linux-kernel - Re: [PATCH 1/3] perf/x86/amd: AMD support for bp_len > HW_BREAKPOINT_LEN

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Message-ID: <20131109151156.GA14249@redhat.com>
Date:	Sat, 9 Nov 2013 16:11:56 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	suravee.suthikulpanit@....com, mingo@...nel.org, mingo@...hat.com,
	jacob.w.shin@...il.com, a.p.zijlstra@...llo.nl,
	acme@...stprotocols.net, hpa@...or.com, tgl@...ain.invalid,
	linux-kernel@...r.kernel.org, sherry.hurwitz@....com
Subject: Re: [PATCH 1/3] perf/x86/amd: AMD support for bp_len >
	HW_BREAKPOINT_LEN_8

On 11/08, Frederic Weisbecker wrote:
>
> On Wed, Oct 02, 2013 at 11:11:06AM -0500, suravee.suthikulpanit@....com wrote:
> >
> > diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
> > index d3f5c63..26609bb 100644
> > --- a/arch/x86/include/asm/cpufeature.h
> > +++ b/arch/x86/include/asm/cpufeature.h
> > @@ -170,6 +170,7 @@
> >  #define X86_FEATURE_TOPOEXT	(6*32+22) /* topology extensions CPUID leafs */
> >  #define X86_FEATURE_PERFCTR_CORE (6*32+23) /* core performance counter extensions */
> >  #define X86_FEATURE_PERFCTR_NB  (6*32+24) /* NB performance counter extensions */
> > +#define X86_FEATURE_BPEXT	(6*32+26) /* data breakpoint extension */
>
> Does this feature only work on data breakpoint or is instruction breakpoint
> address range supported as well?

IIRC, execute range is supported as well.

But. I can't look at the code now, but iirc this can't really work until
we fix the (already discussed) problems with bp_len && X86_BREAKPOINT_LEN_X.
IOW, we should not blame these patches if it doesn't work.

Oleg.

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