Management Engine Registers

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Management Engine Registers

The two main registers that are used by the Management Engine for memory are ME_SEGBASE and ME_SEGMASK. These two registers specify information about the location off the ME’s ‘stolen’ memory. This stolen memory resides at the Top Of Memory and is 32MB.

Attributes List

R - Read
W - Write
RV - Reserved - Software must not modify these bits
L - Read/Write Lock - These bits can be read and written to until the 'lock' bit/register has been set
K - Read/Write Key - These bits control access to other bits

ME_SEGBASE

Bits Attributes Default Value Description
63:39 RV 0 Reserved
38:20 RWL Variable Base Address of ME SEG. Must be 4-MB aligned. This field is controlled by bit 10 of ME_SEGMASK register
19:0 RV 0 Reserved

ME_SEGMASK

Bits Attributes Default Value Description
63:39 RV 0 Reserved
38:20 RWL Variable This field must match the corresponding field in ME_SEGBASE for it to be a valid ME memory range. The last hex digit of this field als corresponds to the size of the ME memory region.
19:12 RV 0 Reserved
11 RWL 0 This bit indicates whether or not the ME stolen memory range is enabled
10 RWKL 0 When set this register prevents modifcation to the ME_SEGBASE and ME_SEGMASK registers until reboot.
9:0 RV 0 Reserved

Default Value for 38:20

For first gen i7's (870, etc)

1FFFFh

For 2nd, 3rd, 4th gen i7 CPU’s. (2xxx, 3xxx, 4xxx)

7FFFFh

Register Location

For 1st gen i7 CPU’s. (850, etc)

ME_SEGBASE is located at PCI Device 8, Function 0, Offset 138h
ME_SEGMASK is located at PCI device 8, Function 0, offset 140h

For 2nd, 3rd, 4th gen i7 CPU’s. (2xxx, 3xxx, 4xxx)

ME_SEGBASE is located at PCI Device 0, Function 0, Offset 70h
ME_SEGMASK is located at PCI device 0, Function 0, offset 78h

Examples Of Registers Values After Boot

ASUSTeK Computer Inc. P8P67 Deluxe Motherboard [2nd gen i7]

ME_SEGBASE

00 00 80 FF 01 00 00 00

ME_SEGMASK

00 0C 80 FF 7F 00 00 00

Macbook Pro 8,2 Early 2011 [2nd gen i7]

ME_SEGBASE

00 00 80 FF 01 00 00 00

ME_SEGMASK

00 0C 80 FF 7F 00 00 00

ASUS Griffen z87 [4th gen i7]

ME_SEGBASE

00 00 00 FF 01 00 00 00

ME_SEGMASK =

00 0C 00 FF 7F 00 00 00

References

4th Generation i7.

http://www.intel.com/content/dam/www/public/us/en/documents/datasheets/4th-gen-core-family-desktop-vol-2-datasheet.pdf

3rd Generation i7.

http://www.intel.com/content/dam/www/public/us/en/documents/datasheets/3rd-gen-core-desktop-vol-2-datasheet.pdf

2nd Generation i7.

http://www.intel.com/content/dam/www/public/us/en/documents/datasheets/2nd-gen-core-desktop-vol-2-datasheet.pdf

1st Generation i7.

http://download.intel.com/design/processor/datashts/322165.pdf