Re: [Qemu-devel] Re: [PATCH 2/3] qemu: make cirrus init value pci spec compliant

[Jamie Lokier]

Avi Kivity wrote:
> On 10/08/2009 06:06 PM, Michael S. Tsirkin wrote:
> >On Thu, Oct 08, 2009 at 05:29:29PM +0200, Avi Kivity wrote:
> >   
> >>On 10/08/2009 04:52 PM, Michael S. Tsirkin wrote:
> >>     
> >>>PCI memory should be disabled at reset, otherwise
> >>>we might claim transactions at address 0.
> >>>I/O should also be disabled, although for cirrus
> >>>it is harmless to enable it as we do not
> >>>have I/O bar.
> >>>
> >>>Note: need bios fix for this patch to work:
> >>>currently pc-bios incorrently assumes that it does not
> >>>need to enable i/o unless device has i/o bar.
> >>>
> >>>Signed-off-by: Michael S. Tsirkin<address@hidden>
> >>
> >>This needs to be conditional on the machine type.  Old machines must
> >>retain this code for live migration to work (we need to live migrate the
> >>bios, so we can't assume the bios fix is in during live migration from
> >>older qemus).
> >>     
> >No, if you migrate from older qemu you will be fine as command
> >is enabled there on init.
> >   
> 
> Right.

No, I think Avi was right the first time.

Migrating from an older qemu will be fine at first, but at the next
reset _following_ migration, it'll be running the old BIOS on a new
qemu and fail.

-- Jamie