[Spice-devel] [PATCH] server: add async io support

[Gerd Hoffmann]

   Hi,

>> While we are busy updating the interface: can we please also add a
>> callback which is called by spice server each time it updates a
>> surface in qxl device memory?
> you mean whenever we render something? I guess I'll allow it to be
> NULL at first cause I don't want to bother implementing it on the other
> side atm.

Sure.  Also needs a minor version check to figure whenever the callback 
field is valid (pretty much like the channel_event callback is handled, 
see recent discussion @ spice-devel).

> Let's settle on the signature since I'm not even sure where
> you'd want to call it - for every render operation I presume, but sounds like
> a bit too much (but again, I'm not sure why you want that anyway).

Not for every single op.  Having a single callback at the end of a batch 
of operations is fine.  I want it for better dirty tracking, i.e. inform 
kvm that those pages have been touched by the spice renderer and need to 
be transfered in case live migration is running.  That way the device 
memory can be streamed over during the live stage. Today this is done in 
the final stage, after the guest has been stopped.

> void (*surface_updated)(QXLInstance *qxl, uint32_t surface_id, struct QXLRect *rect)

Looks good.

cheers,
   Gerd