Urgh. Turns out that I had an xorg.conf that was just confusing enough for Xorg to fail to load the radeon driver. Now that I've got rid of that it autoloads radeon and everything is groovy.
** Changed in: xorg-server (Ubuntu) Status: New => Invalid -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xorg-server in Ubuntu. https://bugs.launchpad.net/bugs/1628744 Title: Modesetting picks incorrect card as output master To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/1628744/+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