[Libvir] PATCH: Support NIC model selection for QEMU/KVM

Daniel Veillard veillard at redhat.com
Wed Oct 31 15:21:26 UTC 2007

On Wed, Oct 31, 2007 at 03:05:07PM +0000, Daniel P. Berrange wrote:
> On Wed, Oct 31, 2007 at 09:34:33AM -0400, Daniel Veillard wrote:
> > > Getting it fixed upstream might be best.  We could also just have
> > > libvirt always append "model=rtl8139", but I'd be concerned that we
> > > could break existing VMs for some users if we swap out the network
> > > card unexpectedly.  An upstream change would have the same problem.
> > > 
> > > Regardless of what the defaults are, I don't think exposing a knob
> > > that lets you control what NIC the guest sees is that much of a hack;
> > > describing the guest hardware is what the config xml is mostly for.
> > 
> >   Agreed. The specifics of the hardware configuration emulated for the
> > domain have their place in the XML file. But I'm not sure what other 
> > compatibility issues may arise if we applied such a patch.
> >   Also I hate seeing a patch rot in the list archive without proper process
> > but I don't feel like I understand all the issues at stake here to really
> > try to apply it myself ...
> Having thought about it, I think its reasonable to aply some variant of
> this patch. Guest a question of how we want to present it as XML. Just to
> present some variants...
>    <interface type="bridge">
>       <nic model="rtl8139"/>
>       <source bridge="xenbr0"/>
>       <target dev="vif1.0"/>
>    </interface>
> I guess I'd lean towards the first variant, which was Jim's original
> suggestion.

  yes, I prefer that one too

> Of course for any of this to solve Jim's problem, we need virt-install
> and / or  virt-manager to explicitly ask for the RTL8139 nic when
> creating new guests, otherwise you're still at the mercy of the underlying
> default NIC choice in QEMU/KVM/XEn which may or may not be RTL8139.

  Well at least <nic .../> can be added after creation to guarantee the
profile won't change if the default gets eventually changed.


Red Hat Virtualization group http://redhat.com/virtualization/
Daniel Veillard      | virtualization library  http://libvirt.org/
veillard at redhat.com  | libxml GNOME XML XSLT toolkit  http://xmlsoft.org/
http://veillard.com/ | Rpmfind RPM search engine  http://rpmfind.net/

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