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Subject: Re: perf hw  in kexeced kernel broken in tip
From: Peter Zijlstra <peterz@infradead.org>
To: Yinghai Lu <yinghai@kernel.org>
Cc: Don Zickus <dzickus@redhat.com>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        Vivek Goyal <vgoyal@redhat.com>, Ingo Molnar <mingo@elte.hu>,
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        Haren Myneni <hbabu@us.ibm.com>
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Date: Wed, 08 Dec 2010 11:39:53 +0100
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On Tue, 2010-12-07 at 16:26 -0800, Yinghai Lu wrote:
> > +++ b/arch/x86/kernel/cpu/perf_event.c
> > @@ -377,10 +377,10 @@ static bool check_hw_exists(void)
> >       u64 val, val_new = 0;
> >       int ret = 0;
> >  
> > -     val = 0xabcdUL;
> > -     ret |= checking_wrmsrl(x86_pmu.perfctr, val);
> > -     ret |= rdmsrl_safe(x86_pmu.perfctr, &val_new);
> > -     if (ret || val != val_new)
> > +     val = 0xabUL;
> > +     ret |= checking_wrmsrl(x86_pmu.eventsel, val);
> > +     ret |= rdmsrl_safe(x86_pmu.eventsel, &val_new);
> > +     if (ret || val != (val_new & 0xFF))
> >               return false;
> >  
> >       return true;
> 
> Thanks. it fixes the problem.
> 
Won't merge it though, I think it stinks..