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

Peter Zijlstra
2012-06-12T17:18:29Z

On Tue, 2012-06-12 at 19:17 +0200, Borislav Petkov wrote:
> On Tue, Jun 12, 2012 at 07:13:23PM +0200, Peter Zijlstra wrote:
> > > That's what I had in my original version.
> >
> > Right, but you really need to check all cpus, not just the one you
> > happen to run on or the boot cpu.
>
> Ok, the answer to that question is whether sandybridge can support mixed
> ucode revisions or not. If not, you only need to check the current cpu
> you're on.

But the ucode loader can be (ab)used to only update one of the many
CPUs.