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Date: Thu, 03 Oct 2002 12:03:27 +0200
To: Keith Owens <kaos@sgi.com>, linux-kernel@vger.kernel.org
From: Mike Galbraith <efault@gmx.de>
Subject: Re: [OT] backtrace 
In-Reply-To: <7453.1033637889@ocs3.intra.ocs.com.au>
References: <Your message of "Thu, 03 Oct 2002 09:31:06 +0100." <3D9C004A.3080006@corvil.com>
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At 07:38 PM 10/3/2002 +1000, Keith Owens wrote:
>On Thu, 03 Oct 2002 09:31:06 +0100,
>Padraig Brady <padraig.brady@corvil.com> wrote:
> >Sorry to go off topic but this tip is just too useful IMHO.
> >You can do the same in userspace with glibc. Details here:
> >http://www.iol.ie/~padraiga/backtrace.c
>
>info libc, /backtrace.
>
>      Note that certain compiler optimisations may interfere with
>      obtaining a valid backtrace.  Function inlining causes the inlined
>      function to not have a stack frame; tail call optimisation
>      replaces one stack frame with another; frame pointer elimination
>      will stop `backtrace' from interpreting the stack contents
>      correctly.
>
>Most architectures compile with -fomit-frame-pointer (except for ARM
>where RMK does it differently).  Neither gdb not glibc can cope with
>kernel code built with -fomit-frame-pointer.  See the horrible
>heuristics kdb has to apply to get any sort of backtrace on i386.

IIRC, r~ once mentioned that it was going to get worse. He also mentioned 
dwarf2 (sp) as a possible solution.  Did you ever look into that?

         -Mike

(I didn't.  Elf->Dwarf transmogrification of kernel is way out of my league)

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