From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 24508 invoked by alias); 30 Nov 2010 18:40:50 -0000 Received: (qmail 24395 invoked by uid 22791); 30 Nov 2010 18:40:49 -0000 X-SWARE-Spam-Status: No, hits=-4.7 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_HI,TW_KG,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Received: from smtp-outbound-1.vmware.com (HELO smtp-outbound-1.vmware.com) (65.115.85.69) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Tue, 30 Nov 2010 18:40:43 +0000 Received: from mailhost4.vmware.com (mailhost4.vmware.com [10.16.67.124]) by smtp-outbound-1.vmware.com (Postfix) with ESMTP id 0FFBB1E006; Tue, 30 Nov 2010 10:40:40 -0800 (PST) Received: from msnyder-server.eng.vmware.com (promd-2s-dhcp138.eng.vmware.com [10.20.124.138]) by mailhost4.vmware.com (Postfix) with ESMTP id EFB2CC9C56; Tue, 30 Nov 2010 10:40:39 -0800 (PST) Message-ID: <4CF54527.2070609@vmware.com> Date: Tue, 30 Nov 2010 18:40:00 -0000 From: Michael Snyder User-Agent: Thunderbird 2.0.0.24 (X11/20101103) MIME-Version: 1.0 To: =?UTF-8?B?QW3DqXJpY28gV2FuZw==?= CC: Mark Wielaard , Andi Kleen , Hui Zhu , "linux-kernel@vger.kernel.org" , "gdb@sourceware.org" , "hellogcc@freelists.org" Subject: Re: [PATCH] Built kernel without -O2 option References: <87r5e4lab7.fsf@basil.nowhere.org> <1291025536.2904.6.camel@springer.wildebeest.org> <20101130093106.GD5203@cr0.nay.redhat.com> In-Reply-To: <20101130093106.GD5203@cr0.nay.redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-IsSubscribed: yes Mailing-List: contact gdb-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sourceware.org X-SW-Source: 2010-11/txt/msg00134.txt.bz2 Américo Wang wrote: > On Mon, Nov 29, 2010 at 11:12:16AM +0100, Mark Wielaard wrote: >> On Mon, 2010-11-29 at 10:59 +0100, Andi Kleen wrote: >>> Hui Zhu writes: >>> >>>> Now, there are a lot of ways to debug the Linux kernel with GDB, like >>>> qemu, kgtp or kgdb and so on. >>>> But the developer more like add a printk. It have a lot of reason, a big one is: >>>> (gdb) p ret >>>> $3 = >>>> And the code execution order is not right. >>> Really the right place to fix a lot of this would be gcc (and perhaps >>> gdb). I suspect with some careful work the debugging experience >>> for -O2 could be improved a lot. >>> I also believe the latest gccs already have improvements in this area. >> The VTA branch was merged for GCC 4.5 >> http://gcc.gnu.org/wiki/Var_Tracking_Assignments >> Which helps a lot with generating dwarf for previously "optimized out" >> values. There were also a couple of papers on generating even better >> debuginfo at the recent GCC Summit: http://gcc.gnu.org/wiki/summit2010 >> >> Jakub Jelínek, Improving debug info for optimized away parameters >> http://gcc.gnu.org/wiki/summit2010?action=AttachFile&do=get&target=jelinek.pdf >> Alexandre Oliva, Consistent Views at Recommended Breakpoints >> http://gcc.gnu.org/wiki/summit2010?action=AttachFile&do=get&target=oliva.pdf >> > > Cool! It would be much more convenient if this is solved by gcc. Those features mentioned at the GCC summit are not real close to completion. I wouldn't put off the discussion just because they're (possibly) in the pipeline.