Here's how to have radeon drm working (on imac 12,2 27" screen) : boot from latest ubuntu live CD for amd64.
Booting from CD is done in BIOS mode. There seems to be a way to set BIOS mode for booting on hard disk, too, since bootcamp does this to start windows. Booting in EFI mode from hard disk is triggering (at least) two bugs : 1) kernel use something called EFI virtual mode, and it's broken on that machine, search for "run efi in physical mode" patch. It won't boot without it, and gives a a black screen too. 2) https://bugs.freedesktop.org/show_bug.cgi?id=27314 screen goes black, but everything else work, X is even successfully starting, and recognize radeon in DRI2 mode. ** Bug watch added: freedesktop.org Bugzilla #27314 http://bugs.freedesktop.org/show_bug.cgi?id=27314 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/542660 Title: New Apple iMac (Core i5) fails to display anything -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
