Ovs error when starting vm: ovs-vsctl: 'del-port' command requires at least 1 arguments

[Michal Prívozník]

On 30. 3. 2020 11:10, Thomas Pircher wrote:
> Hi,
> 
> my system got updated to libvirt 6.0.0 (from 5.6.0) this morning, and
> now I'm having problems starting VMs that make use of openvswitch
> portgroups.

I don't see any changes between 5.6.0 and now done to openvswitch in
libvirt (apart from harmless code reworks towards glib).

> 
> When I start a VM, I get this error message on virsh:
>> virsh # start testvm
>> error: Failed to start domain testvm
>> error: An error occurred, but the cause is unknown

I suspect this is the problem. Something fails during startup (I think
it's creating the TAP device which fails) and later, when clearing up
then NULL is passed as "generated" TAP device name. But this is just my
guess, because I'm unable to reproduce.

But in order to confirm, we need to trace the domain command line
generation process. Can you attach debugger to libvirtd, set a break
point on virNetDevTapCreateInBridgePort() and step through it to find
which function fails, please?

Can you please turn on debug logs and share them?

https://wiki.libvirt.org/page/DebugLogs

Michal