From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43)
	id 1MGop9-0000D5-DN
	for qemu-devel@nongnu.org; Wed, 17 Jun 2009 02:40:43 -0400
Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43)
	id 1MGop4-0008Oc-IP
	for qemu-devel@nongnu.org; Wed, 17 Jun 2009 02:40:42 -0400
Received: from [199.232.76.173] (port=59942 helo=monty-python.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1MGop4-0008OJ-EK
	for qemu-devel@nongnu.org; Wed, 17 Jun 2009 02:40:38 -0400
Received: from mx2.redhat.com ([66.187.237.31]:56080)
	by monty-python.gnu.org with esmtp (Exim 4.60)
	(envelope-from <avi@redhat.com>) id 1MGop3-0003Pp-RI
	for qemu-devel@nongnu.org; Wed, 17 Jun 2009 02:40:38 -0400
Message-ID: <4A388F4F.8000900@redhat.com>
Date: Wed, 17 Jun 2009 09:38:07 +0300
From: Avi Kivity <avi@redhat.com>
MIME-Version: 1.0
Subject: Re: Configuration vs. compat hints [was Re: [Qemu-devel] [PATCHv3
	03/13] qemu: add routines to manage PCI capabilities]
References: <4A364B53.9080007@codemonkey.ws> <4A364FE0.40204@redhat.com>
	<4A3651EB.3070204@codemonkey.ws> <4A36555A.4090303@redhat.com>
	<4A3659A0.3050108@codemonkey.ws>
	<20090615143737.GB14405@redhat.com>
	<4A3662BA.6030304@codemonkey.ws>
	<20090615150804.GH7233@redhat.com> <4A3664EE.30207@redhat.com>
	<4A3665A0.7000702@redhat.com>
	<20090616183222.GH11893@shareable.org>
In-Reply-To: <20090616183222.GH11893@shareable.org>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
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: Jamie Lokier <jamie@shareable.org>
Cc: Carsten Otte <cotte@de.ibm.com>, Rusty Russell <rusty@rustcorp.com.au>, kvm@vger.kernel.org, "Michael S. Tsirkin" <mst@redhat.com>, Glauber Costa <glommer@redhat.com>, dlaor@redhat.com, qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org, Blue Swirl <blauwirbel@gmail.com>, Christian Borntraeger <borntraeger@de.ibm.com>, Paul Brook <paul@codesourcery.com>, Mark McLoughlin <markmc@redhat.com>

On 06/16/2009 09:32 PM, Jamie Lokier wrote:
> Avi Kivity wrote:
>    
>> Another issue is enumeration.  Guests will present their devices in the
>> order they find them on the pci bus (of course enumeration is guest
>> specific).  So if I have 2 virtio controllers the only way I can
>> distinguish between them is using their pci slots.
>>      
>
> virtio controllers really should have a user-suppliable string or UUID
> to identify them to the guest.  Don't they?
>    

virtio controllers don't exist.  When they do, they may have a UUID or 
not, but in either case guest infrastructure is in place for reporting 
the PCI slot, not the UUID.

virtio disks do have a UUID.  I don't think older versions of Windows 
will use it though, so if you reorder your slots you'll see your drive 
letters change.  Same with Linux if you don't use udev by-uuid rules.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.