This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/setting-up-x-in-nixos-with-amd-radeon-6800/11124/6

I just tested this and can report this works great.

Here's how I tested this branch:

I created an iso with this patch and flashed in on a usb flash drive

git clone --depth=1 https://github.com/afontaine/nixpkgs.git -b enable-rx6000-gpus
cd nixpkgs/nixos
nix-build -A config.system.build.isoImage -I nixos-config=modules/installer/cd-dvd/installation-cd-graphical-plasma5-new-kernel.nix default.nix
# identify the usb drive
sudo lsblk -o NAME,MODEL | grep Flash
# FLASH_DRIVE=/dev/sdd
ISO=result/iso/nixos-21.03pre-git-x86_64-linux.iso
sudo dd bs=1M if="${ISO}" of="${FLASH_DRIVE}" && sync

I booted on the flash drive

✔️ Unlike a similar build I made from master, this build would let the installer arrive until the plasma desktop.

I installed nixos using the flash drive

I just added the following to the configuration.nix file generated by nixos-generate-config:

{
  boot.kernelPackages = pkgs.linuxPackages_latest;
}

✔️ The resulting installation also booted fine and resulted in the plasma desktop being usable.

I switched the configuration to have the amdgpu driver used

After switching to this branch as a the nixos channel:

sudo nix-channel --add https://github.com/afontaine/nixpkgs/archive/enable-rx6000-gpus.tar.gz nixos
sudo nixos-channel --udpate

And extending the configuration.nix file to contain the following:

{
  boot.kernelPackages = pkgs.linuxPackages_latest;
  boot.initrd.kernelModules = [ "amdgpu" ];
  services.xserver.videoDrivers = [ "amdgpu" ];
  hardware.opengl = {
    enable = true;
    driSupport32Bit = true;
  };
}

✔️ The amdgpu driver was correctly used:

sudo inxi -G
Graphics:  Device-1: Advanced Micro Devices [AMD/ATI] driver: amdgpu v: kernel 
           Display: x11 server: X.org 1.20.10 driver: loaded: amdgpu note: n/a (using device driver) 
           resolution: <missing: xdpyinfo> 
           OpenGL: renderer: AMD SIENNA_CICHLID (DRM 3.40.0 5.10.11 LLVM 11.0.1) v: 4.6 Mesa 20.3.3

@kimat With this patch, you should no longer need the boot.kernelPatches configuration, as that is the purpose of the patch 😉

If that's not the case, let me know 👍 My current configuration no longer contains the patch configuration.

This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/prs-ready-for-review/3032/455

This rebuilds a lot of kernels. Maybe it should go through staging?

This rebuilds a lot of kernels. Maybe it should go through staging?

Sure @SuperSandro2000! Do I target staging or staging-next?

@afontaine, I just updated my pervious comment to showcase how I correctly tested this branch, with success, now.

This rebuilds a lot of kernels. Maybe it should go through staging?

Sure @SuperSandro2000! Do I target staging or staging-next?

staging is correct here.

@kimat that is great to hear 👍 glad everything is working