[libvirt] [PATCH] Xen: Add support for interface model='xenpv'

[Daniel P. Berrange]

On Thu, Nov 26, 2009 at 11:45:42AM +0100, Jiri Denemark wrote:
> Xen HVM guests with PV drivers end up with two network interfaces for
> each configured interface. One of them being emulated by qemu and the
> other one paravirtual. As this might not be desirable, the attached
> patch provides a way for users to specify that only paravirtual network
> interface should be presented to the guest.
> 
> The configuration was inspired by qemu/kvm driver, for which users can
> specify model='virtio' to use paravirtual network interface.
> 
> The patch adds support for model='xenpv' which results in type=xenpv
> instead of type=ioemu (or nothing for newer xen versions) in guests
> native configuration. Xen's qemu ignores interfaces with type != ioemu
> and only paravirtual network device will be seen in the guest.
> 
> A possible addition to this would be to force type=ioemu for all other
> models which would result in only emulated network device to be provided
> for an HVM guest on xen newer then XEND_CONFIG_MAX_VERS_NET_TYPE_IOEMU.
> No type would be configured when model is missing in domains XML.
> If you think this is a good idea, I'll prepare a second version of the
> patch.

Yes, but a slight variation - we need to maintain reasonable back
compatability so there are 3 cases to support

 - No model - use current behaviour which lets it setup both
 - xenpv  - use only PV nic
 - other model - use the requested emulated nic


Can you add a couple of test data files for this since its quite a
complex area of conversion - you'll see we've already got the 
sexpr2xmltest.c and xml2sexprtest.c and xmconfigtest.c for Xen

Regards,
Daniel
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