Intel 64 and IA-32 Architectures Software Developers Manual Volume 2A, Instruction Set Reference, A-M

Vol. 2 3-169

INSTRUCTION SET REFERENCE, A-M

IA32_BIOS_SIGN_ID Returns Microcode Update Signature

For processors that support the microcode update facility, the IA32_BIOS_SIGN_ID

MSR is loaded with the update signature whenever CPUID executes. The signature is

returned in the upper DWORD. For details, see Chapter 9 in the Intel® 64 and IA-32

Architectures Software Developer’s Manual, Volume 3A.

INPUT EAX = 1: Returns Model, Family, Stepping Information

When CPUID executes with EAX set to 1, version information is returned in EAX (see

Figure 3-5). For example: model, family, and processor type for the Intel Xeon

processor 5100 series is as follows:

• Model — 1111B

• Family — 0101B

• Processor Type — 00B

See Table 3-14 for available processor type values. Stepping IDs are provided as

needed.

Figure 3-5. Version Information Returned by CPUID in EAX

OM16525

Processor Type

034781112131415161920272831

EAX

Family (0FH for the Pentium 4 Processor Family)

Model

Extended

Family ID

Extended

Model ID

Family

Model

Stepping

Extended Family ID (0)

Extended Model ID (0)

Reserved