Re: [Qemu-devel] [PATCH v2 3/8] fdc: Introduce fdctrl->phase

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Peter Maydell (peter.maydell@linaro.org) wrote:
> On 29 May 2015 at 11:34, Dr. David Alan Gilbert <dgilbert@redhat.com> wrote:
> > It's the destination I'm worried about here, not the source; lets say
> > you have two devices, a & b.  'a' gets serialised, but then 'b' finds
> > it has to wait, so we return to running the source and sending pages
> > across.   However the destination has already loaded the 'a' device state;
> > so that when we serialise again we send a new 'a' device state'; I'm
> > worrying here that the destination 'a' state loader would get upset
> > trying to load the same state twice without somehow resetting it.
> 
> You would need to reset the system before resending device state,
> I think. Device implementations rely on knowing that migration happens
> into a freshly reset device, and we don't have any way of resetting
> a single device, only the whole system at once.

I don't think you can do a device (or certainly not a system) reset
without resending the contents of RAM which was the whole point of
not restarting the migration from the beginning.

Dave

> 
> -- PMM
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK