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

  • To: Jan Beulich <jbeulich@xxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
  • Date: Thu, 15 Feb 2007 10:33:12 +0000
  • Delivery-date: Thu, 15 Feb 2007 02:32:56 -0800
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: AcdQ7LFF74/AALzfEdu/0gAX8io7RQ==
  • Thread-topic: [Xen-devel] [PATCH] x86 emulation: fix bswap

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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