I figured it out. There is a new package "ubuntu-desktop-mir" that you also need to run mir.
However, I still have the flickering :( -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1233545 Title: XMir screen corruption on radeon GPU To manage notifications about this bug go to: https://bugs.launchpad.net/unity-system-compositor/+bug/1233545/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs