From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43)
	id 1FMpfO-00042z-Bq
	for qemu-devel@nongnu.org; Fri, 24 Mar 2006 12:01:38 -0500
Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43)
	id 1FMpfI-0003zJ-T5
	for qemu-devel@nongnu.org; Fri, 24 Mar 2006 12:01:36 -0500
Received: from [199.232.76.173] (helo=monty-python.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1FMpfI-0003yr-8u
	for qemu-devel@nongnu.org; Fri, 24 Mar 2006 12:01:32 -0500
Received: from [193.7.176.20] (helo=bender.bawue.de)
	by monty-python.gnu.org with esmtps
	(TLS-1.0:DHE_RSA_3DES_EDE_CBC_SHA:24) (Exim 4.52) id 1FMpg9-0000E0-BB
	for qemu-devel@nongnu.org; Fri, 24 Mar 2006 12:02:25 -0500
Received: from lagash (unknown [194.74.144.146])
	(using TLSv1 with cipher DES-CBC3-SHA (168/168 bits))
	(No client certificate requested)
	by bender.bawue.de (Postfix) with ESMTP id 52DFE44411
	for <qemu-devel@nongnu.org>; Fri, 24 Mar 2006 18:01:29 +0100 (MET)
Received: from ths by lagash with local (Exim 4.60)
	(envelope-from <ths@networkno.de>) id 1FMpfk-0005xf-2b
	for qemu-devel@nongnu.org; Fri, 24 Mar 2006 17:02:00 +0000
Date: Fri, 24 Mar 2006 17:02:00 +0000
Subject: Re: [Qemu-devel] [PATCH] MIPS CP0 not usable in kernel mode?
Message-ID: <20060324170200.GB18630@networkno.de>
References: <4422FB89.6000705@mail.berlios.de>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <4422FB89.6000705@mail.berlios.de>
From: Thiemo Seufer <ths@networkno.de>
Reply-To: qemu-devel@nongnu.org
List-Id: qemu-devel.nongnu.org
List-Unsubscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.gnu.org/pipermail/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: qemu-devel@nongnu.org

On Thu, Mar 23, 2006 at 08:48:25PM +0100, Stefan Weil wrote:
> Hello,
> 
> according to MIPS32 4KE User's Manual, coprocessor CP0 is
> always usable when the processor is running in kernel mode.
> 
> So in kernel mode, exception "CP0 is not usable" should
> not happen.
> 
> I think the boolean expression which checks for the
> exception condition has to be inverted - see my patch
> for translate.c.

This is correct (otherwise it wouldn't be possible to ever enable CP0).
The Linux kernel (plus qemu startup) happens to avoid this particular
case, which might explain it wasn't caught earlier.


Thiemo