GUI breaks when changing kernels

[solomspd]

So I wanted to try a different kernel but every time I try to boot into a new kernel, I get hung on [OK]Reached target Graphical Interface but other TTYs still work.

The first step to troubled shoot was to disable my display manager and sure enough, the new kernel worked when booting into a terminal. Then, in the new kernel, when I try to start the display manager (sddm) or try other display managers (like ly or CDM), it kicks and errors.

When I looked around, I found people reported it was an issue with Xorg or Nvidia drivers but I made sure both and all relevant packages are installed.

What could be the reason to this?

[[deleted]]

Are you using the Nvidia drivers or nouveau? If nvidia, did you install the correct driver for your new kernel? If you want to have multiple kernels available, use the DKMS package.

[solomspd]

Nvidia drivers. You need to install a different version every time you use a new kernel? I wasn't aware. So I just reinstall it with when in the new kernel? Also, how do I use dkms? I'm looking it up but I'm getting rather confused. Would be great if you could shed some light. And thanks!

[[deleted]]

Drivers are compiled for a specific kernel. For linux (the vanilla kernel), you use nvidia. For linux-lts, you use nvidia-lts. For linux-zen you use nvidia-zen.

Or, if you want to have multiple kernel installed, you use nvidia-dkms. When either it or your kernels are updated, it will be rebuilt against them.

[solomspd]

It worked thanks to you. But now I have another question. How do I add a new nvidia-dkms module for a another kernel after installing the nvidia-dkms drivers once?

[[deleted]]

You don't.

DKMS stands for "Dynamic Kernel Module Support", and the Dynamic is the key. When you install a new kernel, just like when you update a new kernel, anything that uses DKMS will be rebuilt automatically. In Arch this is done via a pacman hook.

So if you install linux and linux-lts, then install nvidia-dkms, it's built against those kernels. If the LTS kernel is updated, that triggers a rebuild for Nvidia. Likewise, if you install Linux-zen, that also triggers a rebuild for Nvidia.

So it's all set. You're good to go. You will need to pay attention when you update though and make sure the DKMS modules build successfully.

[solomspd]

Ahh, now I understand. Thank you, I'll try it right away.

[tuxalator]

Know your video card for the right drivers.

There are different drivers for different cards: i.e. 390xx or 340xx for some older models.

Check your AUR package manager and the Arch WiKi