Ubuntu's Mir plans cause divisions
Ubuntu sponsor Canonical plan to switch the distribution to the company's Mir display server sooner rather than later and this move is now causing disturbances within the wider Ubuntu ecosystem. This appears to be especially so with the developers of two of the official Ubuntu remixes, Lubuntu and Kubuntu.
An initial post on the Lubuntu blog that said the remix would be adopting XMir, the X compatibilitiy layer for Mir. But that post was then withdrawn and replaced by a categorical statement that their project will not use Canonical's display technology. Lubuntu lead developer Julien Lavergne explains this decision in a mailing list post, saying that the expected performance decrease when running X.org applications on Mir via the XMir emulation layer is unacceptable for the lightweight distribution. Lubuntu's current plan will be to ship X only for 13.10 and 14.04 and look, in the future, to XMir support.
Other discussions over Kubuntu's position on XMir also took place on Google+ over the weekend. In the comments to a post by Kubuntu developer Martin Gräßlin, Ubuntu Community Manager Jono Bacon, Gräßlin and KDE desktop lead Aaron Seigo debated the merits of the XMir approach. Canonical wants to switch to a Mir-based graphics stack for Ubuntu with Ubuntu 13.10, the next version of the distribution with an eye to seeing the Mir stack more intensively tested.
Since few applications on the Linux desktop have been converted to Mir, the Ubuntu developers want to use XMir to run native X.org applications on top of their display stack. XMir is a port of the X.org server converted to use Mir calls to render the display, which Canonical hopes will provide a transitional stepping stone for X applications.
The upstream KDE developers, however, have made clear that they eventually want to switch to the competing Wayland solution and Kubuntu will follow suit. But as far as Gräßlin and Seigo are concerned, the switch is still a while away and KDE and Kubuntu plan to support both X.org and Wayland. As Gräßlin puts it: "We plan to continue to support X11 and Wayland for quite some time there is no need to rush. Our users will be able to choose."
With pushback from Kubuntu, Lubuntu and the upstream KDE project, Canonical's planned transition is becoming more complex and could see the main Ubuntu distribution isolated from its remixes and derivatives. It is currently unclear how these derivatives will proceed when Ubuntu stops supporting the X.org server as a fallback option.