <orderedlist>
                        <listitem><para>Extra arguments
                            that should be added to the configure script
                            argument list
                            (<link linkend='var-EXTRA_OECONF'><filename>EXTRA_OECONF</filename></link>)
                            if the feature is enabled.</para></listitem>
                        <listitem><para>Extra arguments
                            that should be added to <filename>EXTRA_OECONF</filename>
                            if the feature is disabled.
                            </para></listitem>
                        <listitem><para>Additional build dependencies
                            (<link linkend='var-DEPENDS'><filename>DEPENDS</filename></link>)
                            that should be added if the feature is enabled.
                            </para></listitem>
                        <listitem><para>Additional runtime dependencies
                            (<link linkend='var-RDEPENDS'><filename>RDEPENDS</filename></link>)
                            that should be added if the feature is enabled.
                            </para></listitem>
                    </orderedlist>
                </para>

                <para>
                    Consider the following
                    <filename>PACKAGECONFIG</filename> block taken from the
                    <filename>librsvg</filename> recipe.
                    In this example the feature is <filename>croco</filename>,
                    which has three arguments that determine the feature's
                    behavior.
                    <literallayout class='monospaced'>
     PACKAGECONFIG ??= "croco"
     PACKAGECONFIG[croco] = "--with-croco,--without-croco,libcroco"
                    </literallayout>
                    The <filename>--with-croco</filename> and
                    <filename>libcroco</filename> arguments apply only if
                    the feature is enabled.
                    In this case, <filename>--with-croco</filename> is
                    added to the configure script argument list and
                    <filename>libcroco</filename> is added to
                    <filename><link linkend='var-DEPENDS'>DEPENDS</link></filename>.
                    On the other hand, if the feature is disabled say through
                    a <filename>.bbappend</filename> file in another layer, then
                    the second argument <filename>--without-croco</filename> is
                    added to the configure script rather than
                    <filename>--with-croco</filename>.
                </para>

                <para>
                    The basic <filename>PACKAGECONFIG</filename> structure
                    previously described holds true regardless of whether you
                    are creating a block or changing a block.
                    When creating a block, use the structure inside your
                    recipe.
                </para>

                <para>
                    If you want to change an existing
                    <filename>PACKAGECONFIG</filename> block, you can do so
                    one of two ways:
                    <itemizedlist>
                        <listitem><para><emphasis>Append file:</emphasis>
                            Create an append file named
                            <replaceable>recipename</replaceable><filename>.bbappend</filename>
                            in your layer and override the value of
                            <filename>PACKAGECONFIG</filename>.
                            You can either completely override the variable:
                            <literallayout class='monospaced'>
     PACKAGECONFIG="f4 f5"
                            </literallayout>
                            Or, you can just append the variable:
                            <literallayout class='monospaced'>
     PACKAGECONFIG_append = " f4"
                            </literallayout></para></listitem>
                        <listitem><para><emphasis>Configuration file:</emphasis>
                            This method is identical to changing the block
                            through an append file except you edit your
                            <filename>local.conf</filename> or
                            <filename><replaceable>mydistro</replaceable>.conf</filename> file.
                            As with append files previously described,
                            you can either completely override the variable:
                            <literallayout class='monospaced'>
     PACKAGECONFIG_pn-<replaceable>recipename</replaceable>="f4 f5"
                            </literallayout>
                            Or, you can just amend the variable:
                            <literallayout class='monospaced'>
     PACKAGECONFIG_append_pn-<replaceable>recipename</replaceable> = " f4"
                            </literallayout></para></listitem>
                    </itemizedlist>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PACKAGES'><glossterm>PACKAGES</glossterm>
            <glossdef>
                <para>The list of packages to be created from the recipe.
                    The default value is the following:
                    <literallayout class='monospaced'>
     ${PN}-dbg ${PN}-staticdev ${PN}-dev ${PN}-doc ${PN}-locale ${PACKAGE_BEFORE_PN} ${PN}
                    </literallayout></para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PACKAGESPLITFUNCS'><glossterm>PACKAGESPLITFUNCS</glossterm>
            <glossdef>
                <para>
                    Specifies a list of functions run to perform additional
                    splitting of files into individual packages.
                    Recipes can either prepend to this variable or prepend
                    to the <filename>populate_packages</filename> function
                    in order to perform additional package splitting.
                    In either case, the function should set
                    <link linkend='var-PACKAGES'><filename>PACKAGES</filename></link>,
                    <link linkend='var-FILES'><filename>FILES</filename></link>,
                    <link linkend='var-RDEPENDS'><filename>RDEPENDS</filename></link>
                    and other packaging variables appropriately in order to
                    perform the desired splitting.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PACKAGES_DYNAMIC'><glossterm>PACKAGES_DYNAMIC</glossterm>
            <glossdef>
                <para>
                    A promise that your recipe satisfies runtime dependencies
                    for optional modules that are found in other recipes.
                    <filename>PACKAGES_DYNAMIC</filename>
                    does not actually satisfy the dependencies, it only states that
                    they should be satisfied.
                    For example, if a hard, runtime dependency
                    (<link linkend='var-RDEPENDS'><filename>RDEPENDS</filename></link>)
                    of another package is satisfied
                    at build time through the <filename>PACKAGES_DYNAMIC</filename>
                    variable, but a package with the module name is never actually
                    produced, then the other package will be broken.
                    Thus, if you attempt to include that package in an image,
                    you will get a dependency failure from the packaging system
                    during the
                    <link linkend='ref-tasks-rootfs'><filename>do_rootfs</filename></link>
                    task.
                </para>
                <para>
                    Typically, if there is a chance that such a situation can
                    occur and the package that is not created is valid
                    without the dependency being satisfied, then you should use
                    <link linkend='var-RRECOMMENDS'><filename>RRECOMMENDS</filename></link>
                    (a soft runtime dependency) instead of
                    <filename>RDEPENDS</filename>.
                </para>

                <para>
                    For an example of how to use the <filename>PACKAGES_DYNAMIC</filename>
                    variable when you are splitting packages, see the
                    "<ulink url='&YOCTO_DOCS_DEV_URL;#handling-optional-module-packaging'>Handling Optional Module Packaging</ulink>" section
                    in the Yocto Project Development Manual.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PARALLEL_MAKE'><glossterm>PARALLEL_MAKE</glossterm>
            <glossdef>
                <para>
                    Extra options passed to the <filename>make</filename>
                    command during the
                    <link linkend='ref-tasks-compile'><filename>do_compile</filename></link>
                    task in order to specify parallel compilation on the local
                    build host.
                    This variable is usually in the form "-j &lt;x&gt;",
                    where x represents the maximum number of parallel threads
                    <filename>make</filename> can run.
                </para>

                <para>
                    If your development host supports multiple cores, a good
                    rule of thumb is to set this variable to twice the number
                    of cores on the host.
                    If you do not set <filename>PARALLEL_MAKE</filename>, it
                    defaults to the number of cores your build system has.
                    <note>
                        Individual recipes might clear out this variable if
                        the software being built has problems running its
                        <filename>make</filename> process in parallel.
                    </note>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PARALLEL_MAKEINST'><glossterm>PARALLEL_MAKEINST</glossterm>
            <glossdef>
                <para>
                    Extra options passed to the
                    <filename>make install</filename> command during the
                    <link linkend='ref-tasks-install'><filename>do_install</filename></link>
                    task in order to specify parallel installation.
                    This variable defaults to the value of
                    <link linkend='var-PARALLEL_MAKE'><filename>PARALLEL_MAKE</filename></link>.
                    <note>
                        Individual recipes might clear out this variable if
                        the software being built has problems running its
                        <filename>make install</filename> process in parallel.
                    </note>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PATCHRESOLVE'><glossterm>PATCHRESOLVE</glossterm>
            <glossdef>
                <para>
                    Determines the action to take when a patch fails.
                    You can set this variable to one of two values: "noop" and
                    "user".
                </para>

                <para>
                    The default value of "noop" causes the build to simply fail
                    when the OpenEmbedded build system cannot successfully
                    apply a patch.
                    Setting the value to "user" causes the build system to
                    launch a shell and places you in the right location so that
                    you can manually resolve the conflicts.
                </para>

                <para>
                    Set this variable in your
                    <filename>local.conf</filename> file.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PATCHTOOL'><glossterm>PATCHTOOL</glossterm>
            <glossdef>
                <para>
                    Specifies the utility used to apply patches for a recipe
                    during the
                    <link linkend='ref-tasks-patch'><filename>do_patch</filename></link>
                    task.
                    You can specify one of three utilities: "patch", "quilt", or
                    "git".
                    The default utility used is "quilt" except for the
                    quilt-native recipe itself.
                    Because the quilt tool is not available at the
                    time quilt-native is being patched, it uses "patch".
                </para>

                <para>
                    If you wish to use an alternative patching tool, set the
                    variable in the recipe using one of the following:
                    <literallayout class='monospaced'>
     PATCHTOOL = "patch"
     PATCHTOOL = "quilt"
     PATCHTOOL = "git"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PE'><glossterm>PE</glossterm>
            <glossdef>
                <para>
                    The epoch of the recipe.
                    By default, this variable is unset.
                    The variable is used to make upgrades possible when the
                    versioning scheme changes in some backwards incompatible
                    way.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PF'><glossterm>PF</glossterm>
            <glossdef>
                <para>Specifies the recipe or package name and includes all version and revision
                    numbers (i.e. <filename>glibc-2.13-r20+svnr15508/</filename> and
                    <filename>bash-4.2-r1/</filename>).
                    This variable is comprised of the following:
                    <literallayout class='monospaced'>
     ${<link linkend='var-PN'>PN</link>}-${<link linkend='var-EXTENDPE'>EXTENDPE</link>}${<link linkend='var-PV'>PV</link>}-${<link linkend='var-PR'>PR</link>}
                    </literallayout></para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PIXBUF_PACKAGES'><glossterm>PIXBUF_PACKAGES</glossterm>
            <glossdef>
                <para>
                    When inheriting the
                    <link linkend='ref-classes-pixbufcache'><filename>pixbufcache</filename></link>
                    class, this variable identifies packages that contain
                    the pixbuf loaders used with
                    <filename>gdk-pixbuf</filename>.
                    By default, the <filename>pixbufcache</filename> class
                    assumes that the loaders are in the recipe's main package
                    (i.e. <filename>${</filename><link linkend='var-PN'><filename>PN</filename></link><filename>}</filename>).
                    Use this variable if the loaders you need are in a package
                    other than that main package.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PKG'><glossterm>PKG</glossterm>
            <glossdef>
                <para>
                    The name of the resulting package created by the
                    OpenEmbedded build system.
                    <note>
                        When using the <filename>PKG</filename> variable, you
                        must use a package name override.
                    </note>
                    For example, when the
                    <link linkend='ref-classes-debian'><filename>debian</filename></link>
                    class renames the output package, it does so by setting
                    <filename>PKG_<replaceable>packagename</replaceable></filename>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PKGD'><glossterm>PKGD</glossterm>
            <glossdef>
                <para>
                    Points to the destination directory for files to be
                    packaged before they are split into individual packages.
                    This directory defaults to the following:
                    <literallayout class='monospaced'>
     ${WORKDIR}/package
                    </literallayout>
                    Do not change this default.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PKGDATA_DIR'><glossterm>PKGDATA_DIR</glossterm>
            <glossdef>
                <para>
                    Points to a shared, global-state directory that holds data
                    generated during the packaging process.
                    During the packaging process, the
                    <link linkend='ref-tasks-packagedata'><filename>do_packagedata</filename></link>
                    task packages data for each recipe and installs it into
                    this temporary, shared area.
                    This directory defaults to the following:
                    <literallayout class='monospaced'>
     ${STAGING_DIR_HOST}/pkgdata
                    </literallayout>
                    Do not change this default.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PKGDEST'><glossterm>PKGDEST</glossterm>
            <glossdef>
                <para>
                    Points to the parent directory for files to be packaged
                    after they have been split into individual packages.
                    This directory defaults to the following:
                    <literallayout class='monospaced'>
     ${WORKDIR}/packages-split
                    </literallayout>
                    Under this directory, the build system creates
                    directories for each package specified in
                    <link linkend='var-PACKAGES'><filename>PACKAGES</filename></link>.
                    Do not change this default.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PKGDESTWORK'><glossterm>PKGDESTWORK</glossterm>
            <glossdef>
                <para>
                    Points to a temporary work area used by the
                    <link linkend='ref-tasks-package'><filename>do_package</filename></link>
                    task to write output from the
                    <link linkend='ref-tasks-packagedata'><filename>do_packagedata</filename></link>
                    task.
                    The <filename>PKGDESTWORK</filename> location defaults to
                    the following:
                    <literallayout class='monospaced'>
     ${WORKDIR}/pkgdata
                    </literallayout>
                    The <filename>do_packagedata</filename> task then packages
                    the data in the temporary work area and installs it into a
                    shared directory pointed to by
                    <link linkend='var-PKGDATA_DIR'><filename>PKGDATA_DIR</filename></link>.
                </para>

                <para>
                    Do not change this default.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PKGE'><glossterm>PKGE</glossterm>
            <glossdef>
                <para>
                    The epoch of the output package built by the
                    OpenEmbedded build system.
                    By default, <filename>PKGE</filename> is set to
                    <link linkend='var-PE'><filename>PE</filename></link>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PKGR'><glossterm>PKGR</glossterm>
            <glossdef>
                <para>
                    The revision of the output package built by the
                    OpenEmbedded build system.
                    By default, <filename>PKGR</filename> is set to
                    <link linkend='var-PR'><filename>PR</filename></link>.
                    </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PKGV'><glossterm>PKGV</glossterm>
            <glossdef>
                <para>
                    The version of the output package built by the
                    OpenEmbedded build system.
                    By default, <filename>PKGV</filename> is set to
                    <link linkend='var-PV'><filename>PV</filename></link>.
                 </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PN'><glossterm>PN</glossterm>
            <glossdef>
                <para>This variable can have two separate functions depending on the context: a recipe
                    name or a resulting package name.</para>
                <para><filename>PN</filename> refers to a recipe name in the context of a file used
                    by the OpenEmbedded build system as input to create a package.
                    The name is normally extracted from the recipe file name.
                    For example, if the recipe is named
                    <filename>expat_2.0.1.bb</filename>, then the default value of <filename>PN</filename>
                    will be "expat".</para>
                <para>
                    The variable refers to a package name in the context of a file created or produced by the
                    OpenEmbedded build system.</para>
                <para>If applicable, the <filename>PN</filename> variable also contains any special
                    suffix or prefix.
                    For example, using <filename>bash</filename> to build packages for the native
                    machine, <filename>PN</filename> is <filename>bash-native</filename>.
                    Using <filename>bash</filename> to build packages for the target and for Multilib,
                    <filename>PN</filename> would be <filename>bash</filename> and
                    <filename>lib64-bash</filename>, respectively.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PNBLACKLIST'><glossterm>PNBLACKLIST</glossterm>
            <glossdef>
                <para>
                    Lists recipes you do not want the OpenEmbedded build system
                    to build.
                    This variable works in conjunction with the
                    <link linkend='ref-classes-blacklist'><filename>blacklist</filename></link>
                    class, which the recipe must inherit globally.
                </para>

                <para>
                    To prevent a recipe from being built, inherit the class
                    globally and use the variable in your
                    <filename>local.conf</filename> file.
                    Here is an example that prevents
                    <filename>myrecipe</filename> from being built:
                    <literallayout class='monospaced'>
     INHERIT += "blacklist"
     PNBLACKLIST[myrecipe] = "Not supported by our organization."
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PR'><glossterm>PR</glossterm>
            <glossdef>
                <para>
                    The revision of the recipe.
                    The default value for this variable is "r0".
                    </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PREFERRED_PROVIDER'><glossterm>PREFERRED_PROVIDER</glossterm>
            <glossdef>
                <para>
                    If multiple recipes provide an item, this variable
                    determines which recipe should be given preference.
                    You should always suffix the variable with the name of the
                    provided item, and you should set it to the
                    <link linkend='var-PN'><filename>PN</filename></link>
                    of the recipe to which you want to give precedence.
                    Some examples:
                    <literallayout class='monospaced'>
     PREFERRED_PROVIDER_virtual/kernel ?= "linux-yocto"
     PREFERRED_PROVIDER_virtual/xserver = "xserver-xf86"
     PREFERRED_PROVIDER_virtual/libgl ?= "mesa"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PREFERRED_VERSION'><glossterm>PREFERRED_VERSION</glossterm>
            <glossdef>
                <para>
                    If there are multiple versions of recipes available, this
                    variable determines which recipe should be given preference.
                    You must always suffix the variable with the
                    <link linkend='var-PN'><filename>PN</filename></link>
                    you want to select, and you should set the
                    <link linkend='var-PV'><filename>PV</filename></link>
                    accordingly for precedence.
                    You can use the "<filename>%</filename>" character as a
                    wildcard to match any number of characters, which can be
                    useful when specifying versions that contain long revision
                    numbers that could potentially change.
                    Here are two examples:
                    <literallayout class='monospaced'>
     PREFERRED_VERSION_python = "2.7.3"
     PREFERRED_VERSION_linux-yocto = "3.10%"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PREMIRRORS'><glossterm>PREMIRRORS</glossterm>
            <glossdef>
                <para>
                    Specifies additional paths from which the OpenEmbedded
                    build system gets source code.
                    When the build system searches for source code, it first
                    tries the local download directory.
                    If that location fails, the build system tries locations
                    defined by <filename>PREMIRRORS</filename>, the upstream
                    source, and then locations specified by
                    <link linkend='var-MIRRORS'><filename>MIRRORS</filename></link>
                    in that order.
                </para>

                <para>
                    Assuming your distribution
                    (<link linkend='var-DISTRO'><filename>DISTRO</filename></link>)
                    is "poky", the default value for
                    <filename>PREMIRRORS</filename> is defined in the
                    <filename>conf/distro/poky.conf</filename> file in the
                    <filename>meta-yocto</filename> Git repository.
                </para>

                <para>
                    Typically, you could add a specific server for the
                    build system to attempt before any others by adding
                    something like the following to the
                    <filename>local.conf</filename> configuration file in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>:
                    <literallayout class='monospaced'>
     PREMIRRORS_prepend = "\
     git://.*/.* http://www.yoctoproject.org/sources/ \n \
     ftp://.*/.* http://www.yoctoproject.org/sources/ \n \
     http://.*/.* http://www.yoctoproject.org/sources/ \n \
     https://.*/.* http://www.yoctoproject.org/sources/ \n"
                    </literallayout>
                    These changes cause the build system to intercept
                    Git, FTP, HTTP, and HTTPS requests and direct them to
                    the <filename>http://</filename> sources mirror.
                    You can use <filename>file://</filename> URLs to point
                    to local directories or network shares as well.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PRINC'><glossterm>PRINC</glossterm>
            <glossdef>

                <para>
                    The <filename>PRINC</filename> variable has been deprecated
                    and triggers a warning if detected during a build.
                    For
                    <link linkend='var-PR'><filename>PR</filename></link>
                    increments on changes, use the PR service instead.
                    You can find out more about this service in the
                    "<ulink url='&YOCTO_DOCS_DEV_URL;#working-with-a-pr-service'>Working With a PR Service</ulink>"
                    section in the Yocto Project Development Manual.
                </para>
<!--

                <para>
                    Causes the
                    <link linkend='var-PR'><filename>PR</filename></link>
                    variable of <filename>.bbappend</filename> files to
                    dynamically increment.
                    This increment minimizes the impact of layer ordering.
                </para>

                <para>
                    In order to ensure multiple <filename>.bbappend</filename>
                    files can co-exist,
                    <filename>PRINC</filename> should be self-referencing.
                    This variable defaults to 0.
                </para>

                <para>
                    Following is an example that increments
                    <filename>PR</filename> by two:
                    <literallayout class='monospaced'>
     PRINC := "${@int(PRINC) + 2}"
                    </literallayout>
                    It is advisable not to use strings such as ".= '.1'" with the variable because
                    this usage is very sensitive to layer ordering.
                    You should avoid explicit assignments as they cannot
                    adequately represent multiple
                    <filename>.bbappend</filename> files.
                </para>
-->
            </glossdef>
        </glossentry>

        <glossentry id='var-PRIVATE_LIBS'><glossterm>PRIVATE_LIBS</glossterm>
            <glossdef>
                <para>
                    Specifies libraries installed within a recipe that
                    should be ignored by the OpenEmbedded build system's
                    shared library resolver.
                    This variable is typically used when software being
                    built by a recipe has its own private versions of a
                    library normally provided by another recipe.
                    In this case, you would not want the package containing
                    the private libraries to be set as a dependency on other
                    unrelated packages that should instead depend on the
                    package providing the standard version of the library.
                </para>

                <para>
                    Libraries specified in this variable should be specified
                    by their file name.
                    For example, from the Firefox recipe in meta-browser:
                    <literallayout class='monospaced'>
     PRIVATE_LIBS = "libmozjs.so \
                     libxpcom.so \
                     libnspr4.so \
                     libxul.so \
                     libmozalloc.so \
                     libplc4.so \
                     libplds4.so"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PROVIDES'><glossterm>PROVIDES</glossterm>
            <glossdef>
                <para>
                    A list of aliases by which a particular recipe can be
                    known.
                    By default, a recipe's own
                    <filename><link linkend='var-PN'>PN</link></filename>
                    is implicitly already in its <filename>PROVIDES</filename>
                    list.
                    If a recipe uses <filename>PROVIDES</filename>, the
                    additional aliases are synonyms for the recipe and can
                    be useful satisfying dependencies of other recipes during
                    the build as specified by
                    <filename><link linkend='var-DEPENDS'>DEPENDS</link></filename>.
                </para>

                <para>
                    Consider the following example
                    <filename>PROVIDES</filename> statement from a recipe
                    file <filename>libav_0.8.11.bb</filename>:
                    <literallayout class='monospaced'>
     PROVIDES += "libpostproc"
                    </literallayout>
                    The <filename>PROVIDES</filename> statement results in
                    the "libav" recipe also being known as "libpostproc".
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PRSERV_HOST'><glossterm>PRSERV_HOST</glossterm>
            <glossdef>
                <para>
                    The network based
                    <link linkend='var-PR'><filename>PR</filename></link>
                    service host and port.
                </para>

                <para>
                    The <filename>conf/local.conf.sample.extended</filename>
                    configuration file in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>
                    shows how the <filename>PRSERV_HOST</filename> variable is
                    set:
                    <literallayout class='monospaced'>
     PRSERV_HOST = "localhost:0"
                    </literallayout>
                    You must set the variable if you want to automatically
                    start a local
                    <ulink url='&YOCTO_DOCS_DEV_URL;#working-with-a-pr-service'>PR service</ulink>.
                    You can set <filename>PRSERV_HOST</filename> to other
                    values to use a remote PR service.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PTEST_ENABLED'><glossterm>PTEST_ENABLED</glossterm>
            <glossdef>
                <para>
                    Specifies whether or not
                    <ulink url='&YOCTO_DOCS_DEV_URL;#testing-packages-with-ptest'>Package Test</ulink>
                    (ptest) functionality is enabled when building a recipe.
                    You should not set this variable directly.
                    Enabling and disabling building Package Tests
                    at build time should be done by adding "ptest" to (or
                    removing it from)
                    <link linkend='var-DISTRO_FEATURES'><filename>DISTRO_FEATURES</filename></link>.
                 </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PV'><glossterm>PV</glossterm>
            <glossdef>
                <para>
                    The version of the recipe.
                    The version is normally extracted from the recipe filename.
                    For example, if the recipe is named
                    <filename>expat_2.0.1.bb</filename>, then the default value of <filename>PV</filename>
                    will be "2.0.1".
                    <filename>PV</filename> is generally not overridden within
                    a recipe unless it is building an unstable (i.e. development) version from a source code repository
                    (e.g. Git or Subversion).
                 </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PYTHON_ABI'><glossterm>PYTHON_ABI</glossterm>
            <glossdef>
                <para>
                    When used by recipes that inherit the
                    <link linkend='ref-classes-distutils3'><filename>distutils3</filename></link>,
                    <link linkend='ref-classes-setuptools3'><filename>setuptools3</filename></link>,
                    <link linkend='ref-classes-distutils'><filename>distutils</filename></link>,
                    or
                    <link linkend='ref-classes-setuptools'><filename>setuptools</filename></link>
                    classes, denotes the Application Binary Interface (ABI)
                    currently in use for Python.
                    By default, the ABI is "m".
                    You do not have to set this variable as the OpenEmbedded
                    build system sets it for you.
                </para>

                <para>
                    The OpenEmbedded build system uses the ABI to construct
                    directory names used when installing the Python headers
                    and libraries in sysroot
                    (e.g. <filename>.../python3.3m/...</filename>).
                </para>

                <para>
                    Recipes that inherit the
                    <link linkend='ref-classes-distutils'><filename>distutils</filename></link>
                    class during cross-builds also use this variable to
                    locate the headers and libraries of the appropriate Python
                    that the extension is targeting.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-PYTHON_PN'><glossterm>PYTHON_PN</glossterm>
            <glossdef>
                <para>
                    When used by recipes that inherit the
                    <link linkend='ref-classes-distutils3'><filename>distutils3</filename></link>,
                    <link linkend='ref-classes-setuptools3'><filename>setuptools3</filename></link>,
                    <link linkend='ref-classes-distutils'><filename>distutils</filename></link>,
                    or
                    <link linkend='ref-classes-setuptools'><filename>setuptools</filename></link>
                    classes, specifies the major Python version being built.
                    For Python 2.x, <filename>PYTHON_PN</filename> would
                    be "python2".  For Python 3.x, the variable would be
                    "python3".
                    You do not have to set this variable as the
                    OpenEmbedded build system automatically sets it for you.
                </para>

                <para>
                    The variable allows recipes to use common infrastructure
                    such as the following:
                    <literallayout class='monospaced'>
     DEPENDS += "${PYTHON_PN}-native"
                    </literallayout>
                    In the previous example, the version of the dependency
                    is <filename>PYTHON_PN</filename>.
                </para>
            </glossdef>
        </glossentry>

    </glossdiv>

    <glossdiv id='var-glossary-q'><title>Q</title>

        <glossentry id='var-QMAKE_PROFILES'><glossterm>QMAKE_PROFILES</glossterm>
            <glossdef>
                <para>
                    Specifies your own subset of <filename>.pro</filename>
                    files to be built for use with
                    <filename>qmake</filename>.
                    If you do not set this variable, all
                    <filename>.pro</filename> files in the directory pointed to
                    by <link linkend='var-S'><filename>S</filename></link>
                    will be built by default.
                </para>

                <para>
                    This variable is used with recipes that inherit the
                    <link linkend='ref-classes-qmake*'><filename>qmake_base</filename></link>
                    class or other classes that inherit
                    <filename>qmake_base</filename>.
                </para>
            </glossdef>
        </glossentry>

    </glossdiv>

    <glossdiv id='var-glossary-r'><title>R</title>

        <glossentry id='var-RCONFLICTS'><glossterm>RCONFLICTS</glossterm>
            <glossdef>
                <para>
                    The list of packages that conflict with packages.
                    Note that packages will not be installed if conflicting
                    packages are not first removed.
                </para>

                <para>
                   Like all package-controlling variables, you must always use
                   them in conjunction with a package name override.
                   Here is an example:
                   <literallayout class='monospaced'>
     RCONFLICTS_${PN} = "<replaceable>another-conflicting-package-name</replaceable>"
                   </literallayout>
                </para>

                <para>
                    BitBake, which the OpenEmbedded build system uses, supports
                    specifying versioned dependencies.
                    Although the syntax varies depending on the packaging
                    format, BitBake hides these differences from you.
                    Here is the general syntax to specify versions with
                    the <filename>RCONFLICTS</filename> variable:
                    <literallayout class='monospaced'>
     RCONFLICTS_${PN} = "<replaceable>package</replaceable> (<replaceable>operator</replaceable> <replaceable>version</replaceable>)"
                    </literallayout>
                    For <filename>operator</filename>, you can specify the
                    following:
                    <literallayout class='monospaced'>
     =
     &lt;
     &gt;
     &lt;=
     &gt;=
                    </literallayout>
                    For example, the following sets up a dependency on version
                    1.2 or greater of the package <filename>foo</filename>:
                    <literallayout class='monospaced'>
     RCONFLICTS_${PN} = "foo (>= 1.2)"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-RDEPENDS'><glossterm>RDEPENDS</glossterm>
            <glossdef>
                <para>
                    Lists a package's runtime dependencies (i.e. other packages)
                    that must be installed in order for the built package to run
                    correctly.
                    If a package in this list cannot be found during the build,
                    you will get a build error.
                </para>

                <para>
                    When you use the <filename>RDEPENDS</filename> variable
                    in a recipe, you are essentially stating that the recipe's
                    <link linkend='ref-tasks-build'><filename>do_build</filename></link>
                    task depends on the existence of a specific package.
                    Consider this simple example for two recipes named "a" and
                    "b" that produce similarly named IPK packages.
                    In this example, the <filename>RDEPENDS</filename>
                    statement appears in the "a" recipe:
                    <literallayout class='monospaced'>
     RDEPENDS_${PN} = "b"
                    </literallayout>
                    Here, the dependency is such that the
                    <filename>do_build</filename> task for recipe "a" depends
                    on the
                    <link linkend='ref-tasks-package_write_ipk'><filename>do_package_write_ipk</filename></link>
                    task of recipe "b".
                    This means the package file for "b" must be available when
                    the output for recipe "a" has been completely built.
                    More importantly, package "a" will be marked as depending
                    on package "b" in a manner that is understood by the
                    package manager.
                </para>

                <para>
                    The names of the packages you list within
                    <filename>RDEPENDS</filename> must be the names of other
                    packages - they cannot be recipe names.
                    Although package names and recipe names usually match,
                    the important point here is that you are
                    providing package names within the
                    <filename>RDEPENDS</filename> variable.
                    For an example of the default list of packages created from
                    a recipe, see the
                    <link linkend='var-PACKAGES'><filename>PACKAGES</filename></link>
                    variable.
                </para>

                <para>
                    Because the <filename>RDEPENDS</filename> variable applies
                    to packages being built, you should always use the variable
                    in a form with an attached package name.
                    For example, suppose you are building a development package
                    that depends on the <filename>perl</filename> package.
                    In this case, you would use the following
                    <filename>RDEPENDS</filename> statement:
                    <literallayout class='monospaced'>
     RDEPENDS_${PN}-dev += "perl"
                    </literallayout>
                    In the example, the development package depends on
                    the <filename>perl</filename> package.
                    Thus, the <filename>RDEPENDS</filename> variable has the
                    <filename>${PN}-dev</filename> package name as part of the
                    variable.
                </para>

                <para>
                    The package name you attach to the
                    <filename>RDEPENDS</filename> variable must appear
                    as it would in the <filename>PACKAGES</filename>
                    namespace before any renaming of the output package by
                    classes like
                    <link linkend='ref-classes-debian'><filename>debian</filename></link>.
                </para>

                <para>
                    In many cases you do not need to explicitly add
                    runtime dependencies using
                    <filename>RDEPENDS</filename> since some automatic
                    handling occurs:
                    <itemizedlist>
                        <listitem><para><emphasis><filename>shlibdeps</filename></emphasis>:  If
                            a runtime package contains a shared library
                            (<filename>.so</filename>), the build
                            processes the library in order to determine other
                            libraries to which it is dynamically linked.
                            The build process adds these libraries to
                            <filename>RDEPENDS</filename> when creating the runtime
                            package.</para></listitem>
                        <listitem><para><emphasis><filename>pcdeps</filename></emphasis>:  If
                            the package ships a <filename>pkg-config</filename>
                            information file, the build process uses this file
                            to add items to the <filename>RDEPENDS</filename>
                            variable to create the runtime packages.
                            </para></listitem>
                    </itemizedlist>
                </para>

                <para>
                    BitBake, which the OpenEmbedded build system uses, supports
                    specifying versioned dependencies.
                    Although the syntax varies depending on the packaging
                    format, BitBake hides these differences from you.
                    Here is the general syntax to specify versions with
                    the <filename>RDEPENDS</filename> variable:
                    <literallayout class='monospaced'>
     RDEPENDS_${PN} = "<replaceable>package</replaceable> (<replaceable>operator</replaceable> <replaceable>version</replaceable>)"
                    </literallayout>
                    For <filename>operator</filename>, you can specify the
                    following:
                    <literallayout class='monospaced'>
     =
     &lt;
     &gt;
     &lt;=
     &gt;=
                    </literallayout>
                    For example, the following sets up a dependency on version
                    1.2 or greater of the package <filename>foo</filename>:
                    <literallayout class='monospaced'>
     RDEPENDS_${PN} = "foo (>= 1.2)"
                    </literallayout>
                </para>

                <para>
                    For information on build-time dependencies, see the
                    <link linkend='var-DEPENDS'><filename>DEPENDS</filename></link>
                    variable.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-REQUIRED_DISTRO_FEATURES'><glossterm>REQUIRED_DISTRO_FEATURES</glossterm>
            <glossdef>
                <para>
                    When inheriting the
                    <link linkend='ref-classes-distro_features_check'><filename>distro_features_check</filename></link>
                    class, this
                    variable identifies distribution features that must
                    exist in the current configuration in order for the
                    OpenEmbedded build system to build the recipe.
                    In other words, if the
                    <filename>REQUIRED_DISTRO_FEATURES</filename> variable
                    lists a feature that does not appear in
                    <filename>DISTRO_FEATURES</filename> within the
                    current configuration, an error occurs and the
                    build stops.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-RM_OLD_IMAGE'><glossterm>RM_OLD_IMAGE</glossterm>
            <glossdef>
                <para>
                    Reclaims disk space by removing previously built
                    versions of the same image from the
                    <filename>images</filename> directory pointed to by the
                    <link linkend='var-DEPLOY_DIR'><filename>DEPLOY_DIR</filename></link>
                    variable.
                </para>

                <para>
                    Set this variable to "1" in your
                    <filename>local.conf</filename> file to remove these
                    images.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-RM_WORK_EXCLUDE'><glossterm>RM_WORK_EXCLUDE</glossterm>
            <glossdef>
                <para>
                    With <filename>rm_work</filename> enabled, this
                    variable specifies a list of recipes whose work directories
                    should not be removed.
                    See the "<link linkend='ref-classes-rm-work'><filename>rm_work.bbclass</filename></link>"
                    section for more details.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-ROOT_HOME'><glossterm>ROOT_HOME</glossterm>
            <glossdef>
                <para>
                    Defines the root home directory.
                    By default, this directory is set as follows in the
                    BitBake configuration file:
                    <literallayout class='monospaced'>
     ROOT_HOME ??= "/home/root"
                    </literallayout>
                    <note>
                        This default value is likely used because some
                        embedded solutions prefer to have a read-only root
                        filesystem and prefer to keep writeable data in one
                        place.
                    </note>
                </para>

                <para>
                    You can override the default by setting the variable
                    in any layer or in the <filename>local.conf</filename> file.
                    Because the default is set using a "weak" assignment
                    (i.e. "??="), you can use either of the following forms
                    to define your override:
                    <literallayout class='monospaced'>
     ROOT_HOME = "/root"
     ROOT_HOME ?= "/root"
                    </literallayout>
                    These override examples use <filename>/root</filename>,
                    which is probably the most commonly used override.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-ROOTFS'><glossterm>ROOTFS</glossterm>
            <glossdef>
                <para>
                    Indicates a filesystem image to include as the root
                    filesystem.
                </para>

                <para>
                    The <filename>ROOTFS</filename> variable is an optional
                    variable used with the
                    <link linkend='ref-classes-bootimg'><filename>bootimg</filename></link>
                    class.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-ROOTFS_POSTPROCESS_COMMAND'><glossterm>ROOTFS_POSTPROCESS_COMMAND</glossterm>
            <glossdef>
                <para>
                    Added by classes to run post processing commands once the
                    OpenEmbedded build system has created the root filesystem.
                    You can specify shell commands separated by semicolons:
                    <literallayout class='monospaced'>
     ROOTFS_POSTPROCESS_COMMAND += "<replaceable>shell_command</replaceable>; ... "
                    </literallayout>
                    If you need to pass the path to the root filesystem within
                    the command, you can use
                    <filename>${IMAGE_ROOTFS}</filename>, which points to
                    the root filesystem image.
                    See the
                    <link linkend='var-IMAGE_ROOTFS'><filename>IMAGE_ROOTFS</filename></link>
                    variable for more information.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-RPROVIDES'><glossterm>RPROVIDES</glossterm>
            <glossdef>
                <para>
                    A list of package name aliases that a package also provides.
                    These aliases are useful for satisfying runtime dependencies
                    of other packages both during the build and on the target
                    (as specified by
                    <filename><link linkend='var-RDEPENDS'>RDEPENDS</link></filename>).
                    <note>
                        A package's own name is implicitly already in its
                        <filename>RPROVIDES</filename> list.
                    </note>
                </para>
                <para>
                   As with all package-controlling variables, you must always
                   use the variable in conjunction with a package name override.
                   Here is an example:
                   <literallayout class='monospaced'>
     RPROVIDES_${PN} = "widget-abi-2"
                   </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-RRECOMMENDS'><glossterm>RRECOMMENDS</glossterm>
            <glossdef>
                <para>
                    A list of packages that extends the usability of a package
                    being built.
                    The package being built does not depend on this list of
                    packages in order to successfully build, but rather
                    uses them for extended usability.
                    To specify runtime dependencies for packages, see the
                    <filename><link linkend='var-RDEPENDS'>RDEPENDS</link></filename>
                    variable.
                </para>

                <para>
                    The package manager will automatically install the
                    <filename>RRECOMMENDS</filename> list of packages when
                    installing the built package.
                    However, you can prevent listed packages from being
                    installed by using the
                    <link linkend='var-BAD_RECOMMENDATIONS'><filename>BAD_RECOMMENDATIONS</filename></link>,
                    <link linkend='var-NO_RECOMMENDATIONS'><filename>NO_RECOMMENDATIONS</filename></link>,
                    and
                    <link linkend='var-PACKAGE_EXCLUDE'><filename>PACKAGE_EXCLUDE</filename></link>
                    variables.
                </para>

                <para>
                    Packages specified in
                    <filename>RRECOMMENDS</filename> need not actually be
                    produced.
                    However, a recipe must exist that provides each package,
                    either through the
                    <link linkend='var-PACKAGES'><filename>PACKAGES</filename></link>
                    or
                    <link linkend='var-PACKAGES_DYNAMIC'><filename>PACKAGES_DYNAMIC</filename></link>
                    variables or the
                    <link linkend='var-RPROVIDES'><filename>RPROVIDES</filename></link>
                    variable, or an error will occur during the build.
                    If such a recipe does exist and the package is not produced,
                    the build continues without error.
                </para>

                <para>
                    Because the <filename>RRECOMMENDS</filename> variable
                    applies to packages being built, you should always attach
                    an override to the variable to specify the particular
                    package whose usability is being extended.
                    For example, suppose you are building a development package
                    that is extended to support wireless functionality.
                    In this case, you would use the following:
                    <literallayout class='monospaced'>
     RRECOMMENDS_${PN}-dev += "<replaceable>wireless_package_name</replaceable>"
                    </literallayout>
                    In the example, the package name
                    (<filename>${<link linkend='var-PN'>PN</link>}-dev</filename>)
                    must appear as it would in the
                    <filename><link linkend='var-PACKAGES'>PACKAGES</link></filename>
                    namespace before any renaming of the output package by
                    classes such as <filename>debian.bbclass</filename>.
                </para>

                <para>
                    BitBake, which the OpenEmbedded build system uses, supports
                    specifying versioned recommends.
                    Although the syntax varies depending on the packaging
                    format, BitBake hides these differences from you.
                    Here is the general syntax to specify versions with
                    the <filename>RRECOMMENDS</filename> variable:
                    <literallayout class='monospaced'>
     RRECOMMENDS_${PN} = "<replaceable>package</replaceable> (<replaceable>operator</replaceable> <replaceable>version</replaceable>)"
                    </literallayout>
                    For <filename>operator</filename>, you can specify the
                    following:
                    <literallayout class='monospaced'>
     =
     &lt;
     &gt;
     &lt;=
     &gt;=
                    </literallayout>
                    For example, the following sets up a recommend on version
                    1.2 or greater of the package <filename>foo</filename>:
                    <literallayout class='monospaced'>
     RRECOMMENDS_${PN} = "foo (>= 1.2)"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-RREPLACES'><glossterm>RREPLACES</glossterm>
            <glossdef>
                <para>
                    A list of packages replaced by a package.
                    The package manager uses this variable to determine which
                    package should be installed to replace other package(s)
                    during an upgrade.
                    In order to also have the other package(s) removed at the
                    same time, you must add the name of the other
                    package to the
                    <filename><link linkend='var-RCONFLICTS'>RCONFLICTS</link></filename> variable.
                </para>
                <para>
                   As with all package-controlling variables, you must use
                   this variable in conjunction with a package name
                   override.
                   Here is an example:
                   <literallayout class='monospaced'>
     RREPLACES_${PN} = "<replaceable>other-package-being-replaced</replaceable>"
                   </literallayout>
                </para>

                <para>
                    BitBake, which the OpenEmbedded build system uses, supports
                    specifying versioned replacements.
                    Although the syntax varies depending on the packaging
                    format, BitBake hides these differences from you.
                    Here is the general syntax to specify versions with
                    the <filename>RREPLACES</filename> variable:
                    <literallayout class='monospaced'>
     RREPLACES_${PN} = "<replaceable>package</replaceable> (<replaceable>operator</replaceable> <replaceable>version</replaceable>)"
                    </literallayout>
                    For <filename>operator</filename>, you can specify the
                    following:
                    <literallayout class='monospaced'>
     =
     &lt;
     &gt;
     &lt;=
     &gt;=
                    </literallayout>
                    For example, the following sets up a replacement using
                    version 1.2 or greater of the package
                    <filename>foo</filename>:
                    <literallayout class='monospaced'>
     RREPLACES_${PN} = "foo (>= 1.2)"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-RSUGGESTS'><glossterm>RSUGGESTS</glossterm>
            <glossdef>
                <para>
                    A list of additional packages that you can suggest for
                    installation by the package manager at the time a package
                    is installed.
                    Not all package managers support this functionality.
                </para>
                <para>
                   As with all package-controlling variables, you must always
                   use this variable in conjunction with a package name
                   override.
                   Here is an example:
                   <literallayout class='monospaced'>
     RSUGGESTS_${PN} = "<replaceable>useful-package</replaceable> <replaceable>another-package</replaceable>"
                   </literallayout>
                </para>
            </glossdef>
        </glossentry>

    </glossdiv>

    <glossdiv id='var-glossary-s'><title>S</title>

        <glossentry id='var-S'><glossterm>S</glossterm>
            <glossdef>
                <para>
                    The location in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>
                    where unpacked recipe source code resides.
                    This location is within the work directory
                    (<filename><link linkend='var-WORKDIR'>WORKDIR</link></filename>),
                    which is not static.
                    The unpacked source location depends on the recipe name
                    (<filename><link linkend='var-PN'>PN</link></filename>) and
                    recipe version
                    (<filename><link linkend='var-PV'>PV</link></filename>) as
                    follows:
                    <literallayout class='monospaced'>
     ${WORKDIR}/${PN}-${PV}
                    </literallayout>
                    As an example, assume a
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>
                    top-level folder named <filename>poky</filename> and a
                    default Build Directory at <filename>poky/build</filename>.
                    In this case, the work directory the build system uses
                    to keep the unpacked recipe for <filename>db</filename>
                    is the following:
                    <literallayout class='monospaced'>
     poky/build/tmp/work/qemux86-poky-linux/db/5.1.19-r3/db-5.1.19
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SANITY_REQUIRED_UTILITIES'><glossterm>SANITY_REQUIRED_UTILITIES</glossterm>
            <glossdef>
                <para>
                    Specifies a list of command-line utilities that should be
                    checked for during the initial sanity checking process when
                    running BitBake.
                    If any of the utilities are not installed on the build host,
                    then BitBake immediately exits with an error.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SANITY_TESTED_DISTROS'><glossterm>SANITY_TESTED_DISTROS</glossterm>
            <glossdef>
                <para>
                    A list of the host distribution identifiers that the
                    build system has been tested against.
                    Identifiers consist of the host distributor ID
                    followed by the release,
                    as reported by the <filename>lsb_release</filename> tool
                    or as read from <filename>/etc/lsb-release</filename>.
                    Separate the list items with explicit newline
                    characters (<filename>\n</filename>).
                    If <filename>SANITY_TESTED_DISTROS</filename> is not empty
                    and the current value of
                    <link linkend='var-NATIVELSBSTRING'><filename>NATIVELSBSTRING</filename></link>
                    does not appear in the list, then the build system reports
                    a warning that indicates the current host distribution has
                    not been tested as a build host.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SDK_ARCH'><glossterm>SDK_ARCH</glossterm>
            <glossdef>
                <para>
                    The target architecture for the SDK.
                    Typically, you do not directly set this variable.
                    Instead, use
                    <link linkend='var-SDKMACHINE'><filename>SDKMACHINE</filename></link>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SDK_DEPLOY'><glossterm>SDK_DEPLOY</glossterm>
            <glossdef>
                <para>
                    The directory set up and used by the
                    <link linkend='ref-classes-populate-sdk'><filename>populate_sdk_base</filename></link>
                    to which the SDK is deployed.
                    The <filename>populate_sdk_base</filename> class defines
                    <filename>SDK_DEPLOY</filename> as follows:
                    <literallayout class='monospaced'>
     SDK_DEPLOY = "${<link linkend='var-TMPDIR'>TMPDIR</link>}/deploy/sdk"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SDK_DIR'><glossterm>SDK_DIR</glossterm>
            <glossdef>
                <para>
                    The parent directory used by the OpenEmbedded build system
                    when creating SDK output.
                    The
                    <link linkend='ref-classes-populate-sdk-*'><filename>populate_sdk_base</filename></link>
                    class defines the variable as follows:
                    <literallayout class='monospaced'>
     SDK_DIR = "${<link linkend='var-WORKDIR'><filename>WORKDIR</filename></link>}/sdk"
                    </literallayout>
                    <note>
                        The <filename>SDK_DIR</filename> directory is a
                        temporary directory as it is part of
                        <filename>WORKDIR</filename>.
                        The final output directory is
                        <link linkend='var-SDK_DEPLOY'><filename>SDK_DEPLOY</filename></link>.
                    </note>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SDK_NAME'><glossterm>SDK_NAME</glossterm>
            <glossdef>
                <para>
                    The base name for SDK output files.
                    The name is derived from the
                    <link linkend='var-DISTRO'><filename>DISTRO</filename></link>,
                    <link linkend='var-TCLIBC'><filename>TCLIBC</filename></link>,
                    <link linkend='var-SDK_ARCH'><filename>SDK_ARCH</filename></link>,
                    <link linkend='var-IMAGE_BASENAME'><filename>IMAGE_BASENAME</filename></link>,
                    and
                    <link linkend='var-TUNE_PKGARCH'><filename>TUNE_PKGARCH</filename></link>
                    variables:
                    <literallayout class='monospaced'>
     SDK_NAME = "${DISTRO}-${TCLIBC}-${SDK_ARCH}-${IMAGE_BASENAME}-${TUNE_PKGARCH}"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SDK_OUTPUT'><glossterm>SDK_OUTPUT</glossterm>
            <glossdef>
                <para>
                    The location used by the OpenEmbedded build system when
                    creating SDK output.
                    The
                    <link linkend='ref-classes-populate-sdk-*'><filename>populate_sdk_base</filename></link>
                    class defines the variable as follows:
                    <literallayout class='monospaced'>
     SDK_OUTPUT = "${<link linkend='var-SDK_DIR'>SDK_DIR</link>}/image"
                    </literallayout>
                    <note>
                        The <filename>SDK_OUTPUT</filename> directory is a
                        temporary directory as it is part of
                        <filename>WORKDIR</filename> by way of
                        <filename>SDK_DIR</filename>.
                        The final output directory is
                        <link linkend='var-SDK_DEPLOY'><filename>SDK_DEPLOY</filename></link>.
                    </note>

                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SDK_PACKAGE_ARCHS'><glossterm>SDK_PACKAGE_ARCHS</glossterm>
            <glossdef>
                <para>
                    Specifies a list of architectures compatible with
                    the SDK machine.
                    This variable is set automatically and should not
                    normally be hand-edited.
                    Entries are separated using spaces and listed in order
                    of priority.
                    The default value for
                    <filename>SDK_PACKAGE_ARCHS</filename> is "all any noarch
                    ${SDK_ARCH}-${SDKPKGSUFFIX}".
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SDKIMAGE_FEATURES'><glossterm>SDKIMAGE_FEATURES</glossterm>
            <glossdef>
                <para>Equivalent to
                    <filename><link linkend='var-IMAGE_FEATURES'>IMAGE_FEATURES</link></filename>.
                    However, this variable applies to the SDK generated from an
                    image using the following command:
                    <literallayout class='monospaced'>
     $ bitbake -c populate_sdk <replaceable>imagename</replaceable>
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SDKMACHINE'><glossterm>SDKMACHINE</glossterm>
            <glossdef>
                <para>
                    The machine for which the Application Development Toolkit
                    (ADT) or SDK is built.
                    In other words, the SDK or ADT is built such that it
                    runs on the target you specify with the
                    <filename>SDKMACHINE</filename> value.
                    The value points to a corresponding
                    <filename>.conf</filename> file under
                    <filename>conf/machine-sdk/</filename>.
                </para>

                <para>
                     You can use "i686" and "x86_64" as possible values
                     for this variable. The variable defaults to "i686"
                     and is set in the local.conf file in the Build Directory.
                     <literallayout class='monospaced'>
     SDKMACHINE ?= "i686"
                     </literallayout>
                     <note>
                         You cannot set the <filename>SDKMACHINE</filename>
                         variable in your distribution configuration file.
                         If you do, the configuration will not take affect.
                     </note>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SDKPATH'><glossterm>SDKPATH</glossterm>
            <glossdef>
                <para>
                    Defines the path offered to the user for installation
                    of the SDK that is generated by the OpenEmbedded build
                    system.
                    The path appears as the default location for installing
                    the SDK when you run the SDK's installation script.
                    You can override the offered path when you run the
                    script.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SECTION'><glossterm>SECTION</glossterm>
            <glossdef>
                <para>The section in which packages should be categorized.
                    Package management utilities can make use of this variable.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SELECTED_OPTIMIZATION'><glossterm>SELECTED_OPTIMIZATION</glossterm>
            <glossdef>
                <para>
                    Specifies the optimization flags passed to the C compiler
                    when building for the target.
                    The flags are passed through the default value of the
                    <link linkend='var-TARGET_CFLAGS'><filename>TARGET_CFLAGS</filename></link>
                    variable.
                </para>

                <para>
                    The <filename>SELECTED_OPTIMIZATION</filename> variable
                    takes the value of
                    <filename><link linkend='var-FULL_OPTIMIZATION'>FULL_OPTIMIZATION</link></filename>
                    unless <filename><link linkend='var-DEBUG_BUILD'>DEBUG_BUILD</link></filename> = "1".
                    If that is the case, the value of
                    <filename><link linkend='var-DEBUG_OPTIMIZATION'>DEBUG_OPTIMIZATION</link></filename> is used.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SERIAL_CONSOLE'><glossterm>SERIAL_CONSOLE</glossterm>
            <glossdef>
                <para>
                    Defines a serial console (TTY) to enable using getty.
                    Provide a value that specifies the baud rate followed by
                    the TTY device name separated by a space.
                    You cannot specify more than one TTY device:
                    <literallayout class='monospaced'>
     SERIAL_CONSOLE = "115200 ttyS0"
                    </literallayout>
                    <note>
                        The <filename>SERIAL_CONSOLE</filename> variable
                        is deprecated.
                        Please use the
                        <link linkend='var-SERIAL_CONSOLES'><filename>SERIAL_CONSOLES</filename></link>
                        variable.
                    </note>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SERIAL_CONSOLES'><glossterm>SERIAL_CONSOLES</glossterm>
            <glossdef>
                <para>
                    Defines the serial consoles (TTYs) to enable using getty.
                    Provide a value that specifies the baud rate followed by
                    the TTY device name separated by a semicolon.
                    Use spaces to separate multiple devices:
                    <literallayout class='monospaced'>
     SERIAL_CONSOLES = "115200;ttyS0 115200;ttyS1"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SERIAL_CONSOLES_CHECK'><glossterm>SERIAL_CONSOLES_CHECK</glossterm>
            <glossdef>
                <para>
                    Similar to
                    <link linkend='var-SERIAL_CONSOLES'><filename>SERIAL_CONSOLES</filename></link>
                    except the device is checked for existence before attempting
                    to enable it.
                    This variable is currently only supported with SysVinit
                    (i.e. not with systemd).
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SIGGEN_EXCLUDE_SAFE_RECIPE_DEPS'><glossterm>SIGGEN_EXCLUDE_SAFE_RECIPE_DEPS</glossterm>
            <glossdef>
                <para>
                    A list of recipe dependencies that should not be used to
                    determine signatures of tasks from one recipe when they
                    depend on tasks from another recipe.
                    For example:
                    <literallayout class='monospaced'>
    SIGGEN_EXCLUDE_SAFE_RECIPE_DEPS += "intone->mplayer2"
                    </literallayout>
                    In this example, <filename>intone</filename> depends on
                    <filename>mplayer2</filename>.
                </para>

                <para>
                    Use of this variable is one mechanism to remove dependencies
                    that affect task signatures and thus force rebuilds when a
                    recipe changes.
                    <note><title>Caution</title>
                        If you add an inappropriate dependency for a recipe
                        relationship, the software might break during
                        runtime if the interface of the second recipe was
                        changed after the first recipe had been built.
                    </note>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SIGGEN_EXCLUDERECIPES_ABISAFE'><glossterm>SIGGEN_EXCLUDERECIPES_ABISAFE</glossterm>
            <glossdef>
                <para>
                    A list of recipes that are completely stable and will
                    never change.
                    The ABI for the recipes in the list are presented by
                    output from the tasks run to build the recipe.
                    Use of this variable is one way to remove dependencies from
                    one recipe on another that affect task signatures and
                    thus force rebuilds when the recipe changes.
                    <note><title>Caution</title>
                        If you add an inappropriate variable to this list,
                        the software might break at runtime if the
                        interface of the recipe was changed after the other
                        had been built.
                    </note>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SITEINFO_BITS'><glossterm>SITEINFO_BITS</glossterm>
            <glossdef>
                <para>
                    Specifies the number of bits for the target system CPU.
                    The value should be either "32" or "64".
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SITEINFO_ENDIANNESS'><glossterm>SITEINFO_ENDIANNESS</glossterm>
            <glossdef>
                <para>
                    Specifies the endian byte order of the target system.
                    The value should be either "le" for little-endian or "be" for big-endian.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SOC_FAMILY'><glossterm>SOC_FAMILY</glossterm>
            <glossdef>
                <para>
                    Groups together machines based upon the same family
                    of SOC (System On Chip).
                    You typically set this variable in a common
                    <filename>.inc</filename> file that you include in the
                    configuration files of all the machines.
                    <note>
                        You must include
                        <filename>conf/machine/include/soc-family.inc</filename>
                        for this variable to appear in
                    <link linkend='var-MACHINEOVERRIDES'><filename>MACHINEOVERRIDES</filename></link>.
                    </note>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SOLIBS'><glossterm>SOLIBS</glossterm>
            <glossdef>
                <para>
                    Defines the suffix for shared libraries used on the
                    target platform.
                    By default, this suffix is ".so.*" for all Linux-based
                    systems and is defined in the
                    <filename>meta/conf/bitbake.conf</filename> configuration
                    file.
                </para>

                <para>
                    You will see this variable referenced in the default values
                    of <filename>FILES_${PN}</filename>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SOLIBSDEV'><glossterm>SOLIBSDEV</glossterm>
            <glossdef>
                <para>
                    Defines the suffix for the development symbolic link
                    (symlink) for shared libraries on the target platform.
                    By default, this suffix is ".so" for Linux-based
                    systems and is defined in the
                    <filename>meta/conf/bitbake.conf</filename> configuration
                    file.
                </para>

                <para>
                    You will see this variable referenced in the default values
                    of <filename>FILES_${PN}-dev</filename>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SOURCE_MIRROR_URL'><glossterm>SOURCE_MIRROR_URL</glossterm>
            <glossdef>
                <para>
                    Defines your own
                    <link linkend='var-PREMIRRORS'><filename>PREMIRRORS</filename></link>
                    from which to first fetch source before attempting to fetch
                    from the upstream specified in
                    <link linkend='var-SRC_URI'><filename>SRC_URI</filename></link>.
                </para>

                <para>
                    To use this variable, you must globally inherit the
                    <link linkend='ref-classes-own-mirrors'><filename>own-mirrors</filename></link>
                    class and then provide the URL to your mirrors.
                    Here is an example:
                    <literallayout class='monospaced'>
     INHERIT += "own-mirrors"
     SOURCE_MIRROR_URL = "http://example.com/my-source-mirror"
                    </literallayout>
                    <note>
                        You can specify only a single URL in
                        <filename>SOURCE_MIRROR_URL</filename>.
                    </note>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SPDXLICENSEMAP'><glossterm>SPDXLICENSEMAP</glossterm>
            <glossdef>
                <para>
                    Maps commonly used license names to their SPDX counterparts
                    found in <filename>meta/files/common-licenses/</filename>.
                    For the default <filename>SPDXLICENSEMAP</filename>
                    mappings, see the
                    <filename>meta/conf/licenses.conf</filename> file.
                </para>

                <para>
                    For additional information, see the
                    <link linkend='var-LICENSE'><filename>LICENSE</filename></link>
                    variable.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SPECIAL_PKGSUFFIX'><glossterm>SPECIAL_PKGSUFFIX</glossterm>
            <glossdef>
                <para>
                    A list of prefixes for <link linkend='var-PN'><filename>PN</filename></link> used by the
                    OpenEmbedded build system to create variants of recipes or packages.
                    The list specifies the prefixes to strip off during certain circumstances
                    such as the generation of the <link linkend='var-BPN'><filename>BPN</filename></link> variable.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SRC_URI'><glossterm>SRC_URI</glossterm>
            <glossdef>
                <para>The list of source files - local or remote.
                    This variable tells the OpenEmbedded build system which bits
                    to pull in for the build and how to pull them in.
                    For example, if the recipe or append file only needs to
                    fetch a tarball from the Internet, the recipe or
                    append file uses a single <filename>SRC_URI</filename>
                    entry.
                    On the other hand, if the recipe or append file needs to
                    fetch a tarball, apply two patches, and include a custom
                    file, the recipe or append file would include four
                    instances of the variable.</para>
                <para>The following list explains the available URI protocols:
                    <itemizedlist>
                        <listitem><para><emphasis><filename>file://</filename> -</emphasis>
                            Fetches files, which are usually files shipped with
                            the
                            <ulink url='&YOCTO_DOCS_DEV_URL;#metadata'>Metadata</ulink>,
                            from the local machine.
                            The path is relative to the
                            <link linkend='var-FILESPATH'><filename>FILESPATH</filename></link>
                            variable.
                            Thus, the build system searches, in order, from the
                            following directories, which are assumed to be a
                            subdirectories of the directory in which the
                            recipe file (<filename>.bb</filename>) or
                            append file (<filename>.bbappend</filename>)
                            resides:
                            <itemizedlist>
                                <listitem><para><emphasis><filename>${BPN}</filename> -</emphasis>
                                    The base recipe name without any special
                                    suffix or version numbers.
                                    </para></listitem>
                                <listitem><para><emphasis><filename>${BP}</filename> -</emphasis>
                                    <filename>${<link linkend='var-BPN'>BPN</link>}-${PV}</filename>.
                                    The base recipe name and version but without
                                    any special package name suffix.
                                    </para></listitem>
                                <listitem><para><emphasis>files -</emphasis>
                                    Files within a directory, which is named
                                    <filename>files</filename> and is also
                                    alongside the recipe or append file.
                                    </para></listitem>
                            </itemizedlist>
                            <note>
                                If you want the build system to pick up files
                                specified through a
                                <filename>SRC_URI</filename>
                                statement from your append file, you need to be
                                sure to extend the
                                <filename>FILESPATH</filename>
                                variable by also using the
                                <link linkend='var-FILESEXTRAPATHS'><filename>FILESEXTRAPATHS</filename></link>
                                variable from within your append file.
                            </note>
                            </para></listitem>
                        <listitem><para><emphasis><filename>bzr://</filename> -</emphasis> Fetches files from a
                            Bazaar revision control repository.</para></listitem>
                        <listitem><para><emphasis><filename>git://</filename> -</emphasis> Fetches files from a
                            Git revision control repository.</para></listitem>
                        <listitem><para><emphasis><filename>osc://</filename> -</emphasis> Fetches files from
                            an OSC (OpenSUSE Build service) revision control repository.</para></listitem>
                        <listitem><para><emphasis><filename>repo://</filename> -</emphasis> Fetches files from
                            a repo (Git) repository.</para></listitem>
                        <listitem><para><emphasis><filename>ccrc://</filename> -</emphasis>
                            Fetches files from a ClearCase repository.
                            </para></listitem>
                        <listitem><para><emphasis><filename>http://</filename> -</emphasis> Fetches files from
                            the Internet using <filename>http</filename>.</para></listitem>
                        <listitem><para><emphasis><filename>https://</filename> -</emphasis> Fetches files
                            from the Internet using <filename>https</filename>.</para></listitem>
                        <listitem><para><emphasis><filename>ftp://</filename> -</emphasis> Fetches files
                            from the Internet using <filename>ftp</filename>.</para></listitem>
                        <listitem><para><emphasis><filename>cvs://</filename> -</emphasis> Fetches files from
                            a CVS revision control repository.</para></listitem>
                        <listitem><para><emphasis><filename>hg://</filename> -</emphasis> Fetches files from
                            a Mercurial (<filename>hg</filename>) revision control repository.</para></listitem>
                        <listitem><para><emphasis><filename>p4://</filename> -</emphasis> Fetches files from
                            a Perforce (<filename>p4</filename>) revision control repository.</para></listitem>
                        <listitem><para><emphasis><filename>ssh://</filename> -</emphasis> Fetches files from
                            a secure shell.</para></listitem>
                        <listitem><para><emphasis><filename>svn://</filename> -</emphasis> Fetches files from
                            a Subversion (<filename>svn</filename>) revision control repository.</para></listitem>
                    </itemizedlist>
                </para>
                <para>Standard and recipe-specific options for <filename>SRC_URI</filename> exist.
                    Here are standard options:
                    <itemizedlist>
                        <listitem><para><emphasis><filename>apply</filename> -</emphasis> Whether to apply
                            the patch or not.
                            The default action is to apply the patch.</para></listitem>
                        <listitem><para><emphasis><filename>striplevel</filename> -</emphasis> Which
                            striplevel to use when applying the patch.
                            The default level is 1.</para></listitem>
                        <listitem><para><emphasis><filename>patchdir</filename> -</emphasis> Specifies
                            the directory in which the patch should be applied.
                            The default is <filename>${</filename><link linkend='var-S'><filename>S</filename></link><filename>}</filename>.
                            </para></listitem>
                    </itemizedlist>
                </para>
                <para>Here are options specific to recipes building code from a revision control system:
                    <itemizedlist>
                        <listitem><para><emphasis><filename>mindate</filename> -</emphasis>
                            Apply the patch only if
                            <link linkend='var-SRCDATE'><filename>SRCDATE</filename></link>
                            is equal to or greater than <filename>mindate</filename>.
                            </para></listitem>
                        <listitem><para><emphasis><filename>maxdate</filename> -</emphasis>
                            Apply the patch only if <filename>SRCDATE</filename>
                            is not later than <filename>mindate</filename>.
                            </para></listitem>
                        <listitem><para><emphasis><filename>minrev</filename> -</emphasis>
                            Apply the patch only if <filename>SRCREV</filename>
                            is equal to or greater than <filename>minrev</filename>.
                            </para></listitem>
                        <listitem><para><emphasis><filename>maxrev</filename> -</emphasis>
                            Apply the patch only if <filename>SRCREV</filename>
                            is not later than <filename>maxrev</filename>.
                            </para></listitem>
                        <listitem><para><emphasis><filename>rev</filename> -</emphasis>
                            Apply the patch only if <filename>SRCREV</filename>
                            is equal to <filename>rev</filename>.
                            </para></listitem>
                        <listitem><para><emphasis><filename>notrev</filename> -</emphasis>
                            Apply the patch only if <filename>SRCREV</filename>
                            is not equal to <filename>rev</filename>.
                            </para></listitem>
                    </itemizedlist>
                </para>
                <para>Here are some additional options worth mentioning:
                    <itemizedlist>
                        <listitem><para><emphasis><filename>unpack</filename> -</emphasis> Controls
                            whether or not to unpack the file if it is an archive.
                            The default action is to unpack the file.</para></listitem>
                        <listitem><para><emphasis><filename>subdir</filename> -</emphasis> Places the file
                            (or extracts its contents) into the specified
                            subdirectory of <link linkend='var-WORKDIR'><filename>WORKDIR</filename></link>.
                            This option is useful for unusual tarballs or other archives that
                            do not have their files already in a subdirectory within the archive.
                            </para></listitem>
                        <listitem><para><emphasis><filename>name</filename> -</emphasis> Specifies a
                            name to be used for association with <filename>SRC_URI</filename> checksums
                            when you have more than one file specified in <filename>SRC_URI</filename>.
                            </para></listitem>
                        <listitem><para><emphasis><filename>downloadfilename</filename> -</emphasis> Specifies
                            the filename used when storing the downloaded file.</para></listitem>
                    </itemizedlist>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SRC_URI_OVERRIDES_PACKAGE_ARCH'><glossterm>SRC_URI_OVERRIDES_PACKAGE_ARCH</glossterm>
            <glossdef>
                <para>
                    By default, the OpenEmbedded build system automatically detects whether
                    <filename><link linkend='var-SRC_URI'>SRC_URI</link></filename>
                    contains files that are machine-specific.
                    If so, the build system automatically changes
                    <filename><link linkend='var-PACKAGE_ARCH'>PACKAGE_ARCH</link></filename>.
                    Setting this variable to "0" disables this behavior.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SRCDATE'><glossterm>SRCDATE</glossterm>
            <glossdef>
                <para>
                    The date of the source code used to build the package.
                    This variable applies only if the source was fetched from a Source Code Manager (SCM).
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SRCPV'><glossterm>SRCPV</glossterm>
            <glossdef>
                <para>
                    Returns the version string of the current package.
                    This string is used to help define the value of
                    <link linkend='var-PV'><filename>PV</filename></link>.
                </para>

                <para>
                    The <filename>SRCPV</filename> variable is defined in the
                    <filename>meta/conf/bitbake.conf</filename> configuration
                    file in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>
                    as follows:
                    <literallayout class='monospaced'>
     SRCPV = "${@bb.fetch2.get_srcrev(d)}"
                    </literallayout>
                </para>

                <para>
                    Recipes that need to define <filename>PV</filename> do so
                    with the help of the <filename>SRCPV</filename>.
                    For example, the <filename>ofono</filename> recipe
                    (<filename>ofono_git.bb</filename>) located in
                    <filename>meta/recipes-connectivity</filename> in the
                    Source Directory defines <filename>PV</filename> as
                    follows:
                    <literallayout class='monospaced'>
     PV = "0.12-git${SRCPV}"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SRCREV'><glossterm>SRCREV</glossterm>
            <glossdef>
                <para>
                    The revision of the source code used to build the package.
                    This variable applies to Subversion, Git, Mercurial and Bazaar
                    only.
                    Note that if you wish to build a fixed revision and you wish
                    to avoid performing a query on the remote repository every time
                    BitBake parses your recipe, you should specify a <filename>SRCREV</filename> that is a
                    full revision identifier and not just a tag.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SSTATE_DIR'><glossterm>SSTATE_DIR</glossterm>
            <glossdef>
                <para>The directory for the shared state cache.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SSTATE_MIRROR_ALLOW_NETWORK'><glossterm>SSTATE_MIRROR_ALLOW_NETWORK</glossterm>
            <glossdef>
                <para>
                    If set to "1", allows fetches from
                    mirrors that are specified in
                    <link linkend='var-SSTATE_MIRRORS'><filename>SSTATE_MIRRORS</filename></link>
                    to work even when fetching from the network has been
                    disabled by setting <filename>BB_NO_NETWORK</filename>
                    to "1".
                    Using the
                    <filename>SSTATE_MIRROR_ALLOW_NETWORK</filename>
                    variable is useful if you have set
                    <filename>SSTATE_MIRRORS</filename> to point to an
                    internal server for your shared state cache, but
                    you want to disable any other fetching from the network.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SSTATE_MIRRORS'><glossterm>SSTATE_MIRRORS</glossterm>
            <glossdef>
                <para>
                    Configures the OpenEmbedded build system to search other
                    mirror locations for prebuilt cache data objects before
                    building out the data.
                    This variable works like fetcher
                    <link linkend='var-MIRRORS'><filename>MIRRORS</filename></link>
                    and <link linkend='var-PREMIRRORS'><filename>PREMIRRORS</filename></link>
                    and points to the cache locations to check for the shared
                    objects.
                </para>

                <para>
                    You can specify a filesystem directory or a remote URL such
                    as HTTP or FTP.
                    The locations you specify need to contain the shared state
                    cache (sstate-cache) results from previous builds.
                    The sstate-cache you point to can also be from builds on
                    other machines.
                </para>

                <para>
                    If a mirror uses the same structure as
                    <link linkend='var-SSTATE_DIR'><filename>SSTATE_DIR</filename></link>,
                    you need to add
                    "PATH" at the end as shown in the examples below.
                    The build system substitutes the correct path within the
                    directory structure.
                    <literallayout class='monospaced'>
     SSTATE_MIRRORS ?= "\
     file://.* http://<replaceable>someserver</replaceable>.tld/share/sstate/PATH \n \
     file://.* file:///<replaceable>some-local-dir</replaceable>/sstate/PATH"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-STAGING_BASE_LIBDIR_NATIVE'><glossterm>STAGING_BASE_LIBDIR_NATIVE</glossterm>
            <glossdef>
                <para>
                    Specifies the path to the <filename>/lib</filename>
                    subdirectory of the sysroot directory for the
                    build host.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-STAGING_BASELIBDIR'><glossterm>STAGING_BASELIBDIR</glossterm>
            <glossdef>
                <para>
                    Specifies the path to the <filename>/lib</filename>
                    subdirectory of the sysroot directory for the target
                    for which the current recipe is being built
                    (<link linkend='var-STAGING_DIR_HOST'><filename>STAGING_DIR_HOST</filename></link>).
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-STAGING_BINDIR'><glossterm>STAGING_BINDIR</glossterm>
            <glossdef>
                <para>
                    Specifies the path to the
                    <filename>/usr/bin</filename> subdirectory of the
                    sysroot directory for the target for which the current
                    recipe is being built
                    (<link linkend='var-STAGING_DIR_HOST'><filename>STAGING_DIR_HOST</filename></link>).
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-STAGING_BINDIR_CROSS'><glossterm>STAGING_BINDIR_CROSS</glossterm>
            <glossdef>
                <para>
                    Specifies the path to the directory containing binary
                    configuration scripts.
                    These scripts provide configuration information for
                    other software that wants to make use of libraries or
                    include files provided by the software associated with
                    the script.
                    <note>
                        This style of build configuration has been largely
                        replaced by <filename>pkg-config</filename>.
                        Consequently, if <filename>pkg-config</filename>
                        is supported by the library to which you are linking,
                        it is recommended you use
                        <filename>pkg-config</filename> instead of a
                        provided configuration script.
                    </note>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-STAGING_BINDIR_NATIVE'><glossterm>STAGING_BINDIR_NATIVE</glossterm>
            <glossdef>
                <para>
                    Specifies the path to the
                    <filename>/usr/bin</filename> subdirectory of the
                    sysroot directory for the build host.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-STAGING_DATADIR'><glossterm>STAGING_DATADIR</glossterm>
            <glossdef>
                <para>
                     Specifies the path to the <filename>/usr/share</filename>
                     subdirectory of the sysroot directory for the target
                     for which the current recipe is being built
                     (<link linkend='var-STAGING_DIR_HOST'><filename>STAGING_DIR_HOST</filename></link>).
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-STAGING_DIR'><glossterm>STAGING_DIR</glossterm>
            <glossdef>
                <para>
                    Specifies the path to the top-level sysroots directory
                    (i.e.
                    <filename>${</filename><link linkend='var-TMPDIR'><filename>TMPDIR</filename></link><filename>}/sysroots</filename>).
                    <note>
                        Recipes should never write files directly under
                        this directory because the OpenEmbedded build system
                        manages the directory automatically.
                        Instead, files should be installed to
                        <filename>${</filename><link linkend='var-D'><filename>D</filename></link><filename>}</filename>
                        within your recipe's
                        <link linkend='ref-tasks-install'><filename>do_install</filename></link>
                        task and then the OpenEmbedded build system will
                        stage a subset of those files into the sysroot.
                    </note>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-STAGING_DIR_HOST'><glossterm>STAGING_DIR_HOST</glossterm>
            <glossdef>
                <para>
                    Specifies the path to the primary sysroot directory for
                    which the target is being built.
                    Depending on the type of recipe and the build target, the
                    recipe's value is as follows:
                    <itemizedlist>
                        <listitem><para>For recipes building for the target
                           machine, the value is "${STAGING_DIR}/${MACHINE}".
                           </para></listitem>
                        <listitem><para>For <filename>native</filename>
                           recipes building
                           for the build host, the value is empty given the
                           assumption that when building for the build host,
                           the build host's own directories should be used.
                           </para></listitem>
                        <listitem><para>For <filename>nativesdk</filename>
                           recipes that Build for the SDK, the value is
                           "${STAGING_DIR}/${MULTIMACH_HOST_SYS}".
                           </para></listitem>
                    </itemizedlist>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-STAGING_DATADIR_NATIVE'><glossterm>STAGING_DATADIR_NATIVE</glossterm>
            <glossdef>
                <para>
                    Specifies the path to the <filename>/usr/share</filename>
                    subdirectory of the sysroot directory for the build host.
                </para>
            </glossdef>
        </glossentry>



        <glossentry id='var-STAGING_DIR_NATIVE'><glossterm>STAGING_DIR_NATIVE</glossterm>
            <glossdef>
                <para>
                    Specifies the path to the sysroot directory for the
                    build host.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-STAGING_DIR_TARGET'><glossterm>STAGING_DIR_TARGET</glossterm>
            <glossdef>
                <para>
                    Specifies the path to the sysroot directory for the
                    target for which the current recipe is being built.
                    In most cases, this path is the
                    <link linkend='var-STAGING_DIR_HOST'><filename>STAGING_DIR_HOST</filename></link>.
                </para>

                <para>
                    Some recipes build binaries that can run on the target
                    system but those binaries in turn generate code for
                    another different system (e.g. cross-canadian recipes).
                    Using terminology from GNU, the primary system is referred
                    to as the "HOST" and the secondary, or different, system is
                    referred to as the "TARGET".
                    Thus, the binaries run on the "HOST" system and
                    and generate binaries for the "TARGET" system.
                    <filename>STAGING_DIR_TARGET</filename> points to the
                    sysroot used for the "TARGET" system.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-STAGING_ETCDIR_NATIVE'><glossterm>STAGING_ETCDIR_NATIVE</glossterm>
            <glossdef>
                <para>
                    Specifies the path to the <filename>/etc</filename>
                    subdirectory of the sysroot directory for the
                    build host.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-STAGING_EXECPREFIXDIR'><glossterm>STAGING_EXECPREFIXDIR</glossterm>
            <glossdef>
                <para>
                    Specifies the path to the <filename>/usr</filename>
                    subdirectory of the sysroot directory for the target
                    for which the current recipe is being built
                    (<link linkend='var-STAGING_DIR_HOST'><filename>STAGING_DIR_HOST</filename></link>).
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-STAGING_INCDIR'><glossterm>STAGING_INCDIR</glossterm>
            <glossdef>
                <para>
                    Specifies the path to the
                    <filename>/usr/include</filename> subdirectory of the
                    sysroot directory for the target for which the current
                    recipe being built
                    (<link linkend='var-STAGING_DIR_HOST'><filename>STAGING_DIR_HOST</filename></link>).
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-STAGING_INCDIR_NATIVE'><glossterm>STAGING_INCDIR_NATIVE</glossterm>
            <glossdef>
                <para>
                    Specifies the path to the <filename>/usr/include</filename>
                    subdirectory of the sysroot directory for the build host.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-STAGING_LIBDIR'><glossterm>STAGING_LIBDIR</glossterm>
            <glossdef>
                <para>
                    Specifies the path to the <filename>/usr/lib</filename>
                    subdirectory of the sysroot directory for the target for
                    which the current recipe is being built
                    (<link linkend='var-STAGING_DIR_HOST'><filename>STAGING_DIR_HOST</filename></link>).
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-STAGING_LIBDIR_NATIVE'><glossterm>STAGING_LIBDIR_NATIVE</glossterm>
            <glossdef>
                <para>
                    Specifies the path to the <filename>/usr/lib</filename>
                    subdirectory of the sysroot directory for the build host.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-STAGING_KERNEL_DIR'><glossterm>STAGING_KERNEL_DIR</glossterm>
            <glossdef>
                <para>
                    The directory with kernel headers that are required to build out-of-tree
                    modules.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-STAMP'><glossterm>STAMP</glossterm>
            <glossdef>
                <para>
                    Specifies the base path used to create recipe stamp files.
                    The path to an actual stamp file is constructed by evaluating this
                    string and then appending additional information.
                    Currently, the default assignment for <filename>STAMP</filename>
                    as set in the <filename>meta/conf/bitbake.conf</filename> file
                    is:
                    <literallayout class='monospaced'>
     STAMP = "${STAMPS_DIR}/${MULTIMACH_TARGET_SYS}/${PN}/${EXTENDPE}${PV}-${PR}"
                    </literallayout>
                    See <link linkend='var-STAMPS_DIR'><filename>STAMPS_DIR</filename></link>,
                    <link linkend='var-MULTIMACH_TARGET_SYS'><filename>MULTIMACH_TARGET_SYS</filename></link>,
                    <link linkend='var-PN'><filename>PN</filename></link>,
                    <link linkend='var-EXTENDPE'><filename>EXTENDPE</filename></link>,
                    <link linkend='var-PV'><filename>PV</filename></link>, and
                    <link linkend='var-PR'><filename>PR</filename></link> for related variable
                    information.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-STAMPS_DIR'><glossterm>STAMPS_DIR</glossterm>
            <glossdef>
                <para>
                    Specifies the base directory in which the OpenEmbedded
                    build system places stamps.
                    The default directory is
                    <filename>${TMPDIR}/stamps</filename>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SUMMARY'><glossterm>SUMMARY</glossterm>
            <glossdef>
                <para>The short (72 characters or less) summary of the binary package for packaging
                    systems such as <filename>opkg</filename>, <filename>rpm</filename> or
                    <filename>dpkg</filename>.
                    By default, <filename>SUMMARY</filename> is used to define
                    the <link linkend='var-DESCRIPTION'><filename>DESCRIPTION</filename></link>
                    variable if <filename>DESCRIPTION</filename> is not set
                    in the recipe.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SYSLINUX_DEFAULT_CONSOLE'><glossterm>SYSLINUX_DEFAULT_CONSOLE</glossterm>
            <glossdef>
                <para>
                    Specifies the kernel boot default console.
                    If you want to use a console other than the default,
                    set this variable in your recipe as follows where "X" is
                    the console number you want to use:
                    <literallayout class='monospaced'>
     SYSLINUX_DEFAULT_CONSOLE = "console=ttyX"
                    </literallayout>
                </para>

                <para>
                    The
                    <link linkend='ref-classes-syslinux'><filename>syslinux</filename></link>
                    class initially sets this variable to null but then checks
                    for a value later.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SYSLINUX_OPTS'><glossterm>SYSLINUX_OPTS</glossterm>
            <glossdef>
                <para>
                    Lists additional options to add to the syslinux file.
                    You need to set this variable in your recipe.
                    If you want to list multiple options, separate the options
                    with a semicolon character (<filename>;</filename>).
                </para>

                <para>
                    The
                    <link linkend='ref-classes-syslinux'><filename>syslinux</filename></link>
                    class uses this variable to create a set of options.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SYSLINUX_SERIAL'><glossterm>SYSLINUX_SERIAL</glossterm>
            <glossdef>
                <para>
                    Specifies the alternate serial port or turns it off.
                    To turn off serial, set this variable to an empty string
                    in your recipe.
                    The variable's default value is set in the
                    <link linkend='ref-classes-syslinux'><filename>syslinux</filename></link>
                    as follows:
                    <literallayout class='monospaced'>
     SYSLINUX_SERIAL ?= "0 115200"
                    </literallayout>
                    The class checks for and uses the variable as needed.                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SYSLINUX_SPLASH'><glossterm>SYSLINUX_SPLASH</glossterm>
            <glossdef>
                <para>
                    An <filename>.LSS</filename> file used as the background
                    for the VGA boot menu when you are using the boot menu.
                    You need to set this variable in your recipe.
                </para>

                <para>
                    The
                    <link linkend='ref-classes-syslinux'><filename>syslinux</filename></link>
                    class checks for this variable and if found, the
                    OpenEmbedded build system installs the splash screen.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SYSLINUX_SERIAL_TTY'><glossterm>SYSLINUX_SERIAL_TTY</glossterm>
            <glossdef>
                <para>
                    Specifies the alternate console=tty... kernel boot argument.
                    The variable's default value is set in the
                    <link linkend='ref-classes-syslinux'><filename>syslinux</filename></link>
                    as follows:
                    <literallayout class='monospaced'>
     SYSLINUX_SERIAL_TTY ?= "console=ttyS0,115200"
                    </literallayout>
                    The class checks for and uses the variable as needed.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SYSROOT_PREPROCESS_FUNCS'><glossterm>SYSROOT_PREPROCESS_FUNCS</glossterm>
            <glossdef>
                <para>
                    A list of functions to execute after files are staged into
                    the sysroot.
                    These functions are usually used to apply additional
                    processing on the staged files, or to stage additional
                    files.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SYSTEMD_AUTO_ENABLE'><glossterm>SYSTEMD_AUTO_ENABLE</glossterm>
            <glossdef>
                <para>
                    When inheriting the
                    <link linkend='ref-classes-systemd'><filename>systemd</filename></link>
                    class, this variable specifies whether the service you have
                    specified in
                    <link linkend='var-SYSTEMD_SERVICE'><filename>SYSTEMD_SERVICE</filename></link>
                    should be started automatically or not.
                    By default, the service is enabled to automatically start
                    at boot time.
                    The default setting is in the
                    <link linkend='ref-classes-systemd'><filename>systemd</filename></link>
                    class as follows:
                    <literallayout class='monospaced'>
     SYSTEMD_AUTO_ENABLE ??= "enable"
                    </literallayout>
                    You can disable the service by setting the variable to
                    "disable".
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SYSTEMD_PACKAGES'><glossterm>SYSTEMD_PACKAGES</glossterm>
            <glossdef>
                <para>
                    When inheriting the
                    <link linkend='ref-classes-systemd'><filename>systemd</filename></link>
                    class, this variable locates the systemd unit files when
                    they are not found in the main recipe's package.
                    By default, the
                    <filename>SYSTEMD_PACKAGES</filename> variable is set
                    such that the systemd unit files are assumed to reside in
                    the recipes main package:
                    <literallayout class='monospaced'>
     SYSTEMD_PACKAGES ?= "${PN}"
                    </literallayout>
                    If these unit files are not in this recipe's main
                    package, you need to use
                    <filename>SYSTEMD_PACKAGES</filename> to list the package
                    or packages in which the build system can find the systemd
                    unit files.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SYSTEMD_SERVICE'><glossterm>SYSTEMD_SERVICE</glossterm>
            <glossdef>
                <para>
                    When inheriting the
                    <link linkend='ref-classes-systemd'><filename>systemd</filename></link>
                    class, this variable specifies the systemd service name for
                    a package.
                </para>

                <para>
                    When you specify this file in your recipe, use a package
                    name override to indicate the package to which the value
                    applies.
                    Here is an example from the connman recipe:
                    <literallayout class='monospaced'>
     SYSTEMD_SERVICE_${PN} = "connman.service"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-SYSVINIT_ENABLED_GETTYS'><glossterm>SYSVINIT_ENABLED_GETTYS</glossterm>
            <glossdef>
                <para>
                    When using
                    <ulink url='&YOCTO_DOCS_DEV_URL;#new-recipe-enabling-system-services'>SysVinit</ulink>,
                    specifies a space-separated list of the virtual terminals
                    that should be running a
                    <ulink url='http://en.wikipedia.org/wiki/Getty_%28Unix%29'>getty</ulink>
                    (allowing login), assuming
                    <link linkend='var-USE_VT'><filename>USE_VT</filename></link>
                    is not set to "0".
                </para>

                <para>
                    The default value for
                    <filename>SYSVINIT_ENABLED_GETTYS</filename> is "1"
                    (i.e. only run a getty on the first virtual terminal).
                </para>
            </glossdef>
        </glossentry>

    </glossdiv>

    <glossdiv id='var-glossary-t'><title>T</title>

        <glossentry id='var-T'><glossterm>T</glossterm>
            <glossdef>
                <para>This variable points to a directory were BitBake places
                    temporary files, which consist mostly of task logs and
                    scripts, when building a particular recipe.
                    The variable is typically set as follows:
                    <literallayout class='monospaced'>
     T = "${WORKDIR}/temp"
                    </literallayout>
                    The <link linkend='var-WORKDIR'><filename>WORKDIR</filename></link>
                    is the directory into which BitBake unpacks and builds the
                    recipe.
                    The default <filename>bitbake.conf</filename> file sets this variable.</para>
                    <para>The <filename>T</filename> variable is not to be confused with
                    the <link linkend='var-TMPDIR'><filename>TMPDIR</filename></link> variable,
                    which points to the root of the directory tree where BitBake
                    places the output of an entire build.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TARGET_ARCH'><glossterm>TARGET_ARCH</glossterm>
            <glossdef>
                <para>
                    The target machine's architecture.
                    The OpenEmbedded build system supports many
                    architectures.
                    Here is an example list of architectures supported.
                    This list is by no means complete as the architecture
                    is configurable:
                    <literallayout class='monospaced'>
     arm
     i586
     x86_64
     powerpc
     powerpc64
     mips
     mipsel
                    </literallayout>
                    For additional information on machine architectures, see
                    the
                    <link linkend='var-TUNE_ARCH'><filename>TUNE_ARCH</filename></link>
                    variable.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TARGET_AS_ARCH'><glossterm>TARGET_AS_ARCH</glossterm>
            <glossdef>
                <para>
                    Specifies architecture-specific assembler flags for the
                    target system.
                    <filename>TARGET_AS_ARCH</filename> is initialized from
                    <link linkend='var-TUNE_ASARGS'><filename>TUNE_ASARGS</filename></link>
                    by default in the BitBake configuration file
                    (<filename>meta/conf/bitbake.conf</filename>):
                    <literallayout class='monospaced'>
     TARGET_AS_ARCH = "${TUNE_ASARGS}"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TARGET_CC_ARCH'><glossterm>TARGET_CC_ARCH</glossterm>
            <glossdef>
                <para>
                    Specifies architecture-specific C compiler flags for the
                    target system.
                    <filename>TARGET_CC_ARCH</filename> is initialized from
                    <link linkend='var-TUNE_CCARGS'><filename>TUNE_CCARGS</filename></link>
                    by default.
                    <note>
                        It is a common workaround to append
                        <link linkend='var-LDFLAGS'><filename>LDFLAGS</filename></link>
                        to <filename>TARGET_CC_ARCH</filename>
                        in recipes that build software for the target that
                        would not otherwise respect the exported
                        <filename>LDFLAGS</filename> variable.
                    </note>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TARGET_CC_KERNEL_ARCH'><glossterm>TARGET_CC_KERNEL_ARCH</glossterm>
            <glossdef>
                <para>
                    This is a specific kernel compiler flag for a CPU or
                    Application Binary Interface (ABI) tune.
                    The flag is used rarely and only for cases where a
                    userspace
                    <link linkend='var-TUNE_CCARGS'><filename>TUNE_CCARGS</filename></link>
                    is not compatible with the kernel compilation.
                    The <filename>TARGET_CC_KERNEL_ARCH</filename> variable
                    allows the kernel (and associated modules) to use a
                    different configuration.
                    See the
                    <filename>meta/conf/machine/include/arm/feature-arm-thumb.inc</filename>
                    file in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>
                    for an example.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TARGET_CFLAGS'><glossterm>TARGET_CFLAGS</glossterm>
            <glossdef>
                <para>
                    Specifies the flags to pass to the C compiler when building
                    for the target.
                    When building in the target context,
                    <link linkend='var-CFLAGS'><filename>CFLAGS</filename></link>
                    is set to the value of this variable by default.
                </para>

                <para>
                    Additionally, the SDK's environment setup script sets
                    the
                    <link linkend='var-CFLAGS'><filename>CFLAGS</filename></link>
                    variable in the environment to the
                    <filename>TARGET_CFLAGS</filename> value so that
                    executables built using the SDK also have the flags
                    applied.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TARGET_CPPFLAGS'><glossterm>TARGET_CPPFLAGS</glossterm>
            <glossdef>
                <para>
                    Specifies the flags to pass to the C pre-processor
                    (i.e. to both the C and the C++ compilers) when building
                    for the target.
                    When building in the target context,
                    <link linkend='var-CPPFLAGS'><filename>CPPFLAGS</filename></link>
                    is set to the value of this variable by default.
                </para>

                <para>
                    Additionally, the SDK's environment setup script sets
                    the
                    <link linkend='var-CPPFLAGS'><filename>CPPFLAGS</filename></link>
                    variable in the environment to the
                    <filename>TARGET_CPPFLAGS</filename> value so that
                    executables built using the SDK also have the flags
                    applied.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TARGET_CXXFLAGS'><glossterm>TARGET_CXXFLAGS</glossterm>
            <glossdef>
                <para>
                    Specifies the flags to pass to the C++ compiler when
                    building for the target.
                    When building in the target context,
                    <link linkend='var-CXXFLAGS'><filename>CXXFLAGS</filename></link>
                    is set to the value of this variable by default.
                </para>

                <para>
                    Additionally, the SDK's environment setup script sets
                    the
                    <link linkend='var-CXXFLAGS'><filename>CXXFLAGS</filename></link>
                    variable in the environment to the
                    <filename>TARGET_CXXFLAGS</filename> value so that
                    executables built using the SDK also have the flags
                    applied.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TARGET_FPU'><glossterm>TARGET_FPU</glossterm>
            <glossdef>
                <para>Specifies the method for handling FPU code.
                    For FPU-less targets, which include most ARM CPUs, the variable must be
                    set to "soft".
                    If not, the kernel emulation gets used, which results in a performance penalty.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TARGET_LD_ARCH'><glossterm>TARGET_LD_ARCH</glossterm>
            <glossdef>
                <para>
                    Specifies architecture-specific linker flags for the
                    target system.
                    <filename>TARGET_LD_ARCH</filename> is initialized from
                    <link linkend='var-TUNE_LDARGS'><filename>TUNE_LDARGS</filename></link>
                    by default in the BitBake configuration file
                    (<filename>meta/conf/bitbake.conf</filename>):
                    <literallayout class='monospaced'>
     TARGET_LD_ARCH = "${TUNE_LDARGS}"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TARGET_LDFLAGS'><glossterm>TARGET_LDFLAGS</glossterm>
            <glossdef>
                <para>
                    Specifies the flags to pass to the linker when building
                    for the target.
                    When building in the target context,
                    <link linkend='var-LDFLAGS'><filename>LDFLAGS</filename></link>
                    is set to the value of this variable by default.
                </para>

                <para>
                    Additionally, the SDK's environment setup script sets
                    the
                    <link linkend='var-LDFLAGS'><filename>LDFLAGS</filename></link>
                    variable in the environment to the
                    <filename>TARGET_LDFLAGS</filename> value so that
                    executables built using the SDK also have the flags
                    applied.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TARGET_OS'><glossterm>TARGET_OS</glossterm>
            <glossdef>
                <para>Specifies the target's operating system.
                    The variable can be set to "linux" for <filename>glibc</filename>-based systems and
                    to "linux-uclibc" for <filename>uclibc</filename>.
                    For ARM/EABI targets, there are also "linux-gnueabi" and
                    "linux-uclibc-gnueabi" values possible.</para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TCLIBC'><glossterm>TCLIBC</glossterm>
            <glossdef>
                <para>
                    Specifies the GNU standard C library (<filename>libc</filename>)
                    variant to use during the build process.
                    This variable replaces <filename>POKYLIBC</filename>, which is no longer
                    supported.
                </para>
                <para>
                    You can select "glibc" or "uclibc".
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TCMODE'><glossterm>TCMODE</glossterm>
            <glossdef>
                <para>
                    Specifies the toolchain selector.
                    <filename>TCMODE</filename> controls the characteristics
                    of the generated packages and images by telling the
                    OpenEmbedded build system which toolchain profile to use.
                    By default, the OpenEmbedded build system builds its own
                    internal toolchain.
                    The variable's default value is "default", which uses
                    that internal toolchain.
                    <note>
                        If <filename>TCMODE</filename> is set to a value
                        other than "default", then it is your responsibility
                        to ensure that the toolchain is compatible with the
                        default toolchain.
                        Using older or newer versions of these components
                        might cause build problems.
                        See the
                        <ulink url='&YOCTO_RELEASE_NOTES;'>Release Notes</ulink>
                        for the specific components with which the toolchain
                        must be compatible.
                    </note>
                </para>

                <para>
                    With additional layers, it is possible to use a pre-compiled
                    external toolchain.
                    One example is the Sourcery G++ Toolchain.
                    The support for this toolchain resides in the separate
                    <filename>meta-sourcery</filename> layer at
                    <ulink url='http://github.com/MentorEmbedded/meta-sourcery/'></ulink>.
                    You can use <filename>meta-sourcery</filename> as a
                    template for adding support for other external toolchains.
                </para>

                <para>
                    The <filename>TCMODE</filename> variable points the build
                    system to a file in
                    <filename>conf/distro/include/tcmode-${TCMODE}.inc</filename>.
                    Thus, for <filename>meta-sourcery</filename>,
                    which has <filename>conf/distro/include/tcmode-external-sourcery.inc</filename>,
                    you would set the variable as follows:
                    <literallayout class='monospaced'>
     TCMODE ?= "external-sourcery"
                    </literallayout>
                </para>

                <para>
                    The variable is similar to
                    <link linkend='var-TCLIBC'><filename>TCLIBC</filename></link>,
                    which controls the variant of the GNU standard C library
                    (<filename>libc</filename>) used during the build process:
                    <filename>glibc</filename> or <filename>uclibc</filename>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TEST_EXPORT_DIR'><glossterm>TEST_EXPORT_DIR</glossterm>
            <glossdef>
                <para>
                    The location the OpenEmbedded build system uses to export
                    tests when the
                    <link linkend='var-TEST_EXPORT_ONLY'><filename>TEST_EXPORT_ONLY</filename></link>
                    variable is set to "1".
                </para>

                <para>
                    The <filename>TEST_EXPORT_DIR</filename> variable defaults
                    to <filename>"${TMPDIR}/testimage/${PN}"</filename>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TEST_EXPORT_ONLY'><glossterm>TEST_EXPORT_ONLY</glossterm>
            <glossdef>
                <para>
                    Specifies to export the tests only.
                    Set this variable to "1" if you do not want to run the
                    tests but you want them to be exported in a manner that
                    you to run them outside of the build system.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TEST_IMAGE'><glossterm>TEST_IMAGE</glossterm>
            <glossdef>
                <para>
                    Automatically runs the series of automated tests for
                    images when an image is successfully built.
                </para>

                <para>
                    These tests are written in Python making use of the
                    <filename>unittest</filename> module, and the majority of
                    them run commands on the target system over
                    <filename>ssh</filename>.
                    You can set this variable to "1" in your
                    <filename>local.conf</filename> file in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>
                    to have the OpenEmbedded build system automatically run
                    these tests after an image successfully builds:
                    <literallayout class='monospaced'>
     TEST_IMAGE = "1"
                    </literallayout>
                    For more information on enabling, running, and writing
                    these tests, see the
                    "<ulink url='&YOCTO_DOCS_DEV_URL;#performing-automated-runtime-testing'>Performing Automated Runtime Testing</ulink>"
                    section in the Yocto Project Development Manual and the
                    "<link linkend='ref-classes-testimage'><filename>testimage.bbclass</filename></link>"
                    section.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TEST_LOG_DIR'><glossterm>TEST_LOG_DIR</glossterm>
            <glossdef>
                <para>
                    Holds the SSH log and the boot log for QEMU machines.
                    The <filename>TEST_LOG_DIR</filename> variable defaults
                    to <filename>"${WORKDIR}/testimage"</filename>.
                    <note>
                        Actual test results reside in the task log
                        (<filename>log.do_testimage</filename>), which is in
                        the <filename>${WORKDIR}/temp/</filename> directory.
                    </note>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TEST_POWERCONTROL_CMD'><glossterm>TEST_POWERCONTROL_CMD</glossterm>
            <glossdef>
                <para>
                    For automated hardware testing, specifies the command to
                    use to control the power of the target machine under test.
                    Typically, this command would point to a script that
                    performs the appropriate action (e.g. interacting
                    with a web-enabled power strip).
                    The specified command should expect to receive as the last
                    argument "off", "on" or "cycle" specifying to power off,
                    on, or cycle (power off and then power on) the device,
                    respectively.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TEST_POWERCONTROL_EXTRA_ARGS'><glossterm>TEST_POWERCONTROL_EXTRA_ARGS</glossterm>
            <glossdef>
                <para>
                    For automated hardware testing, specifies additional
                    arguments to pass through to the command specified in
                    <link linkend='var-TEST_POWERCONTROL_CMD'><filename>TEST_POWERCONTROL_CMD</filename></link>.
                    Setting <filename>TEST_POWERCONTROL_EXTRA_ARGS</filename>
                    is optional.
                    You can use it if you wish, for example, to separate the
                    machine-specific and non-machine-specific parts of the
                    arguments.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TEST_QEMUBOOT_TIMEOUT'><glossterm>TEST_QEMUBOOT_TIMEOUT</glossterm>
            <glossdef>
                <para>
                    The time in seconds allowed for an image to boot before
                    automated runtime tests begin to run against an
                    image.
                    The default timeout period to allow the boot process to
                    reach the login prompt is 500 seconds.
                    You can specify a different value in the
                    <filename>local.conf</filename> file.
                </para>

                <para>
                    For more information on testing images, see the
                    "<ulink url='&YOCTO_DOCS_DEV_URL;#performing-automated-runtime-testing'>Performing Automated Runtime Testing</ulink>"
                    section in the Yocto Project Development Manual.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TEST_SERIALCONTROL_CMD'><glossterm>TEST_SERIALCONTROL_CMD</glossterm>
            <glossdef>
                <para>
                    For automated hardware testing, specifies the command
                    to use to connect to the serial console of the target
                    machine under test.
                    This command simply needs to connect to the serial console
                    and forward that connection to standard input and output
                    as any normal terminal program does.
                </para>

                <para>
                    For example, to use the Picocom terminal program on
                    serial device <filename>/dev/ttyUSB0</filename> at
                    115200bps, you would set the variable as follows:
                    <literallayout class='monospaced'>
     TEST_SERIALCONTROL_CMD = "picocom /dev/ttyUSB0 -b 115200"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TEST_SERIALCONTROL_EXTRA_ARGS'><glossterm>TEST_SERIALCONTROL_EXTRA_ARGS</glossterm>
            <glossdef>
                <para>
                    For automated hardware testing, specifies additional
                    arguments to pass through to the command specified in
                    <link linkend='var-TEST_SERIALCONTROL_CMD'><filename>TEST_SERIALCONTROL_CMD</filename></link>.
                    Setting <filename>TEST_SERIALCONTROL_EXTRA_ARGS</filename>
                    is optional.
                    You can use it if you wish, for example, to separate the
                    machine-specific and non-machine-specific parts of the
                    command.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TEST_SERVER_IP'><glossterm>TEST_SERVER_IP</glossterm>
            <glossdef>
                <para>
                    The IP address of the build machine (host machine).
                    This IP address is usually automatically detected.
                    However, if detection fails, this variable needs to be set
                    to the IP address of the build machine (i.e. where
                    the build is taking place).
                    <note>
                        The <filename>TEST_SERVER_IP</filename> variable
                        is only used for a small number of tests such as
                        the "smart" test suite, which needs to download
                        packages from <filename>DEPLOY_DIR/rpm</filename>.
                    </note>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TEST_TARGET'><glossterm>TEST_TARGET</glossterm>
            <glossdef>
                <para>
                    Specifies the target controller to use when running tests
                    against a test image.
                    The default controller to use is "qemu":
                    <literallayout class='monospaced'>
     TEST_TARGET = "qemu"
                    </literallayout>
                    A target controller is a class that defines how an
                    image gets deployed on a target and how a target is started.
                    A layer can extend the controllers by adding a module
                    in the layer's <filename>/lib/oeqa/controllers</filename>
                    directory and by inheriting the
                    <filename>BaseTarget</filename> class, which is an abstract
                    class that cannot be used as a value of
                    <filename>TEST_TARGET</filename>.
                </para>

                <para>
                    You can provide the following arguments with
                    <filename>TEST_TARGET</filename>:
                    <itemizedlist>
                        <listitem><para><emphasis>"qemu" and "QemuTarget":</emphasis>
                            Boots a QEMU image and runs the tests.
                            See the
                            "<ulink url='&YOCTO_DOCS_DEV_URL;#qemu-image-enabling-tests'>Enabling Runtime Tests on QEMU</ulink>"
                            section in the Yocto Project Development Manual for
                            more information.
                            </para></listitem>
                        <listitem><para><emphasis>"simpleremote" and "SimpleRemoteTarget":</emphasis>
                            Runs the tests on target hardware that is already
                            up and running.
                            The hardware can be on the network or it can be
                            a device running an image on QEMU.
                            You must also set
                            <link linkend='var-TEST_TARGET_IP'><filename>TEST_TARGET_IP</filename></link>
                            when you use "simpleremote" or "SimpleRemoteTarget".
                            <note>
                                This argument is defined in
                                <filename>meta/lib/oeqa/targetcontrol.py</filename>.
                                The small caps names are kept for compatibility
                                reasons.
                            </note>
                            </para></listitem>
                        <listitem><para><emphasis>"GummibootTarget":</emphasis>
                            Automatically deploys and runs tests on an
                            EFI-enabled machine that has a master image
                            installed.
                            <note>
                                This argument is defined in
                                <filename>meta/lib/oeqa/controllers/masterimage.py</filename>.
                            </note>
                            </para></listitem>
                    </itemizedlist>
                </para>

                <para>
                    For information on running tests on hardware, see the
                    "<ulink url='&YOCTO_DOCS_DEV_URL;#hardware-image-enabling-tests'>Enabling Runtime Tests on Hardware</ulink>"
                    section in the Yocto Project Development Manual.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TEST_TARGET_IP'><glossterm>TEST_TARGET_IP</glossterm>
            <glossdef>
                <para>
                    The IP address of your hardware under test.
                    The <filename>TEST_TARGET_IP</filename> variable has no
                    effect when
                    <link linkend='var-TEST_TARGET'><filename>TEST_TARGET</filename></link>
                    is set to "qemu".
                </para>

                <para>
                    When you specify the IP address, you can also include a
                    port.
                    Here is an example:
                    <literallayout class='monospaced'>
     TEST_TARGET_IP = "192.168.1.4:2201"
                    </literallayout>
                    Specifying a port is useful when SSH is started on a
                    non-standard port or in cases when your hardware under test
                    is behind a firewall or network that is not directly
                    accessible from your host and you need to do port address
                    translation.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TEST_SUITES'><glossterm>TEST_SUITES</glossterm>
            <glossdef>
                <para>
                    An ordered list of tests (modules) to run against
                    an image when performing automated runtime testing.
                </para>

                <para>
                    The OpenEmbedded build system provides a core set of tests
                    that can be used against images.
                    <note>
                        Currently, there is only support for running these tests
                        under QEMU.
                    </note>
                    Tests include <filename>ping</filename>,
                    <filename>ssh</filename>, <filename>df</filename> among
                    others.
                    You can add your own tests to the list of tests by
                    appending <filename>TEST_SUITES</filename> as follows:
                    <literallayout class='monospaced'>
     TEST_SUITES_append = " <replaceable>mytest</replaceable>"
                    </literallayout>
                    Alternatively, you can provide the "auto" option to
                    have all applicable tests run against the image.
                    <literallayout class='monospaced'>
     TEST_SUITES_append = " auto"
                    </literallayout>
                    Using this option causes the build system to automatically
                    run tests that are applicable to the image.
                    Tests that are not applicable are skipped.
                </para>

                <para>
                    The order in which tests are run is important.
                    Tests that depend on another test must appear later in the
                    list than the test on which they depend.
                    For example, if you append the list of tests with two
                    tests (<filename>test_A</filename> and
                    <filename>test_B</filename>) where
                    <filename>test_B</filename> is dependent on
                    <filename>test_A</filename>, then you must order the tests
                    as follows:
                    <literallayout class='monospaced'>
     TEST_SUITES = " test_A test_B"
                    </literallayout>
                </para>

                <para>
                    For more information on testing images, see the
                    "<ulink url='&YOCTO_DOCS_DEV_URL;#performing-automated-runtime-testing'>Performing Automated Runtime Testing</ulink>"
                    section in the Yocto Project Development Manual.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-THISDIR'><glossterm>THISDIR</glossterm>
            <glossdef>
                <para>
                    The directory in which the file BitBake is currently
                    parsing is located.
                    Do not manually set this variable.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TMPDIR'><glossterm>TMPDIR</glossterm>
            <glossdef>
                <para>
                    This variable is the base directory the OpenEmbedded
                    build system uses for all build output and intermediate
                    files (other than the shared state cache).
                    By default, the <filename>TMPDIR</filename> variable points
                    to <filename>tmp</filename> within the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
                </para>

                <para>
                    If you want to establish this directory in a location other
                    than the default, you can uncomment and edit the following
                    statement in the
                    <filename>conf/local.conf</filename> file in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>:
                    <literallayout class='monospaced'>
     #TMPDIR = "${TOPDIR}/tmp"
                    </literallayout>
                    An example use for this scenario is to set
                    <filename>TMPDIR</filename> to a local disk, which does
                    not use NFS, while having the Build Directory use NFS.
                </para>

                <para>
                    The filesystem used by <filename>TMPDIR</filename> must
                    have standard filesystem semantics (i.e. mixed-case files
                    are unique, POSIX file locking, and persistent inodes).
                    Due to various issues with NFS and bugs in some
                    implementations, NFS does not meet this minimum
                    requirement.
                    Consequently, <filename>TMPDIR</filename> cannot be on
                    NFS.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TOOLCHAIN_HOST_TASK'><glossterm>TOOLCHAIN_HOST_TASK</glossterm>
            <glossdef>
                <para>
                    This variable lists packages the OpenEmbedded build system
                    uses when building an SDK, which contains a
                    cross-development environment.
                    The packages specified by this variable are part of the
                    toolchain set that runs on the
                    <link linkend='var-SDKMACHINE'><filename>SDKMACHINE</filename></link>,
                    and each package should usually have the prefix
                    "nativesdk-".
                    When building an SDK using
                    <filename>bitbake -c populate_sdk &lt;imagename&gt;</filename>,
                    a default list of packages is set in this variable, but
                    you can add additional packages to the list.
                </para>

                <para>
                    For background information on cross-development toolchains
                    in the Yocto Project development environment, see the
                    "<link linkend='cross-development-toolchain-generation'>Cross-Development Toolchain Generation</link>"
                    section.
                    For information on setting up a cross-development
                    environment, see the
                    "<ulink url='&YOCTO_DOCS_ADT_URL;#installing-the-adt'>Installing the ADT and Toolchains</ulink>"
                    section in the Yocto Project Application Developer's Guide.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TOOLCHAIN_TARGET_TASK'><glossterm>TOOLCHAIN_TARGET_TASK</glossterm>
            <glossdef>
                <para>
                    This variable lists packages the OpenEmbedded build system
                    uses when it creates the target part of an SDK
                    (i.e. the part built for the target hardware), which
                    includes libraries and headers.
                </para>

                <para>
                    For background information on cross-development toolchains
                    in the Yocto Project development environment, see the
                    "<link linkend='cross-development-toolchain-generation'>Cross-Development Toolchain Generation</link>"
                    section.
                    For information on setting up a cross-development
                    environment, see the
                    "<ulink url='&YOCTO_DOCS_ADT_URL;#installing-the-adt'>Installing the ADT and Toolchains</ulink>"
                    section in the Yocto Project Application Developer's Guide.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TOPDIR'><glossterm>TOPDIR</glossterm>
            <glossdef>
                <para>
                    The top-level
                    <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
                    BitBake automatically sets this variable when you
                    initialize your build environment using either
                    <link linkend='structure-core-script'><filename>&OE_INIT_FILE;</filename></link>
                    or
                    <link linkend='structure-memres-core-script'><filename>oe-init-build-env-memres</filename></link>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TRANSLATED_TARGET_ARCH'><glossterm>TRANSLATED_TARGET_ARCH</glossterm>
            <glossdef>
                <para>
                    A sanitized version of
                    <link linkend='var-TARGET_ARCH'><filename>TARGET_ARCH</filename></link>.
                    This variable is used where the architecture is needed in
                    a value where underscores are not allowed, for example
                    within package filenames.
                    In this case, dash characters replace any underscore
                    characters used in TARGET_ARCH.
                </para>

                <para>
                    Do not edit this variable.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TUNE_ARCH'><glossterm>TUNE_ARCH</glossterm>
            <glossdef>
                <para>
                    The GNU canonical architecture for a specific architecture
                    (i.e. <filename>arm</filename>,
                    <filename>armeb</filename>,
                    <filename>mips</filename>,
                    <filename>mips64</filename>, and so forth).
                    BitBake uses this value to setup configuration.
                </para>

                <para>
                    <filename>TUNE_ARCH</filename> definitions are specific to
                    a given architecture.
                    The definitions can be a single static definition, or
                    can be dynamically adjusted.
                    You can see details for a given CPU family by looking at
                    the architecture's <filename>README</filename> file.
                    For example, the
                    <filename>meta/conf/machine/include/mips/README</filename>
                    file in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>
                    provides information for <filename>TUNE_ARCH</filename>
                    specific to the <filename>mips</filename> architecture.
                </para>

                <para>
                    <filename>TUNE_ARCH</filename> is tied closely to
                    <link linkend='var-TARGET_ARCH'><filename>TARGET_ARCH</filename></link>,
                    which defines the target machine's architecture.
                    The BitBake configuration file
                    (<filename>meta/conf/bitbake.conf</filename>) sets
                    <filename>TARGET_ARCH</filename> as follows:
                    <literallayout class='monospaced'>
     TARGET_ARCH = "${TUNE_ARCH}"
                    </literallayout>
                </para>

                <para>
                    The following list, which is by no means complete since
                    architectures are configurable, shows supported machine
                    architectures:
                    <literallayout class='monospaced'>
     arm
     i586
     x86_64
     powerpc
     powerpc64
     mips
     mipsel
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TUNE_ASARGS'><glossterm>TUNE_ASARGS</glossterm>
            <glossdef>
                <para>
                    Specifies architecture-specific assembler flags for
                    the target system.
                    The set of flags is based on the selected tune features.
                    <filename>TUNE_ASARGS</filename> is set using
                    the tune include files, which are typically under
                    <filename>meta/conf/machine/include/</filename> and are
                    influenced through <filename>TUNE_FEATURES</filename>.
                    For example, the
                    <filename>meta/conf/machine/include/x86/arch-x86.inc</filename>
                    file defines the flags for the x86 architecture as follows:
                    <literallayout class='monospaced'>
     TUNE_ASARGS += "${@bb.utils.contains("TUNE_FEATURES", "mx32", "-x32", "", d)}"
                    </literallayout>
                    <note>
                        Board Support Packages (BSPs) can supply their own
                        set of flags.
                    </note>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TUNE_CCARGS'><glossterm>TUNE_CCARGS</glossterm>
            <glossdef>
                <para>
                    Specifies architecture-specific C compiler flags for
                    the target system.
                    The set of flags is based on the selected tune features.
                    <filename>TUNE_CCARGS</filename> is set using
                    the tune include files, which are typically under
                    <filename>meta/conf/machine/include/</filename> and are
                    influenced through <filename>TUNE_FEATURES</filename>.
                    <note>
                        Board Support Packages (BSPs) can supply their own
                        set of flags.
                    </note>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TUNE_LDARGS'><glossterm>TUNE_LDARGS</glossterm>
            <glossdef>
                <para>
                    Specifies architecture-specific linker flags for
                    the target system.
                    The set of flags is based on the selected tune features.
                    <filename>TUNE_LDARGS</filename> is set using
                    the tune include files, which are typically under
                    <filename>meta/conf/machine/include/</filename> and are
                    influenced through <filename>TUNE_FEATURES</filename>.
                    For example, the
                    <filename>meta/conf/machine/include/x86/arch-x86.inc</filename>
                    file defines the flags for the x86 architecture as follows:
                    <literallayout class='monospaced'>
     TUNE_LDARGS += "${@bb.utils.contains("TUNE_FEATURES", "mx32", "-m elf32_x86_64", "", d)}"
                    </literallayout>
                    <note>
                        Board Support Packages (BSPs) can supply their own
                        set of flags.
                    </note>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TUNE_FEATURES'><glossterm>TUNE_FEATURES</glossterm>
            <glossdef>
                <para>
                    Features used to "tune" a compiler for optimal use
                    given a specific processor.
                    The features are defined within the tune files and allow
                    arguments (i.e. <filename>TUNE_*ARGS</filename>) to be
                    dynamically generated based on the features.
                </para>

                <para>
                    The OpenEmbedded build system verifies the features
                    to be sure they are not conflicting and that they are
                    supported.
                </para>

                <para>
                    The BitBake configuration file
                    (<filename>meta/conf/bitbake.conf</filename>) defines
                    <filename>TUNE_FEATURES</filename> as follows:
                    <literallayout class='monospaced'>
     TUNE_FEATURES ??= "${TUNE_FEATURES_tune-${DEFAULTTUNE}}"
                    </literallayout>
                    See the
                    <link linkend='var-DEFAULTTUNE'><filename>DEFAULTTUNE</filename></link>
                    variable for more information.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TUNE_PKGARCH'><glossterm>TUNE_PKGARCH</glossterm>
            <glossdef>
                <para>
                    The package architecture understood by the packaging
                    system to define the architecture, ABI, and tuning of
                    output packages.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TUNE_PKGARCH_tune'><glossterm>TUNE_PKGARCH_tune</glossterm>
            <glossdef>
                <para>
                    The CPU or Application Binary Interface (ABI) specific
                    tuning of the
                    <link linkend='var-TUNE_PKGARCH'><filename>TUNE_PKGARCH</filename></link>.
                </para>

                <para>
                    These tune-specific package architectures are defined in
                    the machine include files.
                    Here is an example of the "core2-32" tuning as used
                    in the
                    <filename>meta/conf/machine/include/tune-core2.inc</filename>
                    file:
                    <literallayout class='monospaced'>
     TUNE_PKGARCH_tune-core2-32 = "core2-32"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TUNEABI'><glossterm>TUNEABI</glossterm>
            <glossdef>
                <para>
                    An underlying Application Binary Interface (ABI) used by
                    a particular tuning in a given toolchain layer.
                    Providers that use prebuilt libraries can use the
                    <filename>TUNEABI</filename>,
                    <link linkend='var-TUNEABI_OVERRIDE'><filename>TUNEABI_OVERRIDE</filename></link>,
                    and
                    <link linkend='var-TUNEABI_WHITELIST'><filename>TUNEABI_WHITELIST</filename></link>
                    variables to check compatibility of tunings against their
                    selection of libraries.
                </para>

                <para>
                    If <filename>TUNEABI</filename> is undefined, then every
                    tuning is allowed.
                    See the
                    <link linkend='ref-classes-sanity'><filename>sanity</filename></link>
                    class to see how the variable is used.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TUNEABI_OVERRIDE'><glossterm>TUNEABI_OVERRIDE</glossterm>
            <glossdef>
                <para>
                    If set, the OpenEmbedded system ignores the
                    <link linkend='var-TUNEABI_WHITELIST'><filename>TUNEABI_WHITELIST</filename></link>
                    variable.
                    Providers that use prebuilt libraries can use the
                    <filename>TUNEABI_OVERRIDE</filename>,
                    <filename>TUNEABI_WHITELIST</filename>,
                    and
                    <link linkend='var-TUNEABI'><filename>TUNEABI</filename></link>
                    variables to check compatibility of a tuning against their
                    selection of libraries.
                </para>

                <para>
                    See the
                    <link linkend='ref-classes-sanity'><filename>sanity</filename></link>
                    class to see how the variable is used.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TUNEABI_WHITELIST'><glossterm>TUNEABI_WHITELIST</glossterm>
            <glossdef>
                <para>
                    A whitelist of permissible
                    <link linkend='var-TUNEABI'><filename>TUNEABI</filename></link>
                    values.
                    If <filename>TUNEABI_WHITELIST</filename> is not set,
                    all tunes are allowed.
                    Providers that use prebuilt libraries can use the
                    <filename>TUNEABI_WHITELIST</filename>,
                    <link linkend='var-TUNEABI_OVERRIDE'><filename>TUNEABI_OVERRIDE</filename></link>,
                    and <filename>TUNEABI</filename> variables to check
                    compatibility of a tuning against their selection of
                    libraries.
                </para>

                <para>
                    See the
                    <link linkend='ref-classes-sanity'><filename>sanity</filename></link>
                    class to see how the variable is used.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TUNECONFLICT'><glossterm>TUNECONFLICT[<replaceable>feature</replaceable>]</glossterm>
            <glossdef>
                <para>
                    Specifies CPU or Application Binary Interface (ABI)
                    tuning features that conflict with <replaceable>feature</replaceable>.
                </para>

                <para>
                    Known tuning conflicts are specified in the machine include
                    files in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>.
                    Here is an example from the
                    <filename>meta/conf/machine/include/mips/arch-mips.inc</filename>
                    include file that lists the "o32" and "n64" features as
                    conflicting with the "n32" feature:
                    <literallayout class='monospaced'>
     TUNECONFLICTS[n32] = "o32 n64"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-TUNEVALID'><glossterm>TUNEVALID[<replaceable>feature</replaceable>]</glossterm>
            <glossdef>
                <para>
                    Specifies a valid CPU or Application Binary Interface (ABI)
                    tuning feature.
                    The specified feature is stored as a flag.
                    Valid features are specified in the machine include files
                    (e.g. <filename>meta/conf/machine/include/arm/arch-arm.inc</filename>).
                    Here is an example from that file:
                    <literallayout class='monospaced'>
     TUNEVALID[bigendian] = "Enable big-endian mode."
                    </literallayout>
                    See the machine include files in the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>
                    for these features.
                </para>
            </glossdef>
        </glossentry>

    </glossdiv>

    <glossdiv id='var-glossary-u'><title>U</title>

        <glossentry id='var-UBOOT_CONFIG'><glossterm>UBOOT_CONFIG</glossterm>
            <glossdef>
                <para>
                    Configures the
                    <link linkend='var-UBOOT_MACHINE'><filename>UBOOT_MACHINE</filename></link>
                    and can also define
                    <link linkend='var-IMAGE_FSTYPES'><filename>IMAGE_FSTYPES</filename></link>
                    for individual cases.
                </para>

                <para>
                    Following is an example from the
                    <filename>meta-fsl-arm</filename> layer.
                    <literallayout class='monospaced'>
     UBOOT_CONFIG ??= "sd"
     UBOOT_CONFIG[sd] = "mx6qsabreauto_config,sdcard"
     UBOOT_CONFIG[eimnor] = "mx6qsabreauto_eimnor_config"
     UBOOT_CONFIG[nand] = "mx6qsabreauto_nand_config,ubifs"
     UBOOT_CONFIG[spinor] = "mx6qsabreauto_spinor_config"
                    </literallayout>
                    In this example, "sd" is selected as the configuration
                    of the possible four for the
                    <filename>UBOOT_MACHINE</filename>.
                    The "sd" configuration defines "mx6qsabreauto_config"
                    as the value for <filename>UBOOT_MACHINE</filename>, while
                    the "sdcard" specifies the
                    <filename>IMAGE_FSTYPES</filename> to use for the U-boot
                    image.
                </para>

                <para>
                    For more information on how the
                    <filename>UBOOT_CONFIG</filename> is handled, see the
                    <ulink url='http://git.yoctoproject.org/cgit/cgit.cgi/poky/tree/meta/classes/uboot-config.bbclass'><filename>uboot-config</filename></ulink>
                    class.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-UBOOT_ENTRYPOINT'><glossterm>UBOOT_ENTRYPOINT</glossterm>
            <glossdef>
                <para>
                    Specifies the entry point for the U-Boot image.
                    During U-Boot image creation, the
                    <filename>UBOOT_ENTRYPOINT</filename> variable is passed
                    as a command-line parameter to the
                    <filename>uboot-mkimage</filename> utility.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-UBOOT_LOADADDRESS'><glossterm>UBOOT_LOADADDRESS</glossterm>
            <glossdef>
                <para>
                    Specifies the load address for the U-Boot image.
                    During U-Boot image creation, the
                    <filename>UBOOT_LOADADDRESS</filename> variable is passed
                    as a command-line parameter to the
                    <filename>uboot-mkimage</filename> utility.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-UBOOT_LOCALVERSION'><glossterm>UBOOT_LOCALVERSION</glossterm>
            <glossdef>
                <para>
                    Appends a string to the name of the local version of the
                    U-Boot image.
                    For example, assuming the version of the U-Boot image
                    built was "2013.10, the full version string reported by
                    U-Boot would be "2013.10-yocto" given the following
                    statement:
                    <literallayout class='monospaced'>
     UBOOT_LOCALVERSION = "-yocto"
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-UBOOT_MACHINE'><glossterm>UBOOT_MACHINE</glossterm>
            <glossdef>
                <para>
                    Specifies the value passed on the
                    <filename>make</filename> command line when building
                    a U-Boot image.
                    The value indicates the target platform configuration.
                    You typically set this variable from the machine
                    configuration file (i.e.
                    <filename>conf/machine/<replaceable>machine_name</replaceable>.conf</filename>).
                </para>

                <para>
                    Please see the "Selection of Processor Architecture and
                    Board Type" section in the U-Boot README for valid values
                    for this variable.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-UBOOT_MAKE_TARGET'><glossterm>UBOOT_MAKE_TARGET</glossterm>
            <glossdef>
                <para>
                    Specifies the target called in the
                    <filename>Makefile</filename>.
                    The default target is "all".
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-UBOOT_SUFFIX'><glossterm>UBOOT_SUFFIX</glossterm>
            <glossdef>
                <para>
                    Points to the generated U-Boot extension.
                    For example, <filename>u-boot.sb</filename> has a
                    <filename>.sb</filename> extension.
                </para>

                <para>
                    The default U-Boot extension is
                    <filename>.bin</filename>
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-UBOOT_TARGET'><glossterm>UBOOT_TARGET</glossterm>
            <glossdef>
                <para>
                    Specifies the target used for building U-Boot.
                    The target is passed directly as part of the "make" command
                    (e.g. SPL and AIS).
                    If you do not specifically set this variable, the
                    OpenEmbedded build process passes and uses "all" for the
                    target during the U-Boot building process.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-USE_VT'><glossterm>USE_VT</glossterm>
            <glossdef>
                <para>
                    When using
                    <ulink url='&YOCTO_DOCS_DEV_URL;#new-recipe-enabling-system-services'>SysVinit</ulink>,
                    determines whether or not to run a
                    <ulink url='http://en.wikipedia.org/wiki/Getty_%28Unix%29'>getty</ulink>
                    on any virtual terminals in order to enable logging in
                    through those terminals.
                </para>

                <para>
                    The default value used for <filename>USE_VT</filename>
                    is "1" when no default value is specifically set.
                    Typically, you would set <filename>USE_VT</filename>
                    to "0" in the machine configuration file for machines
                    that do not have a graphical display attached and
                    therefore do not need virtual terminal functionality.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-USER_CLASSES'><glossterm>USER_CLASSES</glossterm>
            <glossdef>
                <para>
                    A list of classes to globally inherit.
                    These classes are used by the OpenEmbedded build system
                    to enable extra features (e.g.
                    <filename>buildstats</filename>,
                    <filename>image-mklibs</filename>, and so forth).
                </para>

                <para>
                    The default list is set in your
                    <filename>local.conf</filename> file:
                    <literallayout class='monospaced'>
     USER_CLASSES ?= "buildstats image-mklibs image-prelink"
                    </literallayout>
                    For more information, see
                    <filename>meta-yocto/conf/local.conf.sample</filename> in
                    the
                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-USERADD_ERROR_DYNAMIC'><glossterm>USERADD_ERROR_DYNAMIC</glossterm>
            <glossdef>
                <para>
                    Forces the OpenEmbedded build system to produce an error
                    if the user identification (<filename>uid</filename>) and
                    group identification (<filename>gid</filename>) values
                    are not defined in <filename>files/passwd</filename>
                    and <filename>files/group</filename> files.
                </para>

                <para>
                    The default behavior for the build system is to dynamically
                    apply <filename>uid</filename> and
                    <filename>gid</filename> values.
                    Consequently, the <filename>USERADD_ERROR_DYNAMIC</filename>
                    variable is by default not set.
                    If you plan on using statically assigned
                    <filename>gid</filename> and <filename>uid</filename>
                    values, you should set
                    the <filename>USERADD_ERROR_DYNAMIC</filename> variable in
                    your <filename>local.conf</filename> file as
                    follows:
                    <literallayout class='monospaced'>
     USERADD_ERROR_DYNAMIC = "1"
                    </literallayout>
                    Overriding the default behavior implies you are going to
                    also take steps to set static <filename>uid</filename> and
                    <filename>gid</filename> values through use of the
                    <link linkend='var-USERADDEXTENSION'><filename>USERADDEXTENSION</filename></link>,
                    <link linkend='var-USERADD_UID_TABLES'><filename>USERADD_UID_TABLES</filename></link>,
                    and
                    <link linkend='var-USERADD_GID_TABLES'><filename>USERADD_GID_TABLES</filename></link>
                    variables.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-USERADD_GID_TABLES'><glossterm>USERADD_GID_TABLES</glossterm>
            <glossdef>
                <para>
                    Specifies a password file to use for obtaining static
                    group identification (<filename>gid</filename>) values
                    when the OpenEmbedded build system adds a group to the
                    system during package installation.
                </para>

                <para>
                    When applying static group identification
                    (<filename>gid</filename>) values, the OpenEmbedded build
                    system looks in
                    <link linkend='var-BBPATH'><filename>BBPATH</filename></link>
                    for a <filename>files/group</filename> file and then applies
                    those <filename>uid</filename> values.
                    Set the variable as follows in your
                    <filename>local.conf</filename> file:
                    <literallayout class='monospaced'>
     USERADD_GID_TABLES = "files/group"
                    </literallayout>
                </para>

                <note>
                    Setting the
                    <link linkend='var-USERADDEXTENSION'><filename>USERADDEXTENSION</filename></link>
                    variable to "useradd-staticids" causes the build system
                    to use static <filename>gid</filename> values.
                </note>
            </glossdef>
        </glossentry>

        <glossentry id='var-USERADD_UID_TABLES'><glossterm>USERADD_UID_TABLES</glossterm>
            <glossdef>
                <para>
                    Specifies a password file to use for obtaining static
                    user identification (<filename>uid</filename>) values
                    when the OpenEmbedded build system adds a user to the
                    system during package installation.
                </para>

                <para>
                    When applying static user identification
                    (<filename>uid</filename>) values, the OpenEmbedded build
                    system looks in
                    <link linkend='var-BBPATH'><filename>BBPATH</filename></link>
                    for a <filename>files/passwd</filename> file and then applies
                    those <filename>uid</filename> values.
                    Set the variable as follows in your
                    <filename>local.conf</filename> file:
                    <literallayout class='monospaced'>
     USERADD_UID_TABLES = "files/passwd"
                    </literallayout>
                </para>

                <note>
                    Setting the
                    <link linkend='var-USERADDEXTENSION'><filename>USERADDEXTENSION</filename></link>
                    variable to "useradd-staticids" causes the build system
                    to use static <filename>uid</filename> values.
                </note>
            </glossdef>
        </glossentry>

        <glossentry id='var-USERADD_PACKAGES'><glossterm>USERADD_PACKAGES</glossterm>
            <glossdef>
                <para>
                    When inheriting the
                    <link linkend='ref-classes-useradd'><filename>useradd</filename></link>
                    class, this variable
                    specifies the individual packages within the recipe that
                    require users and/or groups to be added.
                </para>

                <para>
                    You must set this variable if the recipe inherits the
                    class.
                    For example, the following enables adding a user for the
                    main package in a recipe:
                    <literallayout class='monospaced'>
     USERADD_PACKAGES = "${PN}"
                    </literallayout>
                    <note>
                        If follows that if you are going to use the
                        <filename>USERADD_PACKAGES</filename> variable,
                        you need to set one or more of the
                        <link linkend='var-USERADD_PARAM'><filename>USERADD_PARAM</filename></link>,
                        <link linkend='var-GROUPADD_PARAM'><filename>GROUPADD_PARAM</filename></link>,
                        or
                        <link linkend='var-GROUPMEMS_PARAM'><filename>GROUPMEMS_PARAM</filename></link>
                        variables.
                    </note>
                </para>

            </glossdef>
        </glossentry>

        <glossentry id='var-USERADD_PARAM'><glossterm>USERADD_PARAM</glossterm>
            <glossdef>
                <para>
                    When inheriting the
                    <link linkend='ref-classes-useradd'><filename>useradd</filename></link>
                    class, this variable
                    specifies for a package what parameters should be passed
                    to the <filename>useradd</filename> command
                    if you wish to add a user to the system when the package
                    is installed.
                </para>

                <para>
                    Here is an example from the <filename>dbus</filename>
                    recipe:
                    <literallayout class='monospaced'>
     USERADD_PARAM_${PN} = "--system --home ${localstatedir}/lib/dbus \
                            --no-create-home --shell /bin/false \
                            --user-group messagebus"
                    </literallayout>
                    For information on the standard Linux shell command
                    <filename>useradd</filename>, see
                    <ulink url='http://linux.die.net/man/8/useradd'></ulink>.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-USERADDEXTENSION'><glossterm>USERADDEXTENSION</glossterm>
            <glossdef>
                <para>
                    When set to "useradd-staticids", causes the
                    OpenEmbedded build system to base all user and group
                    additions on a static
                    <filename>passwd</filename> and
                    <filename>group</filename> files found in
                    <link linkend='var-BBPATH'><filename>BBPATH</filename></link>.
                </para>

                <para>
                    To use static user identification (<filename>uid</filename>)
                    and group identification (<filename>gid</filename>)
                    values, set the variable
                    as follows in your <filename>local.conf</filename> file:
                    <literallayout class='monospaced'>
     USERADDEXTENSION = "useradd-staticids"
                    </literallayout>
                    <note>
                        Setting this variable to use static
                        <filename>uid</filename> and <filename>gid</filename>
                        values causes the OpenEmbedded build system to employ
                        the
                        <link linkend='ref-classes-useradd-staticids'><filename>useradd-staticids</filename></link>
                        class.
                    </note>
                </para>

                <para>
                    If you use static <filename>uid</filename> and
                    <filename>gid</filename> information, you must also
                    specify the <filename>files/passwd</filename> and
                    <filename>files/group</filename> files by setting the
                    <link linkend='var-USERADD_UID_TABLES'><filename>USERADD_UID_TABLES</filename></link>
                    and
                    <link linkend='var-USERADD_GID_TABLES'><filename>USERADD_GID_TABLES</filename></link>
                    variables.
                    Additionally, you should also set the
                    <link linkend='var-USERADD_ERROR_DYNAMIC'><filename>USERADD_ERROR_DYNAMIC</filename></link>
                    variable.
                </para>
            </glossdef>
        </glossentry>

    </glossdiv>

<!--            <glossdiv id='var-glossary-v'><title>V</title>-->
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    <glossdiv id='var-glossary-w'><title>W</title>

        <glossentry id='var-WARN_QA'><glossterm>WARN_QA</glossterm>
            <glossdef>
                <para>
                    Specifies the quality assurance checks whose failures are
                    reported as warnings by the OpenEmbedded build system.
                    You set this variable in your distribution configuration
                    file.
                    For a list of the checks you can control with this variable,
                    see the
                    "<link linkend='ref-classes-insane'><filename>insane.bbclass</filename></link>"
                    section.
                </para>
            </glossdef>
        </glossentry>

        <glossentry id='var-WORKDIR'><glossterm>WORKDIR</glossterm>
            <glossdef>
                <para>
                    The pathname of the work directory in which the OpenEmbedded
                    build system builds a recipe.
                    This directory is located within the
                    <link linkend='var-TMPDIR'><filename>TMPDIR</filename></link>
                    directory structure and is specific to the recipe being
                    built and the system for which it is being built.
                </para>

                <para>
                    The <filename>WORKDIR</filename> directory is defined as
                    follows:
                    <literallayout class='monospaced'>
     ${TMPDIR}/work/${MULTIMACH_TARGET_SYS}/${PN}/${EXTENDPE}${PV}-${PR}
                    </literallayout>
                    The actual directory depends on several things:
                    <itemizedlist>
                        <listitem><link linkend='var-TMPDIR'><filename>TMPDIR</filename></link>:
                            The top-level build output directory</listitem>
                        <listitem><link linkend='var-MULTIMACH_TARGET_SYS'><filename>MULTIMACH_TARGET_SYS</filename></link>:
                            The target system identifier</listitem>
                        <listitem><link linkend='var-PN'><filename>PN</filename></link>:
                            The recipe name</listitem>
                        <listitem><link linkend='var-EXTENDPE'><filename>EXTENDPE</filename></link>:
                            The epoch - (if
                            <link linkend='var-PE'><filename>PE</filename></link>
                            is not specified, which is usually the case for most
                            recipes, then <filename>EXTENDPE</filename> is blank)</listitem>
                        <listitem><link linkend='var-PV'><filename>PV</filename></link>:
                            The recipe version</listitem>
                        <listitem><link linkend='var-PR'><filename>PR</filename></link>:
                            The recipe revision</listitem>
                    </itemizedlist>
                </para>

                <para>
                    As an example, assume a Source Directory top-level folder
                    name <filename>poky</filename>, a default Build Directory at
                    <filename>poky/build</filename>, and a
                    <filename>qemux86-poky-linux</filename> machine target
                    system.
                    Furthermore, suppose your recipe is named
                    <filename>foo_1.3.0-r0.bb</filename>.
                    In this case, the work directory the build system uses to
                    build the package would be as follows:
                    <literallayout class='monospaced'>
     poky/build/tmp/work/qemux86-poky-linux/foo/1.3.0-r0
                    </literallayout>
                </para>
            </glossdef>
        </glossentry>

    </glossdiv>

<!--            <glossdiv id='var-glossary-x'><title>X</title>-->
<!--            </glossdiv>-->

<!--            <glossdiv id='var-glossary-y'><title>Y</title>-->
<!--            </glossdiv>-->

<!--            <glossdiv id='var-glossary-z'><title>Z</title>-->
<!--            </glossdiv>-->

</glossary>
</chapter>
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