
System Address Map
R
4.2.1AGP DRAM Graphics Aperture
Accesses within the aperture range are forwarded to the system memory subsystem. The MCH translates the originally issued addresses via a translation table maintained in system memory. The aperture range should be programmed as
Note:
4.3System Management Mode (SMM) Memory Range
The MCH supports the use of system memory as System Management RAM (SMRAM) enabling the use of System Management Mode. The MCH supports three SMRAM options: Compatible SMRAM (C_SMRAM), High Segment (HSEG), and Top of Memory Segment (TSEG). System Management RAM (SMRAM) space provides a memory area that is available for the SMI handler’s 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 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
SMRAM.
•Optional larger
Note: Masters from the hub interface and AGP are not allowed to access the SMM space.
Intel® 82845 MCH for SDR Datasheet | 103 |