[libvirt] How to stop libvirt from deleting tap device after shutdown

Daniel P. Berrange berrange at redhat.com
Mon Mar 2 15:01:01 UTC 2009

On Mon, Mar 02, 2009 at 03:15:17PM +0100, Matthias Dahl wrote:
> Hi.
> I am currently setting up a new server machine which will host several kvm's 
> managed largely by libvirt. The network setup though is done prior to libvirtd 
> startup and shouldn't be touched by it.
> So currently everything works just fine with 0.6.0 except that libvirt deletes 
> the tap device after I shut a kvm machine down which is something I naturally 
> don't want. I looked through all the documentation I could find but I could 
> not come up with a solution.
> Forgot to mention: all kvm machine are connected through a tap device with no 
> bridge or whatsoever but 1:1 NAT. This done for performance reasons. As model 
> I use "virtio".

>     <interface type='ethernet'>
>       <mac address='52:54:00:25:6f:3f'/>
>       <script path='/bin/true'/>
>       <target dev='charon_pvnet1'/>
>       <model type='virtio'/>
>     </interface>

With type='ethernet'  libvirt doesn't have anything todo with TAP device
management, leaving it upto QEMU, and any script you configure. 
libvirt only creates/deletes TAP devices when using type=bridge or
type=network.  So I think it is probably QEMU itself that's killing off
your pre-created TAP device, rather than libvirt.

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