From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([208.118.235.92]:37086)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <mst@redhat.com>) id 1SUZMn-0004oo-4O
	for qemu-devel@nongnu.org; Wed, 16 May 2012 04:13:58 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <mst@redhat.com>) id 1SUZMl-00085b-7F
	for qemu-devel@nongnu.org; Wed, 16 May 2012 04:13:52 -0400
Received: from mx1.redhat.com ([209.132.183.28]:38158)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <mst@redhat.com>) id 1SUZMk-00085S-Vv
	for qemu-devel@nongnu.org; Wed, 16 May 2012 04:13:51 -0400
Date: Wed, 16 May 2012 11:13:42 +0300
From: "Michael S. Tsirkin" <mst@redhat.com>
Message-ID: <20120516081341.GB3183@redhat.com>
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> <4FB36001.9030008@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <4FB36001.9030008@redhat.com>
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: Paolo Bonzini <pbonzini@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>

On Wed, May 16, 2012 at 10:06:25AM +0200, Paolo Bonzini wrote:
> 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.

So driver tells firmware (meaning acpi? how?) that it's ok
to do surprize removal?

> Of course it has to do it early enough so that the guest
> doesn't crash.
> 
> Paolo

What does early enough mean and how do we ensure that?

-- 
MST