On Tue, Dec 14, 2010 at 11:34:53AM -0700, Alex Williamson wrote: > On Tue, 2010-12-14 at 14:26 +0200, Michael S. Tsirkin wrote: > > On Mon, Dec 13, 2010 at 10:04:24PM -0700, Alex Williamson wrote: > > > > > > I've only ever seen config[PCI_SECONDARY_BUS] be non-zero for an > > > assigned device, so I'm pretty sure we're not going to hurt migration, > > > but the code is clearly wrong and I'd like to make sure we don't trip on > > > a migration failure for a minor device config space change. > > > > Which reminds me: maybe just mark nested bridges as non-migrateable > > for now? Care writing such a patch? > > Hmm, this is trickier than it sounds.
Hmm, since 0 is put in the path instead of the bridge number, will the correct bridge be restored? > We're really only broken wrt > migration if a device under a bridge calls qemu_ram_alloc. I guess there's more broken-ness. What exactly breaks qemu_ram_alloc? > Any device > is free to do this, but typically it only happens via > pci_add_option_rom() (not counting vga as typical). So maybe the better > approach for now is to prevent the problem by disallowing option ROMs > for devices below a bridge. We obviously risk devices coming along that > allocate RAM on their own, but we could still allow the most common > issue with almost no lost functionality (assuming no one wants to boot > off that nested device). Thoughts? Thanks, > > Alex
