Mir will be the default display server for Ubuntu by October (13.10). http://www.jonobacon.org/2013/06/28/mir-in-ubuntu-13-10-benchmarking-and-more/ There will be a fallback for non-supported hardware to X11, so you'll probably be okay for a little while. But by April next year (14.04), they are going to remove that fallback. I hope you guys are starting to think about adapting your X11 driver to support the EGL "android style" driver model that Mir uses! https://wiki.ubuntu.com/Mir/