linux-kernel - Re: [patch] i386: fix one case of stuck dwarf2 unwinder II

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Message-ID: <200608060314_MC3-1-C73C-AEAE@compuserve.com>
Date:	Sun, 6 Aug 2006 03:11:56 -0400
From:	Chuck Ebbert <76306.1226@...puserve.com>
To:	Andi Kleen <ak@...e.de>
Cc:	linux-kernel <linux-kernel@...r.kernel.org>,
	Jan Beulich <jbeulich@...ell.com>,
	Dave Jones <davej@...hat.com>,
	Jesper Juhl <jesper.juhl@...il.com>,
	Andrew Morton <akpm@...l.org>
Subject: Re: [patch] i386: fix one case of stuck dwarf2 unwinder II

In-Reply-To: <200608060805.06821.ak@...e.de>

On Sun, 6 Aug 2006 08:05:06 +0200, Andi Kleen wrote:

> Hmm, actually I applied it but then I had doubts it actually 
> works -- I think you don't need _stext but the code before
> the first call in head. Since head.S doesn't do a call
> that's probably start_kernel

But head.S does do a call (on i386 but not x86_64 AFAICT):

| #ifdef CONFIG_SMP
|        movb ready, %cl
|        movb $1, ready
|        cmpb $0,%cl
|        je 1f                   # the first CPU calls start_kernel
|                                # all other CPUs call initialize_secondary
|        call initialize_secondary
|        jmp L6
| 1:
| #endif /* CONFIG_SMP */
|        call start_kernel
| L6:
|        jmp L6                  # main should never return here, but
|                                # just in case, we know what happens.

And the backtraces I saw ended up at L6:

| DWARF2 unwinder stuck at 0xc0100210

System.map on i386 SMP says:

| c0100210 t L6

-- 
Chuck

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