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SubjectRe: perf hw in kexeced kernel broken in tip
On Thu, Dec 09, 2010 at 03:20:08PM -0500, Don Zickus wrote:
...
>
> Getting closer...
>
> Pentium4s are special they need the double write, so...
>
> > + /*
> > + * Now write a value and read it back to see if it matches,
> > + * this is needed to detect certain hardware emulators (qemu/kvm)
> > + * that don't trap on the MSR access and always return 0s.
> > + */
> > val = 0xabcdUL;
> > - ret |= checking_wrmsrl(x86_pmu.perfctr, val);
> > + ret = checking_wrmsrl(x86_pmu.perfctr, val);
>
> if (x86_pmu.perfctr_second_write)
> ret |= checking_wrmsrl(x86_pmu.perfctr, val);
>
> solved my p4 problems for kexec.
>
...

yeah, thanks! would you push a patch upstream?

Cyrill


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