From mboxrd@z Thu Jan  1 00:00:00 1970
From: Rafal Wojtczuk <rafal@invisiblethingslab.com>
Subject: Re: Bug: Xen panics with #UD in acpi_processor_idle()
Date: Mon, 22 Nov 2010 16:43:35 +0100
Message-ID: <20101122154334.GA11538@email>
References: <20101122130207.GD11110@email>
 <C9103978.AC86%keir@xen.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=iso-8859-2
Return-path: <xen-devel-bounces@lists.xensource.com>
Content-Disposition: inline
In-Reply-To: <C9103978.AC86%keir@xen.org>
List-Unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
List-Post: <mailto:xen-devel@lists.xensource.com>
List-Help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-Subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
Sender: xen-devel-bounces@lists.xensource.com
Errors-To: xen-devel-bounces@lists.xensource.com
To: Keir Fraser <keir@xen.org>
Cc: xen-devel@lists.xensource.com
List-Id: xen-devel@lists.xenproject.org

On Mon, Nov 22, 2010 at 03:15:03PM +0000, Keir Fraser wrote:
> On 22/11/2010 13:02, "Rafal Wojtczuk" <rafal@invisiblethingslab.com> wrote:
> 
> > Hello,
> > 
> > There seems to be an issue with handling of
> > MSR_IA32_MISC_ENABLE_MONITOR_ENABLE bit in MSR_IA32_MISC_ENABLE. The effect
> > is that Xen panics because of #UD after trying to execute "monitor"
> > instruction. Most likely Xen does not bother to set this bit, leaving
> > it to BIOS. If I understand correctly, it is mere reliability issue, not
> > triggerable from any domain.
> 
> The issue appears to be be that we do not check for MWAIT support in CPUID,
> same as native Linux would do (the flag in MISC_ENABLE MSR also affects
> CPUID appropriately). Can you please try the attached patch? If it works I
> will apply it to all our trees.
Yes, with this patch the test machine boots fine.

Regards,
Rafal Wojtczuk