linux-kernel - Re: [PATCH 3/6] x86: Allow the user not to build hw

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Message-ID: <20110503231241.GG2678@nowhere>
Date:	Wed, 4 May 2011 01:12:43 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	LKML <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Jason Wessel <jason.wessel@...driver.com>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 3/6] x86: Allow the user not to build hw_breakpoints

On Tue, May 03, 2011 at 08:35:53AM -0700, H. Peter Anvin wrote:
> On 04/27/2011 12:50 PM, Frederic Weisbecker wrote:
> > On Wed, Apr 27, 2011 at 11:54:17AM -0700, H. Peter Anvin wrote:
> >> Why do you have to be able to disable breakpoints to disable perf? That seems seriously backwards, especially since we had breakpoints long before perf...
> > 
> > That started when we implemented breakpoints as counters. Then we realized that
> > ptrace had its own scheduling that was somehow duplicating what perf was doing.
> > So we have finally unified that under perf. The good point is that archs don't need
> > to care much about ptrace breakpoints tracking, just the interface.
> > 
> > But yeah the bad point is that dependency.
> 
> It really is very bad... without breakpoints, you lose almost all
> debugging support.

Right, so it should be fine for embedded environment to disable breakpoints.
It depends on CONFIG_EXPERT now.
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