Re: [PATCH v0 04/71] itrace: Infrastructure for instruction flowtracing units

[Peter Zijlstra]

On Tue, Jan 07, 2014 at 04:42:55PM +0100, Andi Kleen wrote:
> > Yes; go read this:
> > 
> >  lkml.kernel.org/r/20131219125205.GT3694@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> 
> Hmm, but AFAIK we're not using freeze counters on PMI today.
> We just rely on the explicit disabling in the counters through the global
> ctrl.
> 
> So it should be the same as with any other PMI which also does not
> automatically freeze. Not true?

Regardless whether its used or not; I'd very much like that answered.

> Or do you mean interaction with the LBRs here?
> (currently LBRs and PT are mutually exclusive)

Yes we very much rely on the FREEZE bits for LBR. PT and LBR being
mutually exclusive wasn't documented (or I missed it) and completely
blows.
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