From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([208.118.235.92]:36541)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <mst@redhat.com>) id 1UfWws-0002i4-6Z
	for qemu-devel@nongnu.org; Thu, 23 May 2013 10:57:04 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <mst@redhat.com>) id 1UfWwl-0006RK-QR
	for qemu-devel@nongnu.org; Thu, 23 May 2013 10:56:58 -0400
Received: from mx1.redhat.com ([209.132.183.28]:3774)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <mst@redhat.com>) id 1UfWwl-0006RF-Is
	for qemu-devel@nongnu.org; Thu, 23 May 2013 10:56:51 -0400
Date: Thu, 23 May 2013 17:57:11 +0300
From: "Michael S. Tsirkin" <mst@redhat.com>
Message-ID: <20130523145711.GB24256@redhat.com>
References: <1368059472-25071-1-git-send-email-david@gibson.dropbear.id.au>
	<1368059472-25071-6-git-send-email-david@gibson.dropbear.id.au>
	<20130523110407.GB17480@redhat.com> <519E2CE5.2050501@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <519E2CE5.2050501@redhat.com>
Subject: Re: [Qemu-devel] [PATCH 5/8] pci: Replace pci_find_domain() with
 more general pci_root_bus_path()
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: aliguori@us.ibm.com, qemu-devel@nongnu.org, David Gibson <david@gibson.dropbear.id.au>

On Thu, May 23, 2013 at 04:51:17PM +0200, Paolo Bonzini wrote:
> Il 23/05/2013 13:04, Michael S. Tsirkin ha scritto:
> >> > Most current uses of pci_find_domain() are for error or informational
> >> > messages, so the change in identifiers should be harmless.  The exception
> >> > is pci_get_dev_path(), whose results form part of migration streams.  To
> >> > maintain compatibility with old migration streams, the PIIX PCI host is
> >> > altered to always supply "0000" for this path, which matches the old domain
> >> > number (since the code didn't actually support domains other than 0).
> >> > 
> >> > For the pseries (spapr) PCI bridge we use a different platform-unique
> >> > identifier (pseries machines can routinely have dozens of PCI host
> >> > bridges).  Theoretically that breaks migration streams, but given that we
> >> > don't yet have migration support for pseries, it doesn't matter.
> >> > 
> >> > Any other machines that have working migration support including PCI
> >> > devices will need to be updated to maintain migration stream compatibility.
> >> > 
> >> > Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> > AFAIK PC is the only one with working migration, yes, but
> > we have Q35 as well which can be migrated.
> 
> Are we already supporting backwards/forwards migration with Q35?
> 
> Paolo

We released 1.5 with Q35 so we better ...