The Intel Embedded Graphics Suite (IEGS = VBIOS + Graphics driver) provides the ability to dedicate additional memory for graphics functions on the Microsoft Windows* Embedded Compact 7 platform. This is known as reserved memory. Firmware selects the amount of reserved memory. The reservation size is passed to the graphics driver through a scratch register available on the GMCH. Reserved memory helps minimize the amount of memory stolen from the OS for memory-limited, embedded systems. For instance, if firmware uses a 640 x 480, 32-bit framebuffer, a total of 1.2 MB is required. Stolen memory would need to be configured as 8 MB or higher, since the next smaller option is only 1 MB, too small for the 640 x 480, 32-bit framebuffer. In such a case, stolen memory can be programmed to 1 MB. Reserved memory can provide the additional memory required for the framebuffer, removing only a minimum amount of memory from the OS.
Note: Reserved memory is only available on the Microsoft Windows Embedded Compact 7 operating system, and must be accounted for in the config.bib memory layout file.
Additionally, one can configure the Microsoft Windows Embedded Compact 7 display driver for either static or dynamic allocation of video memory. The static model preallocates physical memory for the display driver and provides a more efficient surface allocation scheme. The dynamic model allocates surface memory on demand from the system and will incur a small performance hit. However, the dynamic model has the advantage of deallocation of video memory when not required, thus making it available to other applications.
The static memory model requires a base and size specification registered in the project.reg file. The base + size must reach to top of memory (TOM). Since this is not required to be specified in the config.bib memory map, care must be taken not to overlap any other memory arenas with the static allocation. See Defining Graphics Memory Size for further details on how to configure the static memory model.
The figure Typical Memory Map Using Static Memory Model shows a typical memory map, using a static memory model.
Typical Memory Map Using Static Memory Model
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