After three decades of life, Unix’s X Window display server is showing its age and Ubuntu Linux creators have decided enough is enough. In order to power the Unity user interface in Ubuntu on tablets and phones, Canonical says that the 1980’s-era X Windows display server has to go and in its place we will find “Mir”, Canonical’s custom-build display server which Canonical describes as “a system-level component targeted as a replacement for the X window server system to unlock next-generation user experiences for devices ranging from Linux desktop to mobile devices powered by Ubuntu.”
Canonical explained in a blog post on their site:
Today Unity (the rendering part of it) runs as a plugin in Compiz which sits on top of X and is a recurring source of frustration on the developer-, design- and finally also on the user side as a lot of our ideas (handling a mufti-monitor setup in 12.04 or our plans for menu bars come to mind) require quite some intrusive changes to the underlying system. Regardless of how carefully crafted the solution, it is bending a stack to something that it wasn’t necessarily designed for. Bend over backwards too much and you will fall on your back, bugging users with nasty bugs, regressions, unexpected behavior and plenty more that drives the frustration level up.
While evaluating our options, looking at extending the current stack to our needs, using the Wayland protocol (or any of its implementations) and comparing that with our designs & ideas we concluded that neither approach would allow us to do what we want in the quality that we would like to see for Ubuntu & Unity (at cost and in time).
Plus, there is the rather sizable challenge of pulling Wayland/X onto a mobile device, working with SoCs on driver support, tuning this stack for power consumption and performance and dealing with other issues of a stack that hasn’t been designed for a convergence setup as we envision it. A lot of distraction from the actual goal, to provide an outstanding experience across all the supported devices – from consumer electronics to desktop computing devices to enterprise devices.
The chosen approach was to develop Mir, our own Display Server which is engineered driven by the designs and requirements that our larger vision dictates – no compromises, no crude hacks, fully testable & tested, performance in mind, support for legacy X applications, developed by Ubuntu for Ubuntu.