Arch Linux

hungerfish

Member

Registered: 2009-09-13

Posts: 254

[SOLVED]Uefi + kms = garbled display, X broken.

I've been trying to get my new system up and running, it being new, I opted for an 'uefi-mode'-install.
My system is now configured, that rEFInd is run on startup, and from there I can select my kernel and boot it up (via efistub).

This works just fine, except that I have to disable KMS, or else I will get a blank screen(some flashing text is faintly visible on the top line of the display during boot).
If I configure X to automatically start, I get a totally garbled display(very pink). Depending on the combination of kernel options(passed via efistub) the screen also flashes.

Providing nomodeset solves the problem to a somewhat dis-satisfactory degree, as then the video driver refuses to work for X. I must force the use of the vesa driver, which sucks.

So,
freshly installed system(09.08.12), kernel 3.4, the radeon driver(xf86-video-ati). my card is a radeon 6850hd (northen island,barts I think).

Options and effects:
I always pass add_efi_memmap

video=efifb:off          -> no flicker/flashing, display still unusable.
video=radeondrmfb  -> flickering/flashing, kernel log reports "fb: conflicting fb hw usage radeondrmfb vs EFI VGA - removing generic driver"
nomodeset             -> display works fine, display mode is that of uefi(my case 1024x768), native mode would be 1280x1024. X fails, force vesa as a workaround.
radeon.modeset=0  -> same as above.

I think this may be a big fat bug

Any Ideas?

EDIT:
I've upgraded to 3.5.1-1-ARCH from testing, and the problem still persists. I'm now trying 3.6-rc1 but thats just freezing at boot atm.
UPDATE:
I found this pull request and today tried 3.6.0-rc3 straight form kernel.org
I can now startx with the radeon driver, and have full direct rendering and no distortions. I sadly get no output to the console during boot, the screen just turns off.
I'm marking this as solved, because I think this could just be down do misconfiguration in the kernel.

Last edited by hungerfish (2012-08-23 10:13:55)

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