Arch Linux

zekebsatx

Member

Registered: 2016-01-29

Posts: 72

imac four screen split when booting installation iso

I am trying to install Arch on an aluminum imac, but I am having trouble with a graphics issue.  I am able to boot the installation iso.  After a very brief time where it looks normal, the screen splits into four panels each a mirror  of the others at very low resolution which is not really legible. 

After booting Arch, but not being able to read the CLI text, I used Antergos to install since I could find my way through their GUI at low resolution, but it has the same problem.  I was able to install it successfully, and the Antergos splash screen looks normal, and I can get to the GRUB editing features on their splash screen and that is normal, but if I boot, I see the message about clean nodes, and then the screen splits.  Just like with Arch, if I try to boot without X, I still get the four panel problem, so it doesn't seem like it is an X-specific (or driver?) problem.

Same issue if I try to boot the Fedora live ISO.

Here is a link to a post of Reddit with an image showing the problem (not my post):
Four screen problem

I tried to install CentOS 6.5 like the OP in the linked post, but the bootloader could not see the CentOS install media (same problem with Ubuntu).

It is able to see the media for Arch (Arch, Manjaro, Antergos) or Fedora isos.

Any ideas?

WorMzy

Administrator

From: Scotland

Registered: 2010-06-16

Posts: 13,570

Website

Re: imac four screen split when booting installation iso

I'm going to assume that you are trying to boot the Arch LiveCD. Try booting the liveCD with KMS disabled: https://wiki.archlinux.org/index.php/Ke … odesetting

If you are trying to boot your Antergos install, please seek support on the Antergos forums.

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zekebsatx

Member

Registered: 2016-01-29

Posts: 72

Re: imac four screen split when booting installation iso

Awesome!  That worked and I was able to install Arch. 
Now that I can actually read the output of lspci, I see that the graphics card is a Radeon HD4670

I installed xf86-video-ati, and per the wiki removed the nomodeset from the grub line, but upon reboot, it goes back into the four screen split.

How do I set the video driver properly so that I can use a GUI?

EDIT:  I also tried to add the "radeon" module to /etc/mkinitcpio.conf and then

# mkinitcpio -p linux

But the problem persists

Edit 2:
I found this thread -
https://bbs.archlinux.org/viewtopic.php?id=188561

Looks pretty bleak.  I don't have a display port adapter, so I can't test with the adapter in.  Not sure it is worth the trouble to downgrade and install the legacy driver from AUR?

Maybe someone in this subforum has a workaround that the OP above never tried?

Last edited by zekebsatx (2016-01-29 22:08:29)