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 <da...@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? > > > > 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
