Fedora 22 KDE Plasma Desktop Spin and the Open Source radeon Driver

I’m not sure if everyone will experience this or if it was something I did incorrectly during installation, but I noticed the following error in the kernel ring buffer:

[drm:radeon_init [radeon]] *ERROR* No UMS support in radeon module!

And I found myself staring at a 1024×768 resolution display which was unchangeable in that regard and refused to recognize the second monitor beyond mirroring the display to it.

The solution is to simply remove the “nomodeset” option from your kernel arguments.  To fix it temporarily and prove the solution works, simply use the ‘e’ key at the GRUB boot menu, find the line that begins with “linux”, and delete the word “nomodeset” in the line.  Then press Ctrl+x to boot.  Your machine should be a lot prettier now if you rely on AMD graphics.

To fix this permanently, simply modify /etc/default/grub so that the line that begins with “GRUB_CMDLINE_LINUX=” no longer contains the word “nomodeset.”  Save your changes.  If your machine boots via EFI, use the following command to create the new grub.cfg file and put it in the right place:

grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg

If you don’t yet use EFI, execute the following:

grub2-mkconfig -o /boot/grub2/grub.cfg

At least my machine is usable until I figure out the fglrx issue…or until AMD just releases 15.20 as a general Linux implementation.

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2 Responses to Fedora 22 KDE Plasma Desktop Spin and the Open Source radeon Driver

  1. fred says:

    How did you install the open source radeon driver? all my searches for radeon lead me to fglrx and anything radeon seems to say it should be automatically installed so no one tells you how to do it in fedora 22

  2. Felix says:

    Thank you soooo much! Before reading your guide I experienced some issues with the screen’s background-light and things like closing the notebook-lid had no effect at all… (Lenovo B50-45)

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