Re: [PATCH] perf/x86: check ucode before disabling PEBS on SandyBridge

Stephane Eranian
2012-06-12T08:14:22Z

On Fri, Jun 8, 2012 at 4:25 PM, Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Fri, 2012-06-08 at 16:07 +0200, Stephane Eranian wrote:
> > > +static const u32 snb_ucode_rev = 0x28;
> > > +
> >
> > That needs to be a per CPU model value. It
> > is not the same for SNB vs. SNB-EP. On EP
> > it may even depends on stepping.
>
> Yeah, you said, easiest is removing the const and putting some
> assignments to the thing somewhere in our model switch.
>
> Do you know what values for what chip we should use?
>

Ok, so to close on this, I tried the 6/6/2012 ucode update on a few
SNB-EP systems.

I got two answers depending on the stepping:
C1 (stepping 6) -> 0x618
C2 (stepping 7) -> 0x70c

So we need to check x86_mask for stepping and adjust the value of
snb_ucode_rev accordingly for model 45.