From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 18391 invoked by alias); 11 Jul 2005 17:52:31 -0000 Mailing-List: contact gdb-help@sources.redhat.com; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sources.redhat.com Received: (qmail 18313 invoked by uid 22791); 11 Jul 2005 17:52:21 -0000 Received: from norbert.ecoscentric.com (HELO smtp.ecoscentric.com) (194.153.168.165) by sourceware.org (qpsmtpd/0.30-dev) with ESMTP; Mon, 11 Jul 2005 17:52:21 +0000 Received: by smtp.ecoscentric.com (Postfix, from userid 99) id B9E0B65C082; Mon, 11 Jul 2005 18:52:19 +0100 (BST) Received: from [127.0.0.1] (localhost [127.0.0.1]) by smtp.ecoscentric.com (Postfix) with ESMTP id D230B65C07D; Mon, 11 Jul 2005 18:52:13 +0100 (BST) Message-ID: <42D2B1CD.2020605@eCosCentric.com> Date: Mon, 11 Jul 2005 17:52:00 -0000 From: Jonathan Larmour User-Agent: Mozilla Thunderbird 1.0.2-1.3.3 (X11/20050513) MIME-Version: 1.0 To: Daniel Jacobowitz Cc: gdb@sources.redhat.com Subject: Re: Thread backtrace termination References: <42D29C67.4070509@eCosCentric.com> <20050711162326.GA32686@nevyn.them.org> In-Reply-To: <20050711162326.GA32686@nevyn.them.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-SW-Source: 2005-07/txt/msg00125.txt.bz2 Daniel Jacobowitz wrote: > On Mon, Jul 11, 2005 at 05:20:55PM +0100, Jonathan Larmour wrote: > >>The two "global constructors keyed to cyg_scheduler_start" lines are bogus >>frame entries, although those also happened with GDB 6.1. The "corrupt >>stack" whinge is new, and is treated as an error, including terminating >>gdbinit scripts etc. > > > This is already changed in CVS. Okay. I haven't seen that. It still looks like an error to me in frame.c. BTW, my other web searches seem to indicate that a fair few (naive) people are thinking they are having stack corruption because GDB thinks there might be. That's unfortunate. >>I'd be interested if someone could clarify to me what >>the termination conditions for a backtrace actually _are_. i.e. as an OS >>author, how do I initialise a thread context to persuade GDB to stop when >>it reaches the innermost frame. > > In general there's no defined way to do this. If the start routine is > written in assembly, take a look at the example I posted earlier this > year of using dwarf2 unwind information to terminate a backtrace by > marking the return address column as undefined. There's a matching GDB > patch, which was committed to HEAD after 6.3. I've had a search for this and not found anything. I'm probably just not using the right terms. Do you have a pointer, time frame or some search terms I can use to pin this down? Thanks. > For compiler-generated code there's really no useful way to do this. I guess atleast now I know that, which saves me spending more time. Wouldn't it make sense to make such a convention though, such as having a return address of 0? Alternatively, how about adding a new command that allows you to define a set of entry point symbol names? People can then put an appropriate list for themselves or their OS in ~/.gdbinit. Or it can be pre-initialised by the OS support within GDB if there is one. e.g. nm-linux.h. Here's what I'm thinking of: set entry-point-name-list main _start _entry Although handling mangled symbols and multiple languages might be fun. I'm not an expert on such things. Thanks, Jifl -- eCosCentric http://www.eCosCentric.com/ The eCos and RedBoot experts --["No sense being pessimistic, it wouldn't work anyway"]-- Opinions==mine