Intel 253668-032US Manuale Utente

9-38 Vol. 3

PROCESSOR MANAGEMENT AND INITIALIZATION

NOTE

The optional extended signature table is supported starting with
processor family 0FH, model 03H.

Table 9-6. Microcode Update Field Definitions

Field Name

Offset

(bytes)

Length

(bytes)

Description

Header Version

Version number of the update header.

Update Revision

Unique version number for the update, the basis for the

update signature provided by the processor to indicate

the current update functioning within the processor.

Used by the BIOS to authenticate the update and verify

that the processor loads successfully. The value in this

field cannot be used for processor stepping identification

alone. This is a signed 32-bit number.

Date

Date of the update creation in binary format: mmddyyyy

(e.g. 07/18/98 is 07181998H).

Processor

Signature

Extended family, extended model, type, family, model,

and stepping of processor that requires this particular

update revision (e.g., 00000650H). Each microcode

update is designed specifically for a given extended

family, extended model, type, family, model, and stepping

of the processor.

The BIOS uses the processor signature field in

conjunction with the CPUID instruction to determine

whether or not an update is appropriate to load on a

processor. The information encoded within this field

exactly corresponds to the bit representations returned

by the CPUID instruction.

Checksum

Checksum of Update Data and Header. Used to verify the

integrity of the update header and data. Checksum is

correct when the summation of all the DWORDs (including

the extended Processor Signature Table) that comprise

the microcode update result in 00000000H.

Loader Revision

Version number of the loader program needed to

correctly load this update. The initial version is

00000001H.

Processor Flags

Platform type information is encoded in the lower 8 bits

of this 4-byte field. Each bit represents a particular

platform type for a given CPUID. The BIOS uses the

processor flags field in conjunction with the platform Id

bits in MSR (17H) to determine whether or not an update

is appropriate to load on a processor. Multiple bits may be

set representing support for multiple platform IDs.

Data Size

Specifies the size of the encrypted data in bytes, and

must be a multiple of DWORDs. If this value is

00000000H, then the microcode update encrypted data

is 2000 bytes (or 500 DWORDs).

Total Size

Specifies the total size of the microcode update in bytes.

It is the summation of the header size, the encrypted

data size and the size of the optional extended signature

table. This value is always a multiple of 1024.