Some new revelations in the "Processor Revision Guide," a.k.a., "bug list"
1. Three previously disclosed minor bugs continue unchanged because there are easy workarounds (these all have to do with hardware)
2. Four new bugs were discovered. One of these, #13, was fixed in the latest stepping, but sounds somewhat serious:
13 Instruction Execution Deadlock
Products Affected. A4, A5, A6, A7
Normal Specified Operation. Legitimate instruction sequences should execute as specified. [DUH!]
Non-conformance. Under rare and unlikely conditions, the load-store unit, instruction scheduler and effective address generation unit interact in such a way that deadlock a occurs, preventing further instruction execution.
Potential Effect on System. The system hangs. No instructions complete and the processor will not respond to interrupts.
Suggested Workaround. None.
Resolution Status. Fix planned for a future revision.
The current stepping is listed as A9, and a prior table also shows that this bug does not affect A9. A9 must be the AXIA core. Anyhow, this problem would not show up as Windows crashing with a blue screen or whatever, if it really happened the CPU would just plain stop running and require a reset.
Bug 14 is interesting - it says that processors with X-and-a-half multipliers could hang when reconnecting to the bus when coming out of two of the low power states. Fix is planned for a future revision
Bug 15 says that the microcode patch capability does not work yet. This is something new in the AXIA stepping -- there is apparently a little bit of RAM that can be loaded with microcode patches. But the suggested workaround is "Do not load a microcode patch." Fix is planned for a future revision.
I had noticed previously that my motherboard reported Microcode Patch Level 0 when booting an AXIA TBird.
Bug 16 has a software workaround and seems pretty obscure. Maybe someone can comment on it.
The document also begs the question: "What happened to stepping A8? The current stepping is A9, and prior steppings include A4, A5, A6, A7.
Also, stepping A9 is the first one with a CPUID change, it is now 0644, prior steppings were 0642. Can someone confirm that 0644=AXIA?
The link to the pdf file is found after "AMD Athlon™ Processor Model 4 Revision Guide 23614F" on this page: amd.com
Petz |
