Ubuntu Still Aims For Wayland System Compositor

While there's still more than one month until the Ubuntu 12.10 feature freeze, Canonical/Ubuntu developers continue to work towards their concept of having Wayland serve as a system compositor for this next Ubuntu Linux release due out in October, but will they make it?

For Ubuntu 12.10 at the UDS Oakland event the developers at Canonical set out with some ambitious plans for Wayland.

Canonical's plans involve using a Wayland-based compositor to control display outputs from boot to shutdown. Their intention with this system compositor is to provide smooth transitions during the boot process and for session switching and other operations, avoiding traditional VT switching, providing a consistent monitor layout, using the greeter as the lock screen, ensuring that locked sessions are actually secure from displaying, and showing the greeter while the session loads.

As I wrote back in May, "For Ubuntu 12.04 LTS they tried for a Wayland preview and weren't even able to achieve that for the Precise Pangolin. As someone that's been monitoring Wayland for the past five years and the first person to publicly write about Wayland when it was still a very young and experimental project by Kristian, I just don't see this system compositor goal coming close to fruition with Ubuntu 12.10. I've been saying for a while now that it will probably not be until Ubuntu 13.04 that Wayland takes on any really usable form."

We're now past Ubuntu 12.10 Alpha 2 and there's no integration of Wayland by default within Ubuntu "Quantal Quetzal", but the developers are still working on it.

There remains the system compositor blueprint where the item is a "high" priority that's been "started" and followed by many individuals. The work items that are still open on this Launchpad Blueprint include talking with the kernel team about VT switching, updating LightDM, using the greeter as a lock screen, implementing an Xserver signal hook to fake VT switch for input drivers, patching XWayland to use regiular input DDX drivers, figuring out how to minimize the changes between the different boot systems, talking with QA about testing, writing a Wayland back-end for Plymouth, and documenting the display manager / system compositor interactions. There's still a lot TODO in a very short amount of time.

The only completed tasks from this system compositor blueprint is evaluating whether to fork Wayland's Weston or provide additional functionality via a Weston plug-in and providing XWayland support for Nouveau.

While the XWayland support for Nouveau is marked as "DONE", that support isn't yet merged to mainline and just on Wednesday there was a v2 patch by Canonical's Christopher James Halse Rogers still working on the XWayland Nouveau support.

They're dedicated towards migrating in the direction of Wayland, but I still don't see this becoming a reality in Ubuntu 12.10. They may finally have Wayland as a technical preview, which they tried (but failed) to do for Ubuntu 12.04 LTS, except their goals probably won't be realized in full until 2013.

Whenever the Wayland system compositor for Ubuntu does materialize, there will still be fall-backs as the AMD Catalyst and NVIDIA binary Linux graphics drivers will not work. The initial implementation also won't rely upon desktop applications running directly on the Wayland compositor but rather via XWayland until the desktop environments and key applications fully support this new display technology.

While Ubuntu wants to be the first major distribution shipping a Wayland environment, they still aren't a main contributor to upstream Wayland/Weston. The current Ubuntu compositor work can be found in the separate RAOF/weston repository.