Comment 1 for bug 1713590

This is cause by trying to use sriov passthorugh on a host that does not support hardware offload of ovs.

the work around is to list the sriovnic agent before ovs in the ml2 conf.

e.g. change /etc/neutron/plugins/ml2/ml2_conf.ini form
[ml2]
...
mechanism_drivers = openvswitch,sriovnicswitch

to

[ml2]
...
mechanism_drivers = sriovnicswitch,openvswitch

you might want to also make sure that supported_pci_vendor_devs
in the ml2_sriov section does not contain the vendor id and product id of
the vf used for ovs offload. this will ensure that the sriovnic agent will
only manage interfaces that do not require ovs configuration.

if you had a nic that supported ovs offload and it is enable then doing a pci
pass through of the device without os-vif plugging the nic woudl resulst in a broken
dataplane hence the reason from removing them from the supported_pci_vendor_devs.

there is still a bug in os-vif here where we should first check the file exits before trying to use it so we should still harden the code. so lets keep this open to track that.