Intel IA-32 Manual do Utilizador descarregar pdf (Página 415)

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Vol. 3A 9-41

PROCESSOR MANAGEMENT AND INITIALIZATION

9.11.3 Processor Identification

Each microcode update is designed to for a specific processor or set of processors. To determine

the correct microcode update to load, software must ensure that one of the processor signatures

embedded in the microcode update matches the 32-bit processor signature returned by the

CPUID instruction when executed by the target processor with EAX = 1. Attempting to load a

microcode update that does not match a processor signature embedded in the microcode update

with the processor signature returned by CPUID will cause the processor to reject the update.

Example 9-5 shows how to check for a valid processor signature match between the processor

and microcode update.

Example 9-5. Pseudo Code to Validate the Processor Signature

ProcessorSignature ← CPUID(1):EAX

If (Update.HeaderVersion == 00000001h)

{

// first check the ProcessorSignature field

If (ProcessorSignature == Update.ProcessorSignature)

Success

// if extended signature is present

Else If (Update.TotalSize > (Update.DataSize + 48))

{

// Assume the Data Size has been used to calculate the

// location of Update.ProcessorSignature[0].

For (N ← 0; ((N < Update.ExtendedSignatureCount) AND

(ProcessorSignature != Update.ProcessorSignature[N])); N++);

// if the loops ended when the iteration count is

// less than the number of processor signatures in

// the table, we have a match

If (N < Update.ExtendedSignatureCount)

Success

Else

Fail

}

Else

Fail

Else

Fail

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