From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from [140.186.70.92] (port=48914 helo=eggs.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1P3wYF-0002h5-4w
	for qemu-devel@nongnu.org; Thu, 07 Oct 2010 15:54:52 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <anthony@codemonkey.ws>) id 1P3wYD-00006D-UG
	for qemu-devel@nongnu.org; Thu, 07 Oct 2010 15:54:50 -0400
Received: from mail-yx0-f173.google.com ([209.85.213.173]:64266)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <anthony@codemonkey.ws>) id 1P3wYD-000063-Rk
	for qemu-devel@nongnu.org; Thu, 07 Oct 2010 15:54:49 -0400
Received: by yxf34 with SMTP id 34so128554yxf.4
	for <qemu-devel@nongnu.org>; Thu, 07 Oct 2010 12:54:49 -0700 (PDT)
Message-ID: <4CAE2586.1080003@codemonkey.ws>
Date: Thu, 07 Oct 2010 14:54:46 -0500
From: Anthony Liguori <anthony@codemonkey.ws>
MIME-Version: 1.0
Subject: Re: [Qemu-devel] [PATCH 0/2] USB CCID device
References: <2052681331.708791286437179606.JavaMail.root@zmail06.collab.prod.int.phx2.redhat.com>
In-Reply-To: <2052681331.708791286437179606.JavaMail.root@zmail06.collab.prod.int.phx2.redhat.com>
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.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: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Alon Levy <alevy@redhat.com>
Cc: qemu-devel@nongnu.org, Gerd Hoffmann <kraxel@redhat.com>

On 10/07/2010 02:39 AM, Alon Levy wrote:
> ----- "Anthony Liguori"<anthony@codemonkey.ws>  wrote:
>
>    
>> On 10/06/2010 03:55 AM, Gerd Hoffmann wrote:
>>      
>>> On 10/06/10 02:28, Alon Levy wrote:
>>>        
>>>>          
>>>>> Does this work with live migration?  I can't see how it would.
>>>>>
>>>>>            
>>>> No, it doesn't right now. It would require cooperation with the
>>>>          
>> client,
>>      
>>>> to tell it to reconnect to the target qemu (kind of like spice).
>>>>          
>>> I think until we have this migration should have pretty much the
>>>        
>> same
>>      
>>> effect as a chardev disconnect, i.e. detach the usb device (which
>>>        
>> the
>>      
>>> guest will see as unplug).
>>>        
>> Better yet, mark the guest as unmigrateable and let the management
>> tool
>> unplug the usb device before migration and replug it after migration.
>>
>> It's the same principle behind device assignment.
>>
>>      
> Is there any way to also get a pre_migrate callback with register_device_unmigratable?
> I'd like to send a VSC_Reconnect message, then the guest sees an unplug, then migration,
>    

No.  The disconnect needs to happen in the management tooling layer.   
Same is true for any device doing hardware passthrough.

Automagic unplugging/plugging during migration is not a good idea 
universally so it's something that needs to happen as a policy at the 
management level.

Regards,

Anthony Liguori

> then (no plug yet since the device is marked as auto_attach=0) client reconnects
> (actually this happens before but to a paused machine waiting for migration), and then
> causes attachement, same as a new machine.
>
>    
>> Regards,
>>
>> Anthony Liguori
>>
>>      
>>> Needs some code though, at minimum you'll have to xfer the connected
>>>        
>>      
>>> state from the migration source and have some bits in post_load()
>>> which do attach/detach if needed.
>>>
>>> cheers,
>>>    Gerd
>>>
>>>