+++
title = "Running NixOS on a NanoPi R5S"
date = 2023-07-30T08:51:46Z
[taxonomies]
tags = ["NixOS", "home-networking", "infrastructure"]
+++

I managed to get [NixOS](https://nixos.org) running on my [NanoPi R5S](https://www.friendlyelec.com/index.php?route=product/product&product_id=287) ([FriendlyElec Wiki](https://wiki.friendlyelec.com/wiki/index.php/NanoPi_R5S)).

Firstly, I flashed a pre-built stock Debian image from [inindev](https://github.com/inindev/nanopi-r5) to an SD card. This can be used as a rescue system later on. 

From that SD card, I then flashed the same system onto the internal <abbr title="embedded MultiMediaCard">eMMC</abbr> Storage. I only really needed to this to ensure UBoot was correctly installed; I think there will be an easier way to do it.

I had nix already installed on the <abbr title="Non-Volatile Memory Express">NVMe</abbr> <abbr title="Solid-State Drive">SSD</abbr> along with a home directory. I bind-mounted `/nix` and `/home` following the fstab I had previously set up:

```conf
UUID=replaceme  /mnt    ext4    relatime,lazytime   0 2
/mnt/nix        /nix    none    defaults,bind       0 0
/mnt/srv        /srv    none    defaults,bind       0 0
/mnt/home       /home   none    defaults,bind       0 0
```

I then created a user for myself using that home directory, I had full access to nix in the new Debian environment. This meant I had access to `nixos-install`. 

I wanted to use the [extlinux support in UBoot](https://u-boot.readthedocs.io/en/latest/develop/distro.html#boot-configuration-files), so I made `/mnt/boot` point to `/boot` on the <abbr>eMMC</abbr>:

```sh
mkdir /mnt/{emmc,boot}
mount LABEL=rootfs /mnt/emmc
mount --bind /mnt/emmc /mnt/boot
```

<aside>
One could <em>probably</em> delete everything else on the <abbr>eMMC</abbr> and move the contents of <code>/mnt/emmc/boot</code> to <code>/mnt/emmc</code>, thus obviating the need to bind-mount <code>/boot</code>
</aside>

I ran `nixos-generate-config` as usual, which set up the mount points in `hardware-configuration.nix` correctly. `configuration.nix` needed a bit of tweaking. My first booting configuration was something like this, mostly borrowed from [Artem Boldariev's comment](https://github.com/inindev/nanopi-r5/issues/11#issue-1789308883):

```nix
{ config
, pkgs
, lib
, ...
}:
let
  fsTypes = [ "f2fs" "ext" "exfat" "vfat" ];
in
{
  imports = [ ./hardware-configuration.nix ];
  boot = {
    kernelParams = [ "console=tty0" ];
    # partial Rockchip related changes from Debian 12 kernel version 6.1
    # Also, see here:
    # https://discourse.nixos.org/t/how-to-provide-missing-headers-to-a-kernel-build/11422/3
    kernelPatches = [
      {
        name = "rockchip-config.patch";
        patch = null;
        extraConfig = ''
          PHY_ROCKCHIP_PCIE Y
          PCIE_ROCKCHIP_EP y
          PCIE_ROCKCHIP_DW_HOST y
          ROCKCHIP_VOP2 y
        '';
      }
      {
        name = "status-leds.patch";
        patch = null;
        # old:
        # LEDS_TRIGGER_NETDEV y
        extraConfig = ''
          LED_TRIGGER_PHY y
          USB_LED_TRIG y
          LEDS_BRIGHTNESS_HW_CHANGED y
          LEDS_TRIGGER_MTD y
        '';
      }
    ];
    
    supportedFilesystems = fsTypes;
    initrd.supportedFilesystems = fsTypes;

    initrd.availableKernelModules = [
      ## Rockchip
      ## Storage
      "sdhci_of_dwcmshc"
      "dw_mmc_rockchip"

      "analogix_dp"
      "io-domain"
      "rockchip_saradc"
      "rockchip_thermal"
      "rockchipdrm"
      "rockchip-rga"
      "pcie_rockchip_host"
      "phy-rockchip-pcie"
      "phy_rockchip_snps_pcie3"
      "phy_rockchip_naneng_combphy"
      "phy_rockchip_inno_usb2"
      "dwmac_rk"
      "dw_wdt"
      "dw_hdmi"
      "dw_hdmi_cec"
      "dw_hdmi_i2s_audio"
      "dw_mipi_dsi"
    ];
    loader = {
      timeout = 3;
      grub.enable = false;
      generic-extlinux-compatible = {
        enable = true;
        useGenerationDeviceTree = true;
      };
    };
  };
  # Most Rockchip CPUs (especially with hybrid cores) work best with "schedutil"
  powerManagement.cpuFreqGovernor = "schedutil";
  
  boot.kernelParams = [
    "console=tty1"
    "console=ttyS2,1500000"
    "earlycon=uart8250,mmio32,0xfe660000"
  ];
  # Let's blacklist the Rockchips RTC module so that the
  # battery-powered HYM8563 (rtc_hym8563 kernel module) will be used
  # by default
  boot.blacklistedKernelModules = [ "rtc_rk808" ];

  # ... typical config omitted for brevity
}
```

Due to the custom kernel configuration, building takes a while. I set up a [distributed build](https://nixos.org/manual/nix/stable/advanced-topics/distributed-builds.html) to speed things up, using a [Hetzner Cloud](https://www.hetzner.com/cloud) CAX21 ARM64 instance (although I could have used an x86_64 system with one of the methods mentioned on the [NixOS on ARM NixOS wiki page](https://nixos.wiki/wiki/NixOS_on_ARM#Build_your_own_image_natively)). This made for a very long `nixos-install` command line:

```sh
sudo env PATH=$PATH =nixos-install --root /mnt --no-channel-copy --channel https://nixos.org/channels/nixos-23.05 --option builders'ssh://my-host aarch64-linux /root/.ssh/id_pappel_nixpkgs 4 2 big-parallel' --option builders-use-substitutes true --max-jobs 0
```

I added `setenv bootmeths "extlinux"` to `/boot/boot.txt` and ran `/boot/mkscr.sh` as root to ensure that UBoot would search for the `extlinux.conf` file