31:28

0h

RO

Reserved

27

0h

RW/L

PCIe Link Width Up-config Disable (PELWUD)

0: Link width upconfig is supported. The Processor advertises upconfig capability using the data rate symbol in its TS2 training ordered sets during Configuration.Complete. The CPU responds to link width upconfigs initiated by the downstream device.
1: Link width upconfig is NOT supported. The Processor does not advertise upconfig capability using the data rate field in TS2 training ordered sets during Configuration.Complete. The CPU does not respond to link width upconfigs initiated by the downstream device.

26

0h

RO

Reserved

25

0h

RW/L

DRAM ECC Disable (ECCDIS)

0: ECC is supported
1: ECC is not supported

24

0h

RW/L

Force DRAM ECC Enable (FDEE)

0: DRAM ECC optional via software.
1: DRAM ECC enabled. MCHBAR C0MISCCTL bit [0] and C1MISCCTL bit [0] are forced to 1 and Read-Only.
Note that FDEE and ECCDIS must not both be set to 1.

23

0h

RW/L

VT-d Disable (VTDD)

0: VT-d is supported
1: VT-d is not supported

22:21

0h

RO

Reserved

20:19

0h

RW/L

DRAM Maximum Size per Channel (DDRSZ)

This field defines the maximum allowed memory size per channel.

• 0: Unlimited (64GB per channel)
  
• 1: Maximum 8GB per channel
  
• 2: Maximum 4GB per channel
  
• 3: Maximum 2GB per channel
  

18

0h

RO

Reserved

17

0h

RW/L

DRAM 1N Timing Disable (D1NM)

0: Part is capable of supporting 1n mode timings on the DDR interface.
1: Part is not capable of supporting 1n mode. Only supported timings are 2n or greater.

16

0h

RO

Reserved

15

0h

RW/L

DTT Device Disable (CDD)

0: DTT Device enabled.
1: DTT Device disabled.

14

0h

RW/L

2 DIMMs Per Channel Enable (DDPCD)

Allows Dual Channel operation but only supports 1 DIMM per channel.
0: 2 DIMMs per channel enabled
1: 2 DIMMs per channel disabled.
This setting hardwires bits 2 and 3 of the rank population field for each channel to zero. (MCHBAR offset 260h, bits 22-23 for channel 0 and MCHBAR offset 660h, bits 22-23 for channel 1)

13

0h

RW/L

X2APIC Enable (X2APIC_​EN)

Extended Interrupt Mode.
0b: Hardware does not support Extended APIC mode.
1b: Hardware supports Extended APIC mode.

12

0h

RW/L

Dual Memory Channel Support (PDCD)

0: Capable of Dual Channel
1: Not Capable of Dual Channel - only single channel capable.

11

0h

RW/L

Internal Graphics Disable (IGD)

0: There is a graphics engine within this CPU. Internal Graphics Device (Device 2) is enabled and all of its memory and I/O spaces are accessible. Configuration cycles to Device 2 will be completed within the CPU. All non-SMM memory and IO accesses to VGA will be handled based on Memory and IO enables of Device 2 and IO registers within Device 2 and VGA Enable of the PCI to PCI bridge control register in Devices 1 and 6 (If PCI Express GFX attach is supported). A selected amount of Graphics Memory space is pre-allocated from the main memory based on Graphics Mode Select (GMS in the GGC Register). Graphics Memory is pre-allocated above TSEG Memory.
1: There is no graphics engine within this CPU. Internal Graphics Device (Device 2) and all of its memory and I/O functions are disabled. Configuration cycle targeted to Device 2 will be passed on to DMI. In addition, all clocks to internal graphics logic are turned off. All non-SMM memory and IO accesses to VGA will be handled based on VGA Enable of the PCI to PCI bridge control register in Devices 1 and 6. DEVEN [4:3] (Device 0, offset 54h) have no meaning. Device 2 Functions 0 and 1 are disabled and hidden.

10

0h

RW/L

DID0 Override Enable (DID0OE)

0: Disable ability to override DID0 - For production
1: Enable ability to override DID - For debug and samples only

9

0h

RO

Reserved

8

0h

RW/L

2 Level Memory Support (2LM_​SUPPORTED)

0: 2 Level Memory (2LM) is not supported. Only 1LM is supported.
1: 2 Level Memory (2LM) is supported

7:4

0h

RW/L

Compatibility Revision ID (CRID)

Compatibility Revision ID

3

0h

RW/L

Memory Overclocking (DDR_​OVERCLOCK)

Memory Overclocking support
0: Memory Overclocking is not supported
1: Memory Overclocking is supported

2:0

0h

RO

Reserved