Re: [Qemu-devel] [PATCH 0/4] pc: inform SeaBIOS where 64-bit PCI hole start and PCI mappings cleanup

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Oct 29, 2013 at 11:08:56AM +0100, Igor Mammedov wrote:
> On Wed, 16 Oct 2013 12:20:45 +0300
> "Michael S. Tsirkin" <mst@redhat.com> wrote:
> 
> > On Wed, Oct 16, 2013 at 10:49:10AM +0200, Igor Mammedov wrote:
> > > * simplify PCI address space mapping into system address space,
> > >   replacing code duplication in piix/q53 PCs with helper function
> > 
> > I think this does not go far enough.
> > 
> > I was always wondering about PCI hole in QEMU.
> > Some real PCs have a "PCI hole" where PCI
> > masks real memory, but PIIX does not do this,
> > instead PCI is whenever RAM does not mask it.
> > 
> > So it looks like the hole concept is a left-over
> > from when we didn't have priorities in the memory API.
> > How about we remove them?
> > See patch below.
> > I did a quick boot test and it seems to work, of course
> > it needs much more testing.
> > It's on top of Marcel's series adding negative priorities,
> > so works on top of the acpi branch or the pci branch.
> I have done quite thorough testing and it works well except of
> one caveat, it breaks migration due to different memory regions
> layout.
> 
> So we'll have to keep an old aliasing scheme at least for old
> machine types. Having that in mind do we still want to add
> an extra implementation as you suggested?

Sorry I didn't answer this question.
I think it's a bug - PCI hole should not affect migration.