Specifications

Product Errata 63
Revision Guide for AMD Athlon™ 64 and AMD Opteron™ Processors
25759 Rev. 3.79 July 2009
103 AAM or DIV followed by AAM May Produce Incorrect Results
Description
An AAM (ASCII Adjust after Multiply) or DIV instruction followed closely by an AAM instruction
may interfere with each other. This erratum can only occur under a highly specific set of pipeline
conditions when AAM is followed by another AAM within 3 instructions, or DIV is followed by
AAM within 6 instructions. Either the first instruction (AAM or DIV) or the second instruction
(AAM) may produce incorrect results.
Potential Effect on System
Incorrect results may be produced. For the recommended usage of AAM, see section 3.3.3 of the
AMD64 Architecture Programmer's Manual Volume 1: Application Programming, order# 24592.
Suggested Workaround
This scenario was contrived in a highly randomized simulation environment and is not expected to
occur in a real system. In the unlikely event that the erratum is observed, add NOP instructions to
observe the instruction spacing given above.
Fix Planned
Yes