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Ubuntu Building Own Display Server, Unity To Switch to Qt/QML

Canonical has today publicly confirmed that they are working on a new cross-platform displayer server for Ubuntu.

Called ‘Mir‘, the X Window Server replacement is tasked with ‘enabling development of the next generation Unity’. Which, in yet another about-turn, is to be rebuilt in Qt/QML.

The news isn’t much of as surprise. Earlier this year Canonical’s Jono Bacon made several remarks in a Q&A session that hinted at the possibility of an alternative display manager.

’’…The simple reality is that X doesn’t meet those needs, Wayland doesn’t meet those needs.’

From looking at the commit log for Mir this opinion has been held since June last year, which is when work on Mir appears to have begun.

Why Mir?

When Mark Shuttleworth set out his grand goal of Ubuntu being ‘convergent’ – running across mobiles, tablets, desktops and TVs – he also threw down a series of technical hurdles that would first have to be overcome. One of the steppest to clear was always going to be the choice of display server – the the part of the system that draws the UI, and user interaction with it, on screen.

Currently Ubuntu uses X.

X is efficient at doing what it does but it has a problem: it is built upon code that’s almost 30 years old. A mature code-base brings with it legacy support for features and functions that are no longer needed on modern desktops, much less phones and tablets.

Intending to address this is Wayland – a relatively new display protocol that integrates features (like compositing) directly into the display server rather than adding them on as an afterthought.

The choice facing Canonical was to adapt one of these existing display server technologies/protocols to work across form factors, but compromise on vision, or create their own one from scratch.

Canonical chose the latter., with Mir built specifically to meet the aims and goals of Unity.

Task Ahead

The big task for Canonical going forward will be to persuade GPU vendors to invest in and support Mir.

Canonical say that they are ‘in contact with [and] working closely’ with graphics chips makers to support Mir and, perhaps more interestingly, ‘…distill a reusable and unified EGL-centric driver model that further eases display server development in general and keeps cross-platform use-cases in mind.”

But for now Mir is only able to run atop of free graphics drivers.

When Will It Arrive?

From the Mir Spec on the Ubuntu WIki, Mir is intended to replace SurfaceFlinger, the Android display server used in the Ubuntu Touch images, at some point in the near future. with the desktop targeted after that.

There is a Staging PPA for Mir is also available.

Around May this year we should see the first useable demonstration of Mir with Unity Next (the ‘new’ Qt/Qml version of Unity) on Ubuntu Touch.

By April 2014, the date of the next LTS release, Canonical hope to achieved full convergence, with Mir and Unity Next running across all platforms.

For more information on Mir head to the Ubuntu Wiki.

Mir Specification