After applying updates from the wily-proposed repo, I can now boot into 15.10, kernel 4.2-17 with fglrx-updates.
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Broadway XT [Mobility Radeon HD 5870] -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1493888 Title: FGLRX incompatible with gcc 5 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-release-notes/+bug/1493888/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs