Re: Merging kvm-apic into qemu-kvm

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2012-01-26 16:15, Avi Kivity wrote:
> The changes to kvm-apic are so drastic, that merging them into qemu-kvm
> in the normal way won't work.  I can consider just dropping the existing
> implementation and switching to the new one, but the comment at the end
> 
>     Make the basic in-kernel irqchip support selectable via
>     -machine ...,kernel_irqchip=on. Leave it off by default until it can
>     fully replace user space models.
> 
> suggests that things are still missing.
> 
> Jan, what's still missing?

- in-kernel PIT (patches done, waiting for some upstream bits to be
  merged first)
- TPR acceleration via VAPIC (WIP)
- MSI support

The latter is the big chunk. It requires quite some
refactoring/enhancement of the MSI layer. I posted the first version
last year. We need to agree on the design, then probably switch qemu-kvm
over while pushing generic bits upstream. And then we can extend the
upstream in-kernel *PIC using that new interfaces. Once upstream works
with MSI, we can switch qemu-kvm over, leaving basically only
device-assignment as the last missing bit.

>  Any idea on how to proceed?

I had a qemu-kvm branch here that disables the upstream in-kernel *PIC
in favor of its current version. I still need to refresh that work (was
based on an earlier revision), but it was not that horrible. Let me check...

Jan

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