From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:37784) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UfX0f-0006Ca-2b for qemu-devel@nongnu.org; Thu, 23 May 2013 11:00:54 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UfX0c-0007tc-Tu for qemu-devel@nongnu.org; Thu, 23 May 2013 11:00:52 -0400 Received: from mx1.redhat.com ([209.132.183.28]:30729) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UfX0c-0007tS-LG for qemu-devel@nongnu.org; Thu, 23 May 2013 11:00:50 -0400 Message-ID: <519E2F17.1030809@redhat.com> Date: Thu, 23 May 2013 17:00:39 +0200 From: Paolo Bonzini MIME-Version: 1.0 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> In-Reply-To: <20130523145711.GB24256@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit 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: "Michael S. Tsirkin" Cc: aliguori@us.ibm.com, qemu-devel@nongnu.org, David Gibson 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