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From: Frederic Weisbecker <fweisbec@gmail.com>
To: Jiri Olsa <jolsa@redhat.com>,
	Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Cc: xiakaixu <xiakaixu@huawei.com>,
	linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
	paulus@samba.org, Ingo Molnar <mingo@kernel.org>,
	a.p.zijlstra@chello.nl,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Borislav Petkov <bp@alien8.de>,
	Namhyung Kim <namhyung@kernel.org>,
	Huxinwei <huxinwei@huawei.com>,
	peifeiyue@huawei.com
Subject: Re: Does perf support different length of user-space hw_breakpoint?
Date: Tue, 13 May 2014 17:06:15 +0200	[thread overview]
Message-ID: <20140513150613.GC13828@localhost.localdomain> (raw)
In-Reply-To: <20140513120046.GB1138@krava.brq.redhat.com>

On Tue, May 13, 2014 at 02:00:46PM +0200, Jiri Olsa wrote:
> On Mon, May 12, 2014 at 03:52:54PM +0800, xiakaixu wrote:
> > Hi guys,
> > 
> > Does perf support different length of user-space hw_breakpoint,
> > such as  HW_BREAKPOINT_LEN_1/HW_BREAKPOINT_LEN_2/HW_BREAKPOINT_LEN_4/
> > HW_BREAKPOINT_LEN_8?
> > 
> > Seems perf only support HW_BREAKPOINT_LEN_4/sizeof(long)
> > by default from the source code and simple test.
> 
> right..
> 
>         /*
>          * We should find a nice way to override the access length
>          * Provide some defaults for now
>          */
>         if (attr.bp_type == HW_BREAKPOINT_X)
>                 attr.bp_len = sizeof(long);
>         else
>                 attr.bp_len = HW_BREAKPOINT_LEN_4;
> 
> > 
> > May I have your opinions if I want to trace different bytes of
> > hw_breakpoint addr?
> 
> I guess that depends on what you want to do ;-)

Ah, I have a patchset from Jacob Shin and Suravee Suthikulpanit that does
that. Also it has been hanging around for too long by my fault. I'm posting
it now.

  reply	other threads:[~2014-05-13 15:06 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-05-12  7:52 Does perf support different length of user-space hw_breakpoint? xiakaixu
2014-05-12  8:05 ` Peter Zijlstra
     [not found]   ` <CAGjdHukwC3cu3YOSSteXsC4_52m-YTdAAYCfXV+q5A2pnW+CKQ@mail.gmail.com>
2014-05-12  8:48     ` Peter Zijlstra
2014-05-12  9:00       ` xiakaixu
2014-05-13 11:38         ` xiakaixu
2014-05-13 12:00 ` Jiri Olsa
2014-05-13 15:06   ` Frederic Weisbecker [this message]
2014-05-14  2:55     ` xiakaixu

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