Re: [Qemu-devel] [PATCH 7/7 v5] VMXNET3 paravirtualized device implementation Interface type "vmxnet3" added.

[Daniel P. Berrange]

On Tue, Apr 10, 2012 at 04:47:19PM +0100, Stefan Hajnoczi wrote:
> On Wed, Apr 4, 2012 at 12:44 PM, Izik Eidus
> <address@hidden> wrote:
> > What about this patch?, everything that was asked from Dmitry was
> > accomplished...
> > What prevent us from progressing with merging this patch?
> 
> Hang on, I asked what the point of the VMware paravirt device models
> is.  I don't think that was ever answered fully.
> 
> I know it makes migration of existing VMware guests easy, but now we
> have the burden of maintaining these device models, whose feature set
> and performance will never be equivalent to virtio.  The reason is
> because we cannot extend the device spec without breaking guests (we
> don't control the device specification and therefore cannot add new
> features) and we now have twice as much performance optimization work
> if we want the same level of performance as virtio devices.
> 
> For these reasons, I think that VMware device models can only ever be
> 2nd class device models in QEMU.  And I wonder if the effort isn't
> better invested in good v2v migration tooling instead of adding this
> to QEMU.
>
> I'm not strongly against VMware device models in QEMU, I do see the
> benefit too, but please explain what the plan here is.

While I can sort of understand where you're coming from, this does seem
to be inventing new patch acceptance criteria (which VMXNET3 authors have
to satisfy) that haven't generally existed / been applied to any other
device impl submission in the past. AFAICT, QEMU has welcomed / accepted
patches implementing pretty much any hardware device, provided the code
quality was acceptable.

Regards,
Daniel
-- 
|: http://berrange.com      -o-    http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org              -o-             http://virt-manager.org :|
|: http://autobuild.org       -o-         http://search.cpan.org/~danberr/ :|
|: http://entangle-photo.org       -o-       http://live.gnome.org/gtk-vnc :|