Re: [Qemu-devel] [PATCH 5/8] pci: Replace pci_find_domain() with more general pci_root_bus_path()

[Michael S. Tsirkin]

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 <address@hidden>
> > 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 ...