AMD Athlon 6 - Manual (Page 8)

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AMD Athlon™ Processor Model 6 Revision Guide 24332G—October 2003
Preliminary Information
17 Deadlock May Occur in a Two-Processor System in the Presence of Probe to Memory-
Mapped I/O
Products Affected. A0, A2, A5
Normal Specified Operation. Processor should not hang.
Non-conformance. In a multiprocessor system, if one processor (A) is continuously writing to a cacheable
memory-mapped I/O block while the other processor (B) is trying to read the same cacheable I/O block,
and at the same time both processors are also trying to write a different memory-based cache block,
then processor B may hang. Should this occur and processor A fields an interrupt, the deadlock will be
resolved.
Potential Effect on System. System will hang or exhibit performance degradation.
Suggested Workaround. The current processor design assumes that memory-mapped I/O is incoherent and
does not handle all deadlock cases. System logic should not generate probes for memory mapped I/O
addresses.
Resolution Status. No fix planned.