Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753142Ab1ECPgV (ORCPT ); Tue, 3 May 2011 11:36:21 -0400 Received: from terminus.zytor.com ([198.137.202.10]:52169 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751435Ab1ECPgU (ORCPT ); Tue, 3 May 2011 11:36:20 -0400 Message-ID: <4DC020D9.3050000@zytor.com> Date: Tue, 03 May 2011 08:35:53 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.17) Gecko/20110428 Fedora/3.1.10-1.fc15 Thunderbird/3.1.10 MIME-Version: 1.0 To: Frederic Weisbecker CC: LKML , Ingo Molnar , Peter Zijlstra , Jason Wessel , Thomas Gleixner Subject: Re: [PATCH 3/6] x86: Allow the user not to build hw_breakpoints References: <1303923602-2923-1-git-send-email-fweisbec@gmail.com> <1303923602-2923-4-git-send-email-fweisbec@gmail.com> <4DB854AA.6070101@zytor.com> <20110427182633.GB1753@nowhere> <008d59a3-bd23-4cb3-8a73-1640137e3ac4@email.android.com> <20110427195004.GA3654@nowhere> In-Reply-To: <20110427195004.GA3654@nowhere> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1092 Lines: 25 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. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/