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Date: Fri, 24 May 2013 23:44:21 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] FPU x86 instructions error
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To: Clemens Kolbitsch <kolbitsch@lastline.com>
Cc: "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>

Il 24/05/2013 23:39, Clemens Kolbitsch ha scritto:
> Hi guys,
> 
> we recently had an issue with running a program using FPU instructions
> to obtain the current EIP (basically a weird way of "call 0; pop eax")
> that was not working on QEMU (with TCG).
> 
> Looking at the problem, we found this patch to be useful/fixing the issue:
> 
> https://launchpadlibrarian.net/140457932/patch-qemu-1.5.0-fpip.diff
> 
> Looking through the DEVEL archives, I found this patch
> 
> http://lists.nongnu.org/archive/html/qemu-devel/2011-06/msg01206.html
> 
> that adds the FPU flags to the environment, but is only using them for KVM.
> 
> I was wondering - since the above patch is rather old, you have
> probably come across it before - if there was a reason for not
> including it in QEMU (I checked in git:master and it's not applied).
> If there isn't, maybe it'd be worth re-considering :)

For the TCG patch, there is no Signed-off-by and using a helper is not
necessary.

For the KVM patch, it simply fell through the cracks, I believe.

Paolo