Re: [PATCH 0/7] AlacrityVM guest drivers Reply-To:

["Gregory Haskins" <ghaskins@novell.com>]

>>> On 8/6/2009 at  9:57 AM, in message <4A7AE150.7040009@redhat.com>, Avi Kivity
<avi@redhat.com> wrote: 
> On 08/06/2009 04:45 PM, Gregory Haskins wrote:
>>
>>> (though still rooting for virtio).
>>>      
>>
>> Heh...not to belabor the point to death, but virtio is orthogonal (you keep 
> forgetting that ;).
>>
>> Its really the vbus device-model vs the qemu device-model (and possibly vs the 
> "in-kernel pci emulation" model that I believe Michael is working on).
>>
>> You can run virtio on any of those three.
>>    
> 
> It's not orthogonal.  virtio is one set of ABI+guest drivers+host 
> support to get networking on kvm guests.  AlacrityVM's vbus-based 
> drivers are another set of ABI+guest drivers+host support to get 
> networking on kvm guests.  That makes them competitors (two different 
> ways to do one thing), not orthogonal.

Thats not accurate, though.

The virtio stack is modular.  For instance, with virtio-net, you have

  (guest-side)
|--------------------------
| virtio-net
|--------------------------
| virtio-ring
|--------------------------
| virtio-bus
|--------------------------
| virtio-pci
|--------------------------
                      |
                   (pci)
                      |
|--------------------------
| kvm.ko
|--------------------------
| qemu
|--------------------------
| tun-tap
|--------------------------
| netif
|--------------------------
     (host-side)

We can exchange out the "virtio-pci" module like this:

  (guest-side)
|--------------------------
| virtio-net
|--------------------------
| virtio-ring
|--------------------------
| virtio-bus
|--------------------------
| virtio-vbus
|--------------------------
| vbus-proxy
|--------------------------
| vbus-connector
|--------------------------
                      |
                   (vbus)
                      |
|--------------------------
| kvm.ko
|--------------------------
| vbus-connector
|--------------------------
| vbus
|--------------------------
| virtio-net-tap (vbus model)
|--------------------------
| netif
|--------------------------
     (host-side)


So virtio-net runs unmodified.  What is "competing" here is "virtio-pci" vs "virtio-vbus".  Also, venet vs virtio-net are technically competing.  But to say "virtio vs vbus" is inaccurate, IMO.

HTH
-Greg