Re: perf hw in kexeced kernel broken in tip

[Cyrill Gorcunov]

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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