Re: [Qemu-devel] live migration vs device assignment (motivation)

[Pavel Fedin]

 Hello!

> A dedicated IRQ per device for something that is a system wide event
> sounds like a waste.  I don't understand why a spec change is strictly
> required, we only need to support this with the specific virtual bridge
> used by QEMU, so I think that a vendor specific capability will do.
> Once this works well in the field, a PCI spec ECN might make sense
> to standardise the capability.

 Keeping track of your discussion for some time, decided to jump in...
 So far, we want to have some kind of mailbox to notify the quest about 
migration. So what about some dedicated "pci device" for
this purpose? Some kind of "migration controller". This is:
a) perhaps easier to implement than capability, we don't need to push anything 
to PCI spec.
b) could easily make friendship with Windows, because this means that no bus 
code has to be touched at all. It would rely only on
drivers' ability to communicate with each other (i guess it should be possible 
in Windows, isn't it?)
c) does not need to steal resources (BARs, IRQs, etc) from the actual devices.

Kind regards,
Pavel Fedin
Expert Engineer
Samsung Electronics Research center Russia