[libvirt-users] Cannot get interface MTU - qemu quest fails to start off OpenVswitch

[Michal Privoznik]

On 5/10/19 6:23 PM, lejeczek wrote:
> On 10/05/2019 14:44, Michal Privoznik wrote:
>> On 5/10/19 3:26 PM, lejeczek wrote:
>>> hi guys
>>>
>>> I have a qemu guest and openvswitch bridge and the guest fails to start:
>>>
>>> $ virsh start work8
>>> error: Failed to start domain work8-vm-win2016
>>> error: Cannot get interface MTU on 'ovsbr0': No such device
>>
>> Well, this means that 'ovsbr0' doesn't exist. Is that so? Can you
>> share your <interface/> configuration and the network XML?
>>
>> Michal
> 
> so if your libvirt's net is like this:
> 
> <network>
>    <name>ovs-br0</name>
>    <uuid>e5129e76-1576-4866-97e1-42f14263cfc2</uuid>
>    <forward mode='bridge'/>
>    <bridge name='ovsbr0'/>
>    <virtualport type='openvswitch'/>
> ....
> 
> then you need extra(extra for ovs tools create both for us at bridge
> creation time and nmcli(you) need to create those explicitly) port+iface
> so this:
> 
> $ ovs-vsctl show
> 
> output will contain this:
> 
> ...
> 
> Port "ovsbr0"
>              Interface "ovsbr0"
>                  type: internal

That is expected. <forward mode='bridge'/> is document like so:

https://libvirt.org/formatnetwork.html#elementsConnect

Michal