From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([208.118.235.92]:56147)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <paolo.bonzini@gmail.com>) id 1SUZFw-00032m-2r
	for qemu-devel@nongnu.org; Wed, 16 May 2012 04:06:53 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <paolo.bonzini@gmail.com>) id 1SUZFp-0006bM-7K
	for qemu-devel@nongnu.org; Wed, 16 May 2012 04:06:47 -0400
Received: from mail-pb0-f45.google.com ([209.85.160.45]:42287)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <paolo.bonzini@gmail.com>) id 1SUZFo-0006ab-Tp
	for qemu-devel@nongnu.org; Wed, 16 May 2012 04:06:41 -0400
Received: by pbbro12 with SMTP id ro12so991916pbb.4
	for <qemu-devel@nongnu.org>; Wed, 16 May 2012 01:06:38 -0700 (PDT)
Sender: Paolo Bonzini <paolo.bonzini@gmail.com>
Message-ID: <4FB36001.9030008@redhat.com>
Date: Wed, 16 May 2012 10:06:25 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
MIME-Version: 1.0
References: <1337095599-28836-1-git-send-email-anthony.perard@citrix.com>
	<1337095599-28836-5-git-send-email-anthony.perard@citrix.com>
	<20120515210053.GB12039@redhat.com>
In-Reply-To: <20120515210053.GB12039@redhat.com>
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] [PATCH 4/4] xen: Fix PV-on-HVM
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: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Anthony PERARD <anthony.perard@citrix.com>, Xen Devel <xen-devel@lists.xen.org>, QEMU-devel <qemu-devel@nongnu.org>, Anthony Liguori <anthony@codemonkey.ws>, Stefano Stabellini <stefano.stabellini@eu.citrix.com>

Il 15/05/2012 23:00, Michael S. Tsirkin ha scritto:
> On Tue, May 15, 2012 at 04:26:39PM +0100, Anthony PERARD wrote:
>> In the context of PV-on-HVM under Xen, the emulated nics are supposed to be
>> unplug before the guest drivers are initialized. This mean that there must be
>> unplug without the consent of the guest.
>>
>> Without this patch, the guest end up with two nics with the same MAC, the
>> emulated nic and the PV nic.
>>
>> Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
> 
> OK, so on Xen there are special devices that can be safely removed
> without telling the guest?  Does there need to be regular hotplug for
> these devices too? Or can it be always surprise removal?

On Xen the PV drivers can ask the firmware to surprise-remove the
emulated NICs.  Of course it has to do it early enough so that the guest
doesn't crash.

Paolo