Specification Sheet
Host Bridge/DRAM Registers
82 Datasheet, Volume 2 of 2
RE - Read Enable. When RE=1, the host read accesses to the corresponding memory
segment are claimed by the Uncore and directed to main memory. Conversely, when
RE=0, the host read accesses are directed to DMI.
WE - Write Enable. When WE=1, the host write accesses to the corresponding memory
segment are claimed by the Uncore and directed to main memory. Conversely, when
WE=0, the host read accesses are directed to DMI.
The RE and WE attributes permit a memory segment to be Read Only, Write Only,
Read/Write or Disabled. For example, if a memory segment has RE=1 and WE=0, the
segment is Read Only.
Access Method
Default: 0h
3.25 Programmable Attribute Map 4 (PAM4)—Offset
84h
This register controls the read, write and shadowing attributes of the BIOS range from
D8000h to DFFFFh. The Uncore allows programmable memory attributes on 13 legacy
memory segments of various sizes in the 768KB to 1MB address range. Seven
Programmable Attribute Map (PAM) registers are used to support these features.
Cacheability of these areas is controlled via the MTRR register in the core.
Type: CFG
(Size: 8 bits)
Offset: [B:0, D:0, F:0] + 83h
7 4 0
0 0 0 0 0 0 0 0
RSVD
HIENABLE
RSVD
LOENABLE
Bit
Range
Default &
Access
Field Name (ID): Description
7:6
0h
RO
Reserved (RSVD): Reserved.
5:4
0h
RW_L
HIENABLE: This field controls the steering of read and write cycles that address the
BIOS area from 0D4000h to 0D7FFFh.
00: DRAM Disabled. All accesses are directed to DMI.
01: Read Only. All reads are sent to DRAM, all writes are forwarded to DMI.
10: Write Only. All writes are sent to DRAM, all reads are serviced by DMI.
11: Normal DRAM Operation. All reads and writes are serviced by DRAM.
3:2
0h
RO
Reserved (RSVD): Reserved.
1:0
0h
RW_L
LOENABLE: This field controls the steering of read and write cycles that address the
BIOS area from 0D0000h to 0D3FFFh.
00: DRAM Disabled. All reads are sent to DRAM. All writes are forwarded to DMI.
01: Read Only. All reads are sent to DRAM. All writes are forwarded to DMI.
10: Write Only. All writes are sent to DRAM. All reads are serviced by DMI.
11: Normal DRAM Operation. All reads and writes are serviced by DRAM.