Re: [PATCH] perf,x86,p6: Add userspace RDPMC quirk for P6

[Vince Weaver]

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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