From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 100354 invoked by alias); 4 Oct 2016 18:07:04 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 100329 invoked by uid 89); 4 Oct 2016 18:07:03 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-4.5 required=5.0 tests=BAYES_00,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=brobeckeradacorecom, brobecker@adacore.com, shipping, customers X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Tue, 04 Oct 2016 18:06:53 +0000 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 6CF908E697; Tue, 4 Oct 2016 18:06:52 +0000 (UTC) Received: from [127.0.0.1] (ovpn01.gateway.prod.ext.ams2.redhat.com [10.39.146.11]) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u94I6pqS001786; Tue, 4 Oct 2016 14:06:51 -0400 Subject: Re: [RFC/RFA] Add support for the --readnever command-line option (DWARF only) To: Yao Qi , Joel Brobecker References: <1467838463-15786-1-git-send-email-brobecker@adacore.com> Cc: "gdb-patches@sourceware.org" From: Pedro Alves Message-ID: Date: Tue, 04 Oct 2016 18:07:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-SW-Source: 2016-10/txt/msg00056.txt.bz2 On 07/12/2016 03:27 PM, Yao Qi wrote: > Hi Joel, > > On Wed, Jul 6, 2016 at 9:54 PM, Joel Brobecker wrote: >> Hello, >> >> One of our customers asked us about this option, which they could >> see as being available in the version of GDB shipped by RedHat but >> not in the version that AdaCore supports. >> >> The purpose of this option is to turn the load of debugging information >> off. The implementation proposed here is mostly a copy of the patch >> distributed with RedHat Fedora, and looking at the patch itself and >> the history, I can see some reasons why it was never submitted: > > Andrew Cagney posted the patch > https://www.sourceware.org/ml/gdb/2004-11/msg00216.html > >> - The patch appears to have been introduced as a workaround, at >> least initially; >> - The patch is far from perfect, as it simply shunts the load of >> DWARF debugging information, without really worrying about the >> other debug format. >> - Who really does non-symbolic debugging anyways? > > The reason, IMO, it was posted is that people want GDB avoid reading > debug info and efficiently dump stack backtrace. I think Red Hat people > must know why Fedora is shipping this patch. > > I don't object to this approach. > This predates my gdb involvement, I don't really know the history. Maybe Jan knows. In any case, I don't object to the approach. Is this skipping _unwind_ info as well though? I think the documentation should be clear on that, because if it does skip dwarf info for unwinding as well, then you may get a faster, but incorrect backtrace. Thanks, Pedro Alves