Programmable Attribute Map 4 (PAM4_0_0_0_PCI) – Offset 84 - 1.3 - ID:767625 | 12th Generation Intel® Core™ Processors Datasheet Volume 2 of 2

12th Generation Intel® Core™ Processors Datasheet Volume 2 of 2

ID	Date	Version	Classification
767625	07/13/2023		Public

Programmable Attribute Map 4 (PAM4_0_0_0_PCI) – Offset 84

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. Cache-ability of these areas is controlled via the MTRR register in the core.
Two bits are used to specify memory attributes for each memory segment. These bits apply to host accesses to the PAM areas. These attributes are:
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.

Bit Range	Default	Access	Field Name and Description
7:6	0h	RO	Reserved
5:4	0x0	RW/L	(HIENABLE) This field controls the steering of read and write cycles that address the BIOS area from 0DC000h to 0DFFFFh. 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
1:0	0x0	RW/L	(LOENABLE) This field controls the steering of read and write cycles that address the BIOS area from 0D8000h to 0DBFFFh. 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.