Thanks! Unfortunately, I am running into the following issue when attempting to use the generic ethernet configuration:

$ virsh -c qemu:///system create /tmp/generic.xml
error: Failed to create domain from /tmp/generic.xml
error: internal error process exited while connecting to monitor: kvm: -netdev tap,id=hostnet0: could not configure /dev/net/tun: Operation not permitted
kvm: -netdev tap,id=hostnet0: Device 'tap' could not be initialized

This is the network part of my xml file:

<devices>
   <interface type="ethernet"/>


 ...
  <devices>
    <interface type='ethernet'/>
    ...
    <interface type='ethernet'>
      <target dev='vnet7'/>
      <script path='/etc/qemu-ifup-mynet'/>
    </interface>
  </devices>
  ...


In my /etc/libvirt/qemu.conf file I have the following set:

user = "root"
group ="root"
dynamic ownership = 0
clear_emulator_capabilities = 0
cgroup_device_acl = [
    "/dev/null", "/dev/full", "/dev/zero",
    "/dev/random", "/dev/urandom",
    "/dev/ptmx", "/dev/kvm", "/dev/kqemu",
    "/dev/rtc", "/dev/hpet",
    "/dev/net/tun",
]

I am running Ubuntu 12, which does not use SELinux.


On Fri, Aug 9, 2013 at 8:01 AM, Daniel P. Berrange <berrange@redhat.com> wrote:
On Thu, Aug 08, 2013 at 08:55:27PM -0600, Joshua McKee wrote:
> Hi,
>
> I hope this is the right place to ask this question. I was wondering if
> there is a way to set up a KVM VM using an XML document as input into Virsh
> that uses bridged networking over a wireless card.
>
> I understand that wireless cards to not natively support, but I was able to
> find a working solution here:
> http://blog.ericwhite.ca/articles/2011/04/creating-a-wireless-bridge/.

Ok, that's slightly different. The traditional integration with Linux
bridge devices is doing ethernet layer bridging - so all protocols
like IPv4, IPv6, etc, etc will "just work".

What that blog describes is protocol layer bridging, which with those
instructions only works for IPv4.

Libvirt doesn't have any explicit support for the latter. Though we have
thought about implementing it in the virtual network APIs, we've never
got around to it.

> The issue is, I can use this bridge by calling KVM directly. However, I
> cannot figure out how to get this same configuration on an XML file that I
> input into Virsh for the creation of a VM.
>
> My understanding is that libvirt calls KVM/QEMU at some point, but I may be
> mistaken.

You might be able to get it working using the generic ethernet config

   http://libvirt.org/formatdomain.html#elementsNICSEthernet

That setup you specify a pre-created TAP device for the VM to use.
Of course it is upto you todo the manal config steps described in
that blog, so is more tedious from an admin pov.


Daniel
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