Ubuntu To Use Its Own Display Server Called Mir, Unity To Be Ported To Qt/QML

According to a recent announcement, Ubuntu will use its own Display Server called Mir, replacing X Window server. The reason Ubuntu will use its own display server is that "none of the existing solutions would allow us to implement our vision without taking major compromises which would come at the cost of user experience and quality" and obviously, to achieve full "convergence", a hot topic recently that has caused quite a bit of controversy.

Mir, a display server that works across desktop and mobile devices

Mir (as in the space station) will provide a graphics stack that works across different platforms and it will firstly replace SurfaceFlinger for the Phablet images and will eventually make it on the desktop.

There will be two Mir libraries: a server which will contain the server side components and will be used to implement a compositor and a client which will allow applications to communicate with Mir servers (used by toolkits). There are also going to be Qt bindings for Mir, an Unity System Compositor, a new Unity greeter implementation using Mir and Unity.

Also, Mir will support multiple GPUs running in the same system. The MirSPec page mentions that it should support seamless transition between GPUs so maybe with this we'll finally get proper Optimus support on Linux.

Initially, Mir will only run if your system uses the free / open source drivers, but Canonical is in talks with GPU vendors to get Mir support for those drivers / GPUs:

With our X-integration in place, you can run Mir on your desktop machine if your system runs a GPU that supports the free driver stack. For the closed-source desktop drivers: We are in active conversations with GPU vendors to enable Mir on those drivers/GPUs, too. More to this, we are working towards a more unified driver model sitting on top of EGL.

- Thomas Voß, Canonical Technical Architect

If you're wondering what will happen to existing applications that require X, Mir has that covered and it will come with support for legacy X applications. Furthermore, there's no need of porting XUL and GTK3 (and obviously, Qt/QML) applications because the Ubuntu developers will work on providing Mir integration for these toolkits.

Unity to be ported to Qt/QML

The second big announcement of the day is that Unity will be ported to Qt/QML "to make development more efficient across our wider convergent strategy".

According to the Unity Next Spec, Unity Next will be integrated on top of Mir, the UI will use Qt and will use much of the code that's already available in the Ubuntu Touch Developer Preview. The ultimate goal is to provide a seamlessly scale across multiple form factors and carry Unity's visual design and identity. This means Unity on the phone, tablet, TV and desktop will share the same code base, so the "convergence" Mark Shuttleworth has talked about a while back is starting to take shape.

With the recent Ubuntu Touch announcements, this makes sense, but there is something that I don't understand: why was Unity 2D, which is written in Qt/QML, dropped from Ubuntu and they've used the Compiz-based Unity on the desktop instead? And what's going to happen with the Compiz-based Unity? I just hope this isn't another rushed decision, like the recent changes to UDS which is now an online only event and the rolling release proposal that even Ubuntu members were surprised to hear about.

I'm also starting to doubt that Lubuntu, Kubuntu or Xubuntu will continue to exist after so many changes: rolling release, new display server, focus on Ubuntu Touch, etc. At least, in their current form: based on Ubuntu. Using Debian on the other hand should be a lot easier so maybe they'll switch to it? I guess we should find that out soon, after the Lubuntu, Xubuntu and Kubuntu teams analyze their options.

The plan

The target is to have a first level/functional integration of Mir and Unity Next by May 2013, by October 2013 to have a Mir - UnityNext code base that could be taken to produce a phone and reach full convergence by April 2014 (Ubuntu 14.04 LTS).

More about Mir: https://wiki.ubuntu.com/MirSpec | Mir source code

More about Unity Next: https://wiki.ubuntu.com/UnityNextSpec

Mir and Unity Next will be discussed at the Ubuntu Developer Summit (which from now on will only take place online) which starts tomorrow.