Intel ARCHITECTURE IA-32 User Manual download pdf (Page 432)

100

101

9-58 Vol. 3A

PROCESSOR MANAGEMENT AND INITIALIZATION

If no unused update blocks are available and the above criteria are not met, the BIOS can over-

write update block(s) for a processor stepping that is no longer present in the system. This can

be done by scanning the update blocks and comparing the processor steppings, identified in the

MP Specification table, to the processor steppings that currently exist in the system.

Finally, before storing the proposed update in NVRAM, the BIOS must verify the authenticity

of the update via the mechanism described in Section 9.11.6, “Microcode Update Loader.” This

includes loading the update into the current processor, executing the CPUID instruction, reading

MSR 08Bh, and comparing a calculated value with the update revision in the proposed update

header for equality.

When performing the write update function, the BIOS must record the entire update, including

the header, the update data, and the extended processor signature table (if applicable). When

writing an update, the original contents may be overwritten, assuming the above criteria have

been met. It is the responsibility of the BIOS to ensure that more recent updates are not over-

written through the use of this BIOS call, and that only a single update exists within the NVRAM

for any processor stepping and platform ID.

Figure 9-8 and Figure 9-9 show the process the BIOS follows to choose an update block and

ensure the integrity of the data when it stores the new microcode update.

1 2 ... 427 428 429 430 431 432 433 434 435 436 437 ... 635 636

Comments to this Manuals

No comments

Intel ARCHITECTURE IA-32 User Manual Page 432

Comments to this Manuals

Related products and manuals for Processors Intel ARCHITECTURE IA-32