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
