Filter
Top Products
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 0 4 Version number of the update header.
Update Revision 4 4 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 8 4 Date of the update creation in binary format: mmddyyyy
(e.g. 07/18/98 is 07181998H).
Processor
Signature
12 4 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 16 4 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 20 4 Version number of the loader program needed to
correctly load this update. The initial version is
00000001H.
Processor Flags 24 4 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 28 4 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 32 4 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.