I've tried to install the OpenCL part of amdgpu-pro 20.20 on Ubuntu 20.04 running on a Ryzen 3700X, and an Asus Radeon RX Vega 64 a number of times. Every time it installs all right, but when I restart Ubuntu, it hangs and fails to get to the login screen.
I've installed 20.20, and the latest 20.30, like so:
amdgpu-install --opencl=pal --no-dkms --headless
amdgpu-pro does support 20.04 now, so this works. However, it hangs after a reboot every time.
When I switch to a virtual terminal, uninstall amdgpu-pro, and reboot Ubuntu, it starts, and works normally.
It took quite some time, but I stumbled on a post claiming that disabling Wayland would allow Ubuntu to start normally. You can do this by setting WaylandEnable=false in file /etc/gdm3/custom.conf.
They say it has to do with Xorg, Wayland, and KMS, but I'm not sure what's causing the issue. Anyhow, it does work! However, you obviously can't start Wayland anymore.
They also said that you could solve this issue by modifying file /lib/systemd/system/gdm.service, and change the following line:
This is a bit of a workaround, but it works as well, and allows you start Wayland by selecting it on the login screen. However, it also displays a black screen for about 15 seconds while booting.
Is there a way to fix this issue, where you don't have to use these workarounds?