nixos-omnia

🚧 Work in progress 🚧

Overlay and sample configuration.nix which can be used to build an installer image or medkit tarball for Turris Omnia router.

For support check out #nixos-on-your-router@freenode.

Upgrading u-boot

For painless set-up, we need UBoot with CONFIG_DISTRO_DEFAULTS which was enabled only recently. Updated version is availabe and buildable on NixOS at https://gitlab.nic.cz/turris/turris-omnia-uboot/ in omnia-2019 branch.

Build

To build u-boot-spl.kwb use

nix-build -o result-uboot \
  -E '(import <nixpkgs> { overlays = [ (import ./overlay.nix) ]; crossSystem = "armv7l-linux"; } ).uBootOmnia'

Also if for some reason you've managed to break your UBoot, ./result-uboot contains kwboot executable which can load UBoot over UART.

Prepare TFTP server

Following NixOS configuration snippet can be used to quickly set-up private LAN using e.g. USB ethernet dongle. You can use any free interface

• make sure to replace enp8s0u2 with your "external" interface name.

let
  extIf = "enp8s0u2";
in
{

  networking.interfaces."${extIf}" = {
    ipv4.addresses = [
      { address = "192.168.142.1"; prefixLength = 24; }
    ];
  };

  networking.firewall.allowedUDPPorts = [
    68 69 # tftp
  ];

  services.dhcpd4 = {
     enable = true;
     interfaces = [ extIf ];
     extraConfig = ''
       option routers 192.168.42.1;
       option broadcast-address 192.168.142.255;
       option subnet-mask 255.255.255.0;
       option domain-name-servers 1.1.1.1;
       subnet 192.168.142.0 netmask 255.255.255.0 {
         range 192.168.142.100 192.168.142.200;
       }
    '';
  };

  services.tftpd = {
    enable = true;
    path = "/srv/tftp";
  };
}

Save the snippet as file and import it from your configuration.nix. After switching copy UBoot from previous step to TFTP root dir:

mkdir -p /srv/tftp
cp ./result-uboot/u-boot-spl.kwb /srv/tftp/u-boot-spl.kwb

Load and flash to SPI

Connect your external interface to WAN port on the Omnia, reset, break boot when prompted and issue following commands:

dhcp
setenv serverip 192.168.142.1
tftpboot ${kernel_addr_r} u-boot-spl.kwb

sf probe
sf update ${kernel_addr_r} 0 ${filesize}

Building medkit tarball

To build either natively or using cross compilation toolchain, use

./build-medkit.sh

Loading

Format flash drive, it absolutely needs to have at least one partition on it.

mkfs.btrfs /dev/sdXY
mount /dev/sdXY /mnt
cp ./result-medkit/*.tar.gz /mnt/
umount /mnt

Plug into Omnia, hold reset for 4 seconds (4 leds on) which starts recovery mode which then copies contents of medkit tarball to MMC.

UBoot shell

After medkit does its job, break into UBoot shell and issue

sysboot mmc 0:1 any ${scriptaddr} /@/boot/extlinux/extlinux.conf

to boot from NixOS installed on MMC.

To make this permanent, use

setenv bootmcd sysboot mmc 0:1 any ${scriptaddr} /@/boot/extlinux/extlinux.conf
saveenv

Now you're pretty much done with bootstrapping. Set-up SSH keys or root password and deploy new configuration remotely.

Building the installer SD image

🚧 Warning 🚧

While the installer SD image boots automatically, you probably cannot use it to install NixOS using nixos-install. While nixos-generate-config works correctly, there are no armv7l binary cache ~~and the device might not have enough memory to perform evaluation and installation~~. There are couple of hardware variants, some have 2GB memory.

Installer image can still be useful for remote bootstrapping using x86 or armv7l machine.

Build

To build either natively or using cross compilation toolchain, use

./build-sdimage.sh

Flashing the installer

dd if=result-img/sd-image/nixos-omnia-sd-image-20.09pre-git-armv7l-linux.img \
   of=/dev/sdXY \
   bs=1M

Installation

Proceed according to standard NixOS installation instructions.

In configuration.nix, make sure you enable at least

boot.initrd.supportedFilesystems = [ "btrfs" ];

If using cross-compiled installer the initial installation might take several days as Nix cannot reuse cross-compiled packages from installers /nix/store and has to build whole world from scratch including bootstrap packages. Make sure to supply additional cooling or limit the compilation to 3 cores with --option cores 3.