From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263650AbTEEQxV (ORCPT ); Mon, 5 May 2003 12:53:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263693AbTEEQxQ (ORCPT ); Mon, 5 May 2003 12:53:16 -0400 Received: from adsl-66-127-195-58.dsl.snfc21.pacbell.net ([66.127.195.58]:4812 "EHLO panda.mostang.com") by vger.kernel.org with ESMTP id S263650AbTEEQvy (ORCPT ); Mon, 5 May 2003 12:51:54 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <16054.38799.132644.16835@panda.mostang.com> Date: Mon, 5 May 2003 09:55:43 -0700 To: Richard Henderson Cc: David.Mosberger@acm.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] fix vsyscall unwind information In-Reply-To: <20030505163444.GB9342@twiddle.net> References: <20030502004014$08e2@gated-at.bofh.it> <20030503210015$292c@gated-at.bofh.it> <20030504063010$279f@gated-at.bofh.it> <20030505074248.GA7812@twiddle.net> <16054.32214.804891.702812@panda.mostang.com> <20030505163444.GB9342@twiddle.net> X-Mailer: VM 7.03 under Emacs 21.2.1 Reply-To: David.Mosberger@acm.org X-URL: http://www.mostang.com/~davidm/ From: davidm@mostang.com (David Mosberger-Tang) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org >>>>> On Mon, 5 May 2003 09:34:44 -0700, Richard Henderson said: Richard> On Mon, May 05, 2003 at 08:05:58AM -0700, David Richard> Mosberger-Tang wrote: Why? Certainly it isn't needed for Richard> x86. >> Certain applications (such as debuggers) want to know. Sure, >> you can do symbol matching (if you have the symbol table) or >> code-reading (assuming you know the exact sigreturn sequence), >> but having a marker would be more reliable and faster. Richard> Eh. The whole point was to *eliminate* the special cases. Signal handlers have special significance on UNIX-like operating systems. An application might want to know when it's in a signal frame. If it's a problem to do this with DWARF2 info, fine. If not, please consider adding a marker (my current version of libunwind for x86 does code-reading to detect signal-frames; not pretty, but it works reasonable well in practice; it would be nicer to get rid of the code-reading though, in the future). --david