From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([140.186.70.92]:59505)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <andi@firstfloor.org>) id 1R8PIi-0005nN-QS
	for qemu-devel@nongnu.org; Tue, 27 Sep 2011 00:29:53 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <andi@firstfloor.org>) id 1R8PId-0005f7-Tg
	for qemu-devel@nongnu.org; Tue, 27 Sep 2011 00:29:48 -0400
Received: from mga03.intel.com ([143.182.124.21]:61353)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <andi@firstfloor.org>) id 1R8PId-0005ew-Lf
	for qemu-devel@nongnu.org; Tue, 27 Sep 2011 00:29:43 -0400
From: Andi Kleen <andi@firstfloor.org>
References: <4E802DDD.8090100@siemens.com>
	<CAGdaadZ=w-J=krctPHWO2MD4_h2ByPkW9GzERCWLNN3YBZ-RGA@mail.gmail.com>
	<CABoDooMzOLFAapuXYFRVeK6ohO9apkZwFqdXCh6FnxNeDj=A3A@mail.gmail.com>
	<4E80B944.4040209@redhat.com> <4E80D5EF.4090705@twiddle.net>
	<4E80D7E9.4050203@redhat.com>
	<CAFEAcA-kkobH763sPVs3zbgh6J9LTsJjo5XkEqHC5g3TDwaMMg@mail.gmail.com>
Date: Mon, 26 Sep 2011 21:29:37 -0700
In-Reply-To: <CAFEAcA-kkobH763sPVs3zbgh6J9LTsJjo5XkEqHC5g3TDwaMMg@mail.gmail.com>
	(Peter Maydell's message of "Mon, 26 Sep 2011 21:19:15 +0100")
Message-ID: <m2sjniip5a.fsf@firstfloor.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Subject: Re: [Qemu-devel] [PATCH] tcg: Remove stack protection from helper
	functions
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: Jan Kiszka <jan.kiszka@siemens.com>, qemu-devel <qemu-devel@nongnu.org>, Avi Kivity <avi@redhat.com>, Laurent Desnogues <laurent.desnogues@gmail.com>, Mulyadi Santosa <mulyadi.santosa@gmail.com>, Richard Henderson <rth@twiddle.net>

Peter Maydell <peter.maydell@linaro.org> writes:
>
> The answer is that the edge cases basically never match. No CPU
> architecture does handling of NaNs and input denormals and output
> denormals and underflow checks and all the rest of it in exactly
> the same way as anybody else. (In particular x86 is pretty crazy,

Can you clarify this? 

IEEE754 is pretty strict on how all these things are handled
and to my knowledge all serious x86 are fully IEEE compliant.
Or are you refering to the x87 80bits expansion? While useful
that's not used anymore with SSE.

On the other hand qemu is not very good at it, e.g. with x87
it doesn't even pass paranoia.

-Andi