82830MP Datasheet, PDF (71/159 Pages) Intel Corporation – Intel 830MP Chipset: 82830MP Graphics and Memory Controller Hub (GMCH-M)

Intel^® 830MP Chipset
R
4.5.1.25
ESMRAMC - Extended System Management RAM Control Register -
Device #0
Address Offset:
Default Value:
Access:
Size:
91h
38h
Read/Write
8 bits
The Extended SMRAM register controls the configuration of Extended SMRAM space. The Extended
SMRAM (E_SMRAM) memory provides a write-back cacheable SMRAM memory space that is above
1 MB.
Bit
Description
7
H_SMRAM_EN (H_SMRAME): Controls the SMM memory space location (i.e. above 1 MB or below
1MB) When G_SMRAME is 1 and H_SMRAME this bit is set to 1, the high SMRAM memory space is
enabled. SMRAM accesses from 0FEDA0000h to 0FEDBFFFFh are remapped to SDRAM address
000A0000h to 000BFFFFh.
Once D_LCK is set, this bit becomes read only.
Default Value=0.
6
E_SMRAM_ERR (E_SMERR): This bit is set when CPU accesses the defined memory ranges in
Extended SMRAM (High Memory and T-segment) while not in SMM space and with the D-OPEN bit = 0.
It is software’s responsibility to clear this bit. The software must write a 1 to this bit to clear it
Default Value=0.
5
SMRAM_Cache (SM_CACHE): This bit is forced to ‘1’ by the GMCH-M .
Default Value=1.
4
SMRAM_L1_EN (SM_L1): This bit is forced to ‘1’ by the GMCH-M.
Default Value=1.
3
SMRAM_L2_EN (SM_L2): This bit is forced to ‘1’ by the GMCH-M.
Default Value=1.
2
Reserved
1
TSEG_SZ(T_SZ): Selects the size of the TSEG memory block if enabled. This memory is taken from
the top of SDRAM space (i.e. TOM - TSEG_SZ), which is no longer claimed by the memory controller.
This field decodes as follows:
TSEG_SZ Description
0
(TOM-512K) to TOM
1
(TOM-1M) to TOM
Once D_LCK is set, this bit becomes read only.
Default Value=0.
0
TSEG_EN (T_EN): Enabling of SMRAM memory (TSEG, 512 Kbytes or 1 Mbytes of additional SMRAM
memory) for Extended SMRAM space only. When G_SMRAME =1 and TSEG_EN = 1, the TSEG is
enabled to appear in the appropriate physical address space.
Once D_LCK is set, this bit becomes read only.
Default Value=0.
298338-001
Datasheet
71