Specifications

34 Product Errata
25759 Rev. 3.79 July 2009
Revision Guide for AMD Athlon™ 64 and AMD Opteron™ Processors
70 Microcode Patch Loading in 64-bit Mode Fails To Use EDX
Description
When the PATCH_LOADER register (MSR C001_0020h) is written during the installation of a
microcode patch in 64-bit mode, the linear address of the patch should be formed by the
concatenation of EDX and EAX. The processor incorrectly uses RAX for this operation.
Note that patch loading in 32-bit mode is not affected by this erratum.
Potential Effect on System
The microcode patch fails to load.
Suggested Workaround
In 64-bit mode, limit the linear addresses used for microcode patch installations to 32 bits or less.
Fix Planned
Yes