[Spice-devel] [Qemu-devel] seamless migration with spice

[Yonit Halperin]

On 03/13/2012 09:40 AM, Gerd Hoffmann wrote:
>    Hi,
>
>> It is not easy when you have 2 components, and it is much less easy when
>> you have 3 or 4 components. So why make it more complicated if you can
>> avoid it. Especially since there is no functional reason for making the
>> qemu/client capabilities/versions dependent on the server internal data.
>
> qemu has ways to handle compatibility in the vmstate format.  We can use
> those capabilities.  That of course requires exposing the structs to be
> saved to qemu and adds some complexity to the qemu<->  spice interface.
>
> What session state is needed by the target?
> What of this can be negotiated between client and target host without
> bothering the source?
> What needs be transfered from source to target, either directly or via
> client?
>
>>> If this is a hard requirement then using the vmstate channel isn't going
>>> to work.  The vmstate is a one-way channel, no way to negotiate anything
>>> between source and target.
>>>
>> We can do this via the client.
>
> Then you can send the actual state via client too.
> Out-of-band negotiation for the blob send via vmstate scares me.
>
> Can we please start with a look at which state we actually have to send
> over?
Ok, I can take the display and sound channels.
Alon, can you take the smartcard?
Hans, spicevmc?
Arnon, the main channel, mainly the agent stuff?

Thanks,
Yonit.

>
> cheers,
>    Gerd