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Re: [Xen-devel] [PATCH] x86 emulation: fix bswap

To: Jan Beulich <jbeulich@xxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] x86 emulation: fix bswap
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Thu, 15 Feb 2007 10:33:12 +0000
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On 15/2/07 10:22, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote:

> REX.R needs to be decoded and since bswap on a 16-bit operand is undefined,
> it is best to have hardware execute this so the emulation result matches
> hardware behavior. Since it is simple to do, faster, and smaller, also let
> hardware do 32- and 64-bit ones.

Can 'undefined' behaviour include e.g. #UD?

 -- Keir



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