Processor Configuration Registers
B/D/F/Type:
Address Offset:
Reset Value:
Access:
0/0/0/PCI
50–51h
0028h
RW-L, RW-KL
16 bits
Size:
BIOS Optimal Default
00h
Reset
Value
RST/
PWR
Bit
Access
Description
GTT Graphics Memory Size (GGMS)
This field is used to select the amount of Main Memory that is
pre-allocated to support the Internal Graphics Translation Table.
The BIOS ensures that memory is pre-allocated only when
Internal graphics is enabled.
GSM is assumed to be a contiguous physical DRAM space with
DSM, and BIOS needs to allocate a contiguous memory chunk.
Hardware will derive the base of GSM from DSM only using the
GSM size programmed in the register.
9:8
RW-L
0h
Uncore
Hardware functionality in case of programming this value to
Reserved is not ensured.
0h = No Preallocated Memory
1h = 1 MB of Preallocated Memory
2h = 2 MB of Preallocated Memory
3h = Reserved
Graphics Mode Select (GMS)
This field is used to select the amount of Main Memory that is
pre-allocated to support the Internal Graphics device in VGA
(non-linear) and Native (linear) modes. The BIOS ensures that
memory is pre-allocated only when Internal graphics is enabled.
This register is also Intel TXT lockable.
Hardware does not clear or set any of these bits automatically
based on IGD being disabled/enabled.
BIOS Requirement: BIOS must not set this field to 0h if IVD
(bit 1 of this register) is 0.
Note: It is recommended that the 1 GB pre-allocated memory
option be used for systems with at least 2 GB physical
DRAM.
Encodings are as follows:
0h = 0 MB
1h = 32 MB
7:3
RW-L
05h
Uncore
2h = 64 MB
3h = 96 MB
4h = 128 MB
5h = 160 MB
6h = 192 MB
7h = 224 MB
8h = 256 MB
9h = 288 MB
Ah = 320 MB
Bh = 352 MB
Ch = 384 MB
Dh = 416 MB
Eh = 448 MB
Fh = 480 MB
10h = 512 MB
11h = 1 GB
Other = Reserved
56
Datasheet, Volume 2
INTEL [ INTEL ]
