[ovs-dev] [PATCH V4 2/2] netdev-dpdk: vHost IOMMU support

[Jan Scheurich]

> > Would the virtio PMD bug in DPDK 17.11 in the guest actually be
> > mitigated by running DPDK 17.05 or a fixed 17.11.1 as vhostuser backend
> > inside OVS on the host?

> [Mooney, Sean K] from talking to mark about this eairlier I don’t belive so.
> I think if you used 17.11 testpmd in the guest with kernel ovs you should
> get the same behavior e.g. it does not forward packet. The guest should not
> be able to know with certainty what vhost backend is in use on the host.

If that is the case why should OVS even consider documenting that there are known problems when running a DPDK 17.11 application in a guest, irrespective of the OVS version or datapath?

If anything, this is a critical DPDK bug and DPDK need to warn their virtio PMD users not to use 17.11 until this bug is fixed in a 17.11.1 maintenance release.

The real issue I see is that OVS-DPDK may also be deployed in in a VM with virtio ports, and that kind of deployment will indeed be broken with DPDK 17.11. Can we accept and document that as a limitation in OVS 2.9 that will be fixed in OVS 2.9.1 as soon as DPDK 17.11.1 is out?

Or should we as a temporary solution apply a patch to DPDK 17.11 to fix this when building OVS?

BR, Jan