Supporting the OpenvSwitch datapath kernel module packages on Ubuntu 12.04 whilst ensuring compatibility with the hardware enablement kernels that we push out for each point release has been challenging; the patch set I had to implement on top of 1.4.0 to support the Quantal 3.5 kernel was not insignificant!
The upstream provided datapath kernel module is important for OpenStack users as it provides support for overlay networking using GRE tunnels which is used extensively by Neutron for separation of Layer 2 tenant networks. Right now the native kernel module does not support this feature (although that is being worked on – hopefully for 14.04 we can drop the datapath module provided by upstream completely).
For the Raring 3.8 kernel that will ship with the Ubuntu 12.04.3 point release we are taking a slightly different approach; instead of patching the hell out of the 1.4.0 OpenvSwitch datapath module again, we will be providing specific packages for the Raring HWE kernel.
If you currently use the openvswitch-datapath-dkms module and want to switch to the Raring HWE kernel then you will need to take the following action:
sudo apt-get install openvswitch-datapath-lts-raring-dkms
There is also an equivalent openvswitch-datapath-lts-raring-source package for users of module-assistant. These packages are based on the 1.9.0 release of OpenvSwitch that we have in Ubuntu 13.04 which provides full compatibility with the 3.8 kernel.
The userspace tools and daemons, openvswitch-switch for example, are compatible with later datapath module versions so these won’t be upgraded.
These updates are currently in the precise-proposed pocket undergoing verification testing in preparation for release alongside Ubuntu 12.04.3 – see bug 1213021 for full details if you would like to help out with testing.