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

Peter Zijlstra
2012-06-08T10:00:32Z

On Fri, 2012-06-08 at 11:35 +0200, Ingo Molnar wrote:
> * Peter Zijlstra <peterz@infradead.org> wrote:
>
> > On Thu, 2012-06-07 at 12:48 +0200, Stephane Eranian wrote:
> > > >> The warning could also be done on boot. But the check has to be done
> > > >> when the event is created.
> > > >
> > > > Is this because of the ucode loader not having done its thing yet etc..?
> >
> > Ah, its because you can update ucode at runtime of course.
> >
> > A quick look at the ucode loader doesn't show it having a
> > notifier either, so then yeah we need to check on every event
> > creation :/
> >
> > Or we could put a hook in the ucode loader.
>
> I'd really suggest the latter - I doubt this will be our only
> ucode dependent quirk, going forward ...

Yeah, am in the middle of writing that..