d4delta / nix-odroid-n2

Nixos sd image and mainline uboot for Odroid N2

Suitable for a server. Make sure you have your UART.

Kernel patches sourced from the Armbian build.

Built regularily on the nix release-20.03 branch on arm64 hardware.

What's working

• RTC
• Boots from SD, USB, eMMC (tested)
• ethaddr

What's not working

• Resetting the network adapter (ip link set eth0 down/up) requires a reboot!
• WOL
• Linux desktop acceleration (needs panfrost drivers?) (won't fix)

Not tried

• Audio

How to prepare a bootable drive.

Running nix-build links products under the ./result folder. You will need to build an image and uboot and write them to a drive to boot.

1. Build an image (on an aarch64 or x86_64 box)

nix-build release.nix -A sdImage

Then dd it to an sd card (or usb or eMMC)

DEV=/dev/mmcblkX
IMG=./result/???/sd-image-odroid-n2.img
dd if=$IMG of=$DEV conv=fsync bs=4M
sync

2. Build a u-boot (x86_64 box only :S)

Build the firmware package fip that packs u-boot ready for use.

nix-build release.nix -A fip

Then dd it to the sd card (or usb or eMMC)

DEV=/dev/mmcblkX
UBOOT=result/u-boot.bin
dd if=$UBOOT of=$DEV conv=fsync,notrunc bs=512 seek=1
sync

On your first boot

Upon first boot, you will need to setup a /etc/nixos/configuration.nix. Generate one using nixos-generate-config.

Afterwards, refer to the same profile.nix that the sd image was built from. This profile contains the board specific kernel package and configuration.

{ config, pkgs, lib, ... }:

{
  imports = [
    /etc/nixos/hardware-configuration.nix
    /etc/nixos/nix-odroid-n2/modules/profile.nix
  ];
}

Lessons learnt

• When a cross-compiled image is used. NixOS will be rebuilt on the device natively when doing nixos-rebuild.

• Cross-compiling is a means to get something going if you don't have any suitable arm64 hardware. Use arm64 hardware when you can.

• When cross-compiling turn off everything you can till you get something that boots. For example, turn off sound, wifi or filesystem drivers.

• You can build an image on arm64 hardware using nix on Armbian. Ensure you enable enough swap space ~15GB and have a 4GB model. This build will be much quicker because you can leverage the arm64 binary cache.

• Cross-compiling is possible and has been done time to time. It bootstrapped this project. However it is not maintained as arm64 builds work better. YMMV.

References for guidance and patches

• Armbian
• LibreElec
• Hardkernel forums