[libvirt] configuring a disconnected <interface>

[Laine Stump]

On 07/02/2013 04:07 PM, Dan Kenigsberg wrote:
> On Mon, Jun 24, 2013 at 11:22:16AM +0100, Daniel P. Berrange wrote:
>> On Sun, Jun 23, 2013 at 03:34:06PM +0300, Dan Kenigsberg wrote:
>>> On Fri, Jun 21, 2013 at 04:31:53AM -0500, Daniel P. Berrange wrote:
>>>> So I'm not inclined to support this disconnected mode.
>>> Disconnected mode exists in actuality. It has valid use cases in the
>>> virtual world as well. I would like to discuss the domxml schema for
>>> representing it, and then, hopefully find the menpower to implement it
>>> outside the core libvirt team. So please, reconsider.
>> The XML schema is easy enough - it is just a new  <interface type=none>.
>> Ideally we would want some kind of support in QEMU for this, concept
>> so that we don't have to have a hidden dangling tap device
> That would be cool indeed. It would make it possible to
> virDomainUpdateDevice() from a tap-based connectivity to non-tap one.
>
> Until we have something like that in qemu, would it be reasonable to
> implement <interface type=none> via a dangling tap? Wouldn't it be fine
> to limit changing type=none to type=network only to bridge-based
> networks?

Well, that *is* how virDomainUpdateDevice behaves when switching from
one network connection to another - if the source and destination are
both implemented with tap, it works, otherwise it returns
OPERATION_UNSUPPORTED.