Re: [Qemu-devel] [Xen-devel] [PATCH RFC V1 00/11] Xen PCI Passthrough

[Stefano Stabellini]

On Tue, 4 Oct 2011, Avi Kivity wrote:
> On 10/04/2011 05:01 PM, Anthony Liguori wrote:
> >> We also have pci passthrough in qemu-kvm (I think based on the same 
> >> Neocleus
> >> code). Rather than having two pci assignment implementations, I think 
> >> we should
> >> have just one, with the differences (programming the hypervisor) 
> >> abstracted at
> >> that level.
> >
> >
> > I agree in principle but how close is qemu-kvm pci passthrough to a 
> > mergable state?  Would it make sense to merge the Xen code first and 
> > then abstract it?
> 
> Merging either implementation and abstracting it would risk regressions 
> in the other.

Honestly the last time I looked at the kvm passthrough code (admittedly
a while ago), it looked very similar to the xen passthrough code, so I
don't think we would risk much merging either one first and then
abstracting it.


> How about merging both, with the ABIs (command line and qmp) tagged as 
> experimental, and then doing a merge in the same style as 
> i386+x86_64->x86 or the two kvm implementations in qemu?  We can pick 
> one implementation as the merge target and port fixes from the other.

I am OK with this too: it is probably more work but it doesn't risk
loosing any bug fixes.
If you think that kvm passthrough might have several bug fixes that xen
passthrough does not have is probably the right way to go.