linux-kernel - Re: [PATCH] fix dubious segment register clear in cpu

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Message-Id: <200608040223.49836.ak@suse.de>
Date:	Fri, 4 Aug 2006 02:23:49 +0200
From:	Andi Kleen <ak@...e.de>
To:	Jeremy Fitzhardinge <jeremy@...p.org>
Cc:	Andrew Morton <akpm@...l.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] fix dubious segment register clear in cpu_init()

On Friday 04 August 2006 01:49, Jeremy Fitzhardinge wrote:
> Fix a very dubious piece of code in
> arch/i386/kernel/cpu/common.c:cpu_init().  This clears out %fs and
> %gs, but clobbers %eax in the process without telling gcc.  It turns
> out that gcc happens to be not using %eax at that point anyway so it
> doesn't matter much, but it looks like a bomb waiting to go off.
> 
> This does end up saving an instruction, because gcc wants %eax==0 for
> the set_debugreg()s below.

Added thanks

-Andi
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