Re: Balloon driver?

Carsten Otte
2007-06-06T16:04:35Z

Dor Laor wrote:
> I agree that pci interface isn't ideal, the advantage is that platforms
> that do support pci don't have to implement a virtualized bus, and pci
> is PnP device. This was the motivation behind using it, especially for
> Windows.
In understand that requirement, and I think being able to surface
paravirtual functions/devices to the guest as PCI device needs to be a
key feature. For windows guests.

> Now that more platforms are joining the KVM wagon, we should define a
> common bus. PCI was a overkill anyway - its irq are shared and we don't
> have to use its io/mmio areas.
> Do you guys have something to start with?
We do have something basic, our vdev bus. The bad thing is, it is
platform specific. I really prefer to aim for an idea that Arnd came
up with when discussing this issue:
We could define a virtual device bus. We would have platform specific
bus implementations which rely on hypercalls, interrupts, and shared
memory in the pure paravirtual case. And we need a second bus driver,
which is based on a pci device. Just similar to the situation where a
PCI device is a USB host adapter.
Now functionality like device drivers can sit on top of the
abstraction layer. We need to invent a similar abstraction on the
hypervisor side, which is a tricky task indeed.
The best approach into this direction I have seen so far is not our
own vdev thing but Rusty's virtio infrastructure. That's what I think
I would start with.

so long,
Carsten