https://bugs.freedesktop.org/show_bug.cgi?id=26891
--- Comment #7 from shirk@bitspin.org 2011-05-19 03:30:41 PDT --- (In reply to comment #3)
I'm booting an imac12,2 in UEFI mode (need a "Run EFI in physical mode" patch before doing so), here's how :
- boot from latest ubuntu live CD (hold alt, or c, at boot)
- dump the bios dd if=/dev/mem of=vbios.bin bs=65536 skip=12 count=1
- move it to your partition's /lib/firmware/radeon/vbios.bin
- use your patch, but move the radeon_read_bios_from_firmware call before all other calls to get the bios (force using vbios.bin)
Thats exactly what I did on my MBP however the screen flicker remains..
I'm pretty sure the BIOS is valid (dmesg identifies it as ATOM BIOS: Apple) and strings revealed data like "Whistler Pro" which IIRC is the type code used by the Radeon HD 6xxx series.
Since Jérémy has a working setup with GPU acceleration I can only suspect a problem in the microcode. iMac12,2 has a Radeon HD 6970M which utilizes the CAYMAN microcode while my Radeon HD6750M is using TURKS.
So I'm stuck with working but non-accelerated radeondrmfb.