Specifications

58 Product Errata
25759 Rev. 3.79 July 2009
Revision Guide for AMD Athlon™ 64 and AMD Opteron™ Processors
97 128-Bit Streaming Stores May Cause Coherency Failure
Description
Under a specific set of internal pipeline conditions, stale data may be left in the L1 cache when a 128-
bit streaming store (MOVNT*) to a writeback (WB) memory type misses in the L1 data cache and
both L1 and L2 TLBs.
Potential Effect on System
Memory coherence failures leading to unpredictable operation.
Suggested Workaround
BIOS should set DC_CFG.DIS_CNV_WC_SSO (bit 3 of MSR 0xC001_1022). The performance
effects of setting this bit are limited to streaming stores to the write-combining (WC) memory type, a
case expected to rarely occur in actual usage. No loss of performance occurs in the general case (WB
memory type).
This workaround must not be applied to processors prior to revision C0.
Fix Planned
Yes