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Date: Tue, 17 Jun 2008 14:27:46 +0200
From: Aurelien Jarno <aurelien@aurel32.net>
Subject: Re: [Qemu-devel] [PATCH] ppc32 guests: fix computation of XER.{CA,
	OV} in addme, subfme, mullwo
Message-ID: <20080617122746.GA23769@volta.aurel32.net>
References: <200805110204.47184.jseward@acm.org>
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To: Julian Seward <jseward@acm.org>
Cc: qemu-devel@nongnu.org

On Sun, May 11, 2008 at 02:04:47AM +0200, Julian Seward wrote:
> 
> For ppc32 guests, computation of XER.CA and XER.OV in some obscure
> cases is incorrect.  At least, it doesn't produce the same results
> as a real MPC7447, and doesn't appear to be in accordance with the
> instruction set documentation.
> 
> The attached patch fixes it:
> 
> * addme{o}{.}, subfme{o}{.}: compute XER.CA correctly
> 
> * mullwo{.}: sign extend arguments before doing 64-bit
>   multiply, so as to make the XER.OV computation correct

Could you please give us a corner case for at least one of the 
instructions? It would help to clearly understand the problem.

Thanks,
Aurelien

-- 
  .''`.  Aurelien Jarno	            | GPG: 1024D/F1BCDB73
 : :' :  Debian developer           | Electrical Engineer
 `. `'   aurel32@debian.org         | aurelien@aurel32.net
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