Comment 0 for bug 1620407

Ubuntu 16.04.1 LTS (amd64)
libvirt-bin 1.3.1-1ubuntu10.1

We use external scripts to setup tap interfaces, e.g.

    <interface type='ethernet'>
      <mac address='52:54:00:18:0d:a3'/>
      <script path='/etc/libvirt/14v/mf_testet.sh'/>
      <target dev='mf_testet'/>
      <model type='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </interface>

Starting the VM throws an error message ("interface not found" or something like that).

IIUC, the script invocation is done by qemu, so the interface
may not yet exist when libvirt is constructing the qemu cmd args.
Checking for that interface in advance therefore is a bug.

Attached patch skips the check if a <script> parameter is provided.

Regards
Matthias Ferdinand