https://bugs.freedesktop.org/show_bug.cgi?id=26891

--- Comment #3 from Jérémy Lal kapouer@melix.org 2011-05-16 13:27:40 PDT --- I'm booting an imac12,2 in UEFI mode (need a "Run EFI in physical mode" patch before doing so), here's how : 1) boot from latest ubuntu live CD (hold alt, or c, at boot) 2) dump the bios dd if=/dev/mem of=vbios.bin bs=65536 skip=12 count=1 3) move it to your partition's /lib/firmware/radeon/vbios.bin 4) use your patch, but move the radeon_read_bios_from_firmware call before all other calls to get the bios (force using vbios.bin)

That's it and thank you :)