Messages in this thread | | | Date | Wed, 5 Feb 2014 15:04:03 -0500 (EST) | From | Vince Weaver <> | Subject | Re: [PATCH] perf,x86,p6: Add userspace RDPMC quirk for P6 |
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On Wed, 5 Feb 2014, Peter Zijlstra wrote:
> On Wed, Feb 05, 2014 at 02:37:29PM -0500, Vince Weaver wrote: > > On Wed, 5 Feb 2014, Vince Weaver wrote: > > > > > Has someone actually hit this bug? People used PAPI/perfctr on these > > > machines for years, and it uses rdpmc by default so I would think it would > > > show up if it were an issue. I should check the perfctr code to see if it > > > had some sort of check. > > > > I can verify the perfctr code does have a case for PPRO errata 26, but it > > only disables things on pentium pros with stepping less than 9. > > The doc said 0xB1, right? Should we keep it at that? Its not like > there's a lot of PPro machines left out there, so better safe than > sorry.
mfg steping "sB1" which means processor stepping 9. See page 15 of the document linked in the original patch.
I used to have a Pentium Pro that was apparently affected by this erratum but not any more. The oldest machine I test perf stuff on is a Pentium II.
Vince
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