Re: [PATCH 1/1] perf/x86/intel: Add extended event constraints for Knights Landing

[Peter Zijlstra]

On Mon, Jun 20, 2016 at 10:26:30AM +0000, Odzioba, Lukasz wrote:
> On 08.06.2016 Peter Zijlstra wrote:
> > How does this work in the light of intel_alt_er() ?
> 
> Hi Peter,
> 
> If the constrained bit is valid on only one of the OCR MSRs (like in case of KNL), 
> then OCR valid mask will forbid altering it by the other MSR in intel_alt_er.

Yes, that is the intent, but how is this achieved? I'm not sure I see
how the patch ensure this.

Also, intel_get_event_constraints() has a path where it copies the
constraint, should it not also copy the new field?