Fix AMD Radeon (Arch) Linux failed to start LightDM on boot

Background

I use Artix Linux as my workstation, which is based on Arch Linux and adopts Systemd-free approach. In my case, the init system is OpenRC.
My current machine is home-built using AMD Radeon as graphics card and GPU.

Problem

It always failed to start LightDM, a display manager, on boot, and just showed blank screen except a single underscore.
I had to:

1. push Alt + F4 to meet XDM console
2. enter login password
3. run startxfce4
4. enter password again

... every time🤒
Also, Fcitx hadn't worked well for every first boot recently.
It was inconvenient and uncomfortable.

Solution

I followed the Arch Linux documentation below and have become happy😃

• https://wiki.archlinux.org/index.php/Kernel_mode_setting#Early_KMS_start

First, I edited mkinitcpio.conf:

# nvim /etc/mkinitcpio.conf

to enable amdgpu module like this:

- MODULES=""
+ MODULES=(amdgpu)

Then I rebuilt initial ramdisk for Linux kernel:

# mkinitcpio -p linux

That's it. I have got along with LightDM ever since😊