Re: [Qemu-devel] [PATCH] Migration compatibility for serial

[Michael S. Tsirkin]

On Wed, Jun 17, 2015 at 06:16:19PM +0200, Paolo Bonzini wrote:
> 
> 
> On 17/06/2015 16:50, Michael S. Tsirkin wrote:
> > > > I just tried, set prog_if to different values, sure it failed.
> > > 
> > > How so?  It's just a byte in config space.

Why does it fail? Because pci core migrates it and validates it
on both sides.

> > > But even then, fixing
> > > migration is just a side effect of keeping config space consistent for a
> > > given machine type (i.e. not changing hardware type under the guest's 
> > > feet).
> > 
> > David's patches are also guest visible, are they not?
> > We are losing state guest can indirectly observe, right?
> 
> One case only happens during migration, the other does not.
> 
> Paolo

True - apparently the bug was only in the migration stream,
not the functionality?

-- 
MST