From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:39696) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UfX5u-0002Ti-Mf for qemu-devel@nongnu.org; Thu, 23 May 2013 11:06:26 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UfX5n-0001DT-2Q for qemu-devel@nongnu.org; Thu, 23 May 2013 11:06:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48389) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UfX5m-0001D7-OG for qemu-devel@nongnu.org; Thu, 23 May 2013 11:06:10 -0400 Date: Thu, 23 May 2013 18:06:29 +0300 From: "Michael S. Tsirkin" Message-ID: <20130523150629.GA24405@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> <20130523145711.GB24256@redhat.com> <519E2F17.1030809@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <519E2F17.1030809@redhat.com> Subject: Re: [Qemu-devel] [PATCH 5/8] pci: Replace pci_find_domain() with more general pci_root_bus_path() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: kwolf@redhat.com, agraf@suse.de, aliguori@us.ibm.com, qemu-devel@nongnu.org, David Gibson On Thu, May 23, 2013 at 05:00:39PM +0200, Paolo Bonzini wrote: > Il 23/05/2013 16:57, Michael S. Tsirkin ha scritto: > > 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 > >>> 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? > > > > We released 1.5 with Q35 so we better ... > > We released 1.5 with Q35 migration disabled by default, IIRC to enable > it you need to remove the AHCI controller with -nodefaults. I think > bending the rules is still reasonable. > > Paolo Which reminds me, does someone plan to look into fixing migration for AHCI? -- MST