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-X, which is subscribed to fglrx-installer in 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 _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp