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Vol. 3 9-39
PROCESSOR MANAGEMENT AND INITIALIZATION
Reserved 36 12 Reserved fields for future expansion
Update Data 48 Data Size or
2000
Update data
Extended Signature
Count
Data Size +
48
4 Specifies the number of extended signature structures
(Processor Signature[n], processor flags[n] and
checksum[n]) that exist in this microcode update.
Extended
Checksum
Data Size +
52
4 Checksum of update extended processor signature table.
Used to verify the integrity of the extended processor
signature table. Checksum is correct when the
summation of the DWORDs that comprise the extended
processor signature table results in 00000000H.
Reserved Data Size +
56
12 Reserved fields
Processor
Signature[n]
Data Size +
68 + (n * 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.
Processor Flags[n] Data Size +
72 + (n * 12)
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.
Checksum[n] Data Size +
76 + (n * 12)
4 Used by utility software to decompose a microcode
update into multiple microcode updates where each of
the new updates is constructed without the optional
Extended Processor Signature Table.
To calculate the Checksum, substitute the Primary
Processor Signature entry and the Processor Flags entry
with the corresponding Extended Patch entry. Delete the
Extended Processor Signature Table entries. The
Checksum is correct when the summation of all DWORDs
that comprise the created Extended Processor Patch
results in 00000000H.
Table 9-6. Microcode Update Field Definitions (Contd.)
Field Name Offset
(bytes)
Length
(bytes)
Description