• NixOS on Radxa Rock 5B

#+begin_quote :warning: This is incomplete and untested! I take no responsibility for this. #+end_quote

This repo contains my opinionated infrastructure to run NixOS on the [[https://wiki.radxa.com/Rock5/5b][Radxa Rock 5B]]. It also provides a substituer (powered by Cachix) and it supports cross compilation.

** How to flash the eMMC

A no brain automatic flashing script is in progress, meanwhile:

#+begin_src sh

delete all partitions on /dev/sda (assuming it is the eMMC)

$ nix build .#uboot $ sudo dd if=result/shared.disk-image.img of=/dev/sda $ nix build .#rootfs

create a new partion /dev/sda2 in the remaining free space

$ sudo dd if=$(readlink result) of=/dev/sda2 status=progress

mark /dev/sda2 as legacy bootable (for example using fdisk advanced options)

#+end_src

I haven't tested (yet) booting from other devices but I heard of people being able to do so.

** Panfork

Mesa is overriden with [[https://gitlab.com/panfork/mesa][panfork]] by a Nix overlay, a panfrost fork supporting the Mail G610, another Nix module automatically loads the proprietary firmware blob (which is redistributed by this flake).

I've tried to rebuild Sway with it and it seems to work but I can't guarantee anything since it's not something that I use on this board. Softwares depending on Mesa need to be rebuilded then, personally I only use Kodi for now.

*** Kodi

I'll try to maintain a working Kodi supporting hardware acceleration. Unfortunately I couldn't override ~kodi~ from ~nixpkgs~ because of how the Nix code is written, many dependencies that I needed to change were hardcoded and not passed using the ~callPackage~ idiom.

I had to override ~ffmpeg~ and ~mpp~ with Rockchip forks. Unfortunately for ~mpp~ I had to use this [[https://github.com/martivo/mpp/commit/38afa760be814dbbf32019b6c588be8304c1e486][further fork]] (thanks @martivo). I also have to thank @amazingfate that guided me in solving the problems encountered (many).

To get hardware acceleration you need to start kodi (which is built to be used with GBM as a standalone application) with an user in the ~video~ group (UDEV rules are provided in a Nix module in this flake) and you must enable "DRM PRIME acceleration" and set the "render method" to "direct to plane" in the player settings of kodi. This way I've been able to play 4k h264 and h265/hvec videos, only following two problems are noticed:

• Cannot play videos with HDR (no crash but video is black)
• When UI elements appear during playback (for instance when you pause a movie) the video gets black. As soon as they disappear video reappears. The playback is not stopped, audio doesn't stop, only the video is altered. Not the end of the world but a bit annoying.