I previously said it was working in 12.04, but that was because it was using the VESA driver and not radeon. I did try the latest snapshot of tasty 14.04 and xorg started without issues, so this bug can be closed.
I also found the following which is the exact same bug: https://bugs.freedesktop.org/show_bug.cgi?id=68984 'Looks like your X server loads the "glx" module ahead of time by default, which is known to break glamor.' ** Bug watch added: freedesktop.org Bugzilla #68984 https://bugs.freedesktop.org/show_bug.cgi?id=68984 -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xserver-xorg-video-ati in Ubuntu. https://bugs.launchpad.net/bugs/1259049 Title: Xorg segmentation fault with AMD HD 7790 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-ati/+bug/1259049/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : [email protected] Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp

