From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 18586 invoked by alias); 12 Dec 2006 15:21:09 -0000 Received: (qmail 18417 invoked by uid 22791); 12 Dec 2006 15:21:04 -0000 X-Spam-Check-By: sourceware.org Received: from mx1.redhat.com (HELO mx1.redhat.com) (66.187.233.31) by sourceware.org (qpsmtpd/0.31) with ESMTP; Tue, 12 Dec 2006 15:20:56 +0000 Received: from int-mx1.corp.redhat.com (int-mx1.corp.redhat.com [172.16.52.254]) by mx1.redhat.com (8.12.11.20060308/8.12.11) with ESMTP id kBCFKiF5007538; Tue, 12 Dec 2006 10:20:44 -0500 Received: from lacrosse.corp.redhat.com (lacrosse.corp.redhat.com [172.16.52.154]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id kBCFKfpW004836; Tue, 12 Dec 2006 10:20:41 -0500 Received: from [192.168.7.77] (vpn-14-38.rdu.redhat.com [10.11.14.38]) by lacrosse.corp.redhat.com (8.12.11.20060308/8.11.6) with ESMTP id kBCFKevM026497; Tue, 12 Dec 2006 10:20:40 -0500 Message-ID: <457EC8BF.3040707@redhat.com> Date: Tue, 12 Dec 2006 15:21:00 -0000 From: Ulrich Drepper User-Agent: Thunderbird 1.5.0.8 (X11/20061107) MIME-Version: 1.0 To: Andrew Haley CC: Mark Kettenis , Jan Kratochvil , gcc@gcc.gnu.org, libc-alpha@sources.redhat.com, gdb@sourceware.org, Jakub Jelinek , Richard Henderson Subject: Re: Unwinding CFI gcc practice of assumed `same value' regs References: <20061211190300.GA4372@host0.dyn.jankratochvil.net> <17790.46246.634400.638852@zebedee.pink> <22844.82.92.89.47.1165935102.squirrel@webmail.xs4all.nl> <17790.50417.668957.495292@zebedee.pink> In-Reply-To: <17790.50417.668957.495292@zebedee.pink> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 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: 2006-12/txt/msg00096.txt.bz2 Andrew Haley wrote: > Null-terminating the call stack is too well-established practice to be > changed now. Which does not mean that the mistake should hold people back. This is just one of the mistakes in the x86-64 ABI. It was copied from x86 and it was wrong there already. > In practice, %ebp either points to a call frame -- not necessarily the > most recent one -- or is null. I don't think that having an optional > frame pointer mees you can use %ebp for anything random at all, Of course it means that. > The right way to fix the ABI is to specify that %ebp mustn't be > [mis]used in this way, not to add a bunch more unwinder data. Nope. The right way is to specify things like backtraces with the adequate mechanism. I fully support adding the Dwarf3 unwinder requirements. -- ➧ Ulrich Drepper ➧ Red Hat, Inc. ➧ 444 Castro St ➧ Mountain View, CA ❖