82G33 datasheet(67/437 Pages) INTEL

67 / 437 page

System Address Map

Datasheet

3.7

Graphics Memory Address Ranges (Intel® 82Q35,

82Q33, and 82G33 (G)MCH Only)

The (G)MCH can be programmed to direct memory accesses to IGD when addresses

are within any of five ranges specified via registers in (G)MCH’s Device 2 configuration

space.

• The Memory Map Base Register (MMADR) is used to access graphics control

registers.

• The Graphics Memory Aperture Base Register (GMADR) is used to access graphics

memory allocated via the graphics translation table.

• The Graphics Translation Table Base Register (GTTADR) is used to access the

translation table.

These ranges can reside above the Top-of-Low-DRAM and below High BIOS and APIC

address ranges. They MUST reside above the top of memory (TOLUD) and below 4 GB

so they do not steal any physical DRAM memory space.

GMADR is a Prefetchable range in order to apply USWC attribute (from the processor

point of view) to that range. The USWC attribute is used by the processor for write

combining.

3.8

System Management Mode (SMM)

System Management Mode uses main memory for System Management RAM (SMM

RAM). The (G)MCH supports: Compatible SMRAM (C_SMRAM), High Segment (HSEG),

and Top of Memory Segment (TSEG). System Management RAM space provides a

memory area that is available for the SMI handlers and code and data storage. This

memory resource is normally hidden from the system OS so that the processor has

immediate access to this memory space upon entry to SMM. The (G)MCH provides

three SMRAM options:

• Below 1 MB option that supports compatible SMI handlers.

• Above 1 MB option that allows new SMI handlers to execute with write-back

cacheable SMRAM.

• Optional TSEG area of 1 MB, 2 MB, or 8 MB in size. For the 82Q35/82Q33/82G33,

the TSEG area lies below IGD stolen memory.

The above 1 MB solutions require changes to compatible SMRAM handlers code to

properly execute above 1 MB.

Note: DMI Interface and PCI Express masters are not allowed to access the SMM space.

82G33 Datasheet(PDF) 67 Page - Intel Corporation