From: Jeremy Fitzhardinge <jeremy@goop.org>
Subject: Re: [Xen-devel] Re: [PATCH] xen: remove support for non-PAE 32-bit
Date: Tue, 13 May 2008 14:59:44 +0100
Message-ID: <48299ED0.6020402@goop.org>
References: <48243015.2010801@goop.org> <200805131332.14631.kaiser@informatik.fh-wiesbaden.de> <48298002.5080300@goop.org> <200805131528.09429.kaiser@informatik.fh-wiesbaden.de>
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To: "Robert Kaiser (FH)" <kaiser@informatik.fh-wiesbaden.de>
Cc: xen-devel@lists.xensource.com, Ingo Molnar <mingo@elte.hu>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
List-Id: xen-devel@lists.xenproject.org

Robert Kaiser (FH) wrote:
>> I think there's a bug in qemu's x86 
>> emulation with respect to mis-reporting the eip of an xchg which faults,
>> which may be what you're seeing.
>>     
>
> The eip that was reported was always the same, and there was no xchg 
> instruction at that address. It might have been consistently wrong though 
> (how would I figure this out?).
>   

The symptom I've observed is that qemu reports the first instruction of 
the basic block rather than the exchange itself.  If you "x/10i <fault 
eip>", you should see an xchg before long.

Either way, sounds like a qemu bug which should be reported to them.

    J