Re: [PATCH] x86: Clean up files of Intel Processor Trace

[Peter Zijlstra <peterz@infradead.org>]

On Mon, Aug 03, 2015 at 12:03:13PM +0300, Alexander Shishkin wrote:
> Takao Indoh <indou.takao@jp.fujitsu.com> writes:

> Even though TOPA_SHIFT happens to be the same as PAGE_SHIFT, it is a
> property of a separate hardware block, not mmu. PAGE_SHIFT is 12, but
> 12 is not always PAGE_SHIFT.

PAGE_SHIFT is _always_ 12 on x86. Changing that will require changing
the page table format, a rather unlikely thing to go happen.

> > diff --git a/arch/x86/kernel/cpu/perf_event_intel_pt.c b/arch/x86/kernel/cpu/perf_event_intel_pt.c
> > index 183de71..1e7d89e 100644
> > --- a/arch/x86/kernel/cpu/perf_event_intel_pt.c
> > +++ b/arch/x86/kernel/cpu/perf_event_intel_pt.c
> > @@ -37,9 +37,9 @@ static struct pt_pmu pt_pmu;
> >  
> >  enum cpuid_regs {
> >  	CR_EAX = 0,
> > +	CR_EBX,
> >  	CR_ECX,
> > -	CR_EDX,
> > -	CR_EBX
> > +	CR_EDX
> >  };
> 
> This doesn't seem necessary.

For those of us suffering OCDs and all, its a good change though. The
alfabet song does go: A, B, C, D etc.. after all. Not: A, C, D, B ...