linux-kernel - Re: Andi, you broke my laptop :-)

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Message-ID: <20070510141942.GM14898@one.firstfloor.org>
Date:	Thu, 10 May 2007 16:19:42 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Joerg Roedel <joerg.roedel@....com>
Cc:	Andi Kleen <andi@...stfloor.org>,
	Pete Zaitcev <zaitcev@...hat.com>, ak@...e.de,
	linux-kernel@...r.kernel.org, Benny Halevy <bhalevy@...asas.com>,
	akpm@...ux-foundation.org
Subject: Re: Andi, you broke my laptop :-)

On Thu, May 10, 2007 at 03:35:56PM +0200, Joerg Roedel wrote:
> On Thu, May 10, 2007 at 03:01:44PM +0200, Andi Kleen wrote:
> > On Wed, May 09, 2007 at 12:56:16PM -0700, Pete Zaitcev wrote:
> > > Hi, Andi:
> > > 
> > > The attached patch (actually, git show output) makes my Dell 1501 to hang
> > > on boot. Sorry, I have no clue why... The culprit is found with git bisect.
> > > But yes, it's an AMD MK-36. I use an x86_64 kernel. It is 100% reproducible.
> > 
> > MK-36? Does it have SVM? 
> > 
> > Anyways we previously had issues with this being miscompiled, but 
> > I thought the latest patch should have been ok. What compiler do you use?
> > 
> > Can you send me a disassembly listing of arch/x86_64/kernel/time.o?
> 
> I debugged this problem a bit and my compiler[1]interprets the =A
> constraint as %rax instead of %edx:%eax on x86_64 which causes the
> problem. The appended patch provides a workaround for this and fixed the
> hang on my machine.

Hmm yes now I can reproduce it too. I didn't see any hangs so i suppose 
my (and that of most -mm tester's) compiled binary always happened to have a 
suitable value in edx

Thanks for the patch.

-Andi
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