From: "Amit S. Kale" <amitkale@emsyssoft.com>
Organization: EmSysSoft
To: Andi Kleen <ak@muc.de>, Tom Rini <trini@kernel.crashing.org>
Subject: Re: kgdb for mainline kernel: core-lite [patch 1/3]
Date: Tue, 9 Mar 2004 10:06:00 +0530
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Cc: Andrew Morton <akpm@osdl.org>, linux-kernel@vger.kernel.org,
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On Monday 08 Mar 2004 10:27 pm, Andi Kleen wrote:
> Tom Rini <trini@kernel.crashing.org> writes:
> > Here's where what Andi said about being able to get the pt_regs stuff
> > off the stack (I think that's what he said at least) started to confuse
> > me slightly.  But if I understand it right (and I never got around to
> > testing this) we can replace the do_schedule() stuffs at least with
> > something like kgdb_get_pt_regs(), since (and I lost my notes on this,
> > so it's probably not quite right) (thread_info->esp0)-1
>
> No, that's the user space registers.
>
> You don't need these registers really as long as you have the
> correct dwarf2 CFI description of all the code involved. gdb
> is then able to reconstruct them using the C stack by itself.
>
> All it needs for that is esp and eip.

Yes. But as things stand, gdb 6.0 doesn't show stack traces correctly with esp 
and eip got from switch_to and gas 2.14 can't handle i386 dwarf2 CFI. Do we 
want to enforce getting a CVS version of gdb _and_ gas to build kgdb? 
Certainly not.

Current kgdb has a dependency on gdb 6.0. My RH9 gdb (5.3.x) can't talk with 
kgdb and complains about too long [sf]ThreadInfo packets. I don't like that 
either, but gdb 6.x should be standard on all distributions based on 2.6 
kernels, so that's acceptable.

-Amit

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