nixos-iot-node/workspace/rpi2.nix

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

{
  imports = [ <nixpkgs/nixos/modules/installer/sd-card/sd-image.nix> ];

  # Define the image name
  sdImage.imageBaseName = "nixos-rpi2";
  sdImage.compressImage = false;

  # Required: Set populateRootCommands
  sdImage.populateRootCommands = ''
    mkdir -p ./files
    echo "NixOS for Raspberry Pi 2" > ./files/welcome.txt
  '';
  sdImage.populateFirmwareCommands = "";

  # Bootloader: Use U-Boot for Raspberry Pi 2
  boot.loader.generic-extlinux-compatible.enable = true;
  hardware.deviceTree.enable = true;
  hardware.deviceTree.name = "bcm2836-rpi-2-b.dtb"; # Correct DTB for RPi2

  # Disable GRUB (not used on Raspberry Pi)
  boot.loader.grub.enable = false;

  # Networking
  networking.hostName = "nixos-rpi2";
  networking.wireless.enable = false; # Enable this if using WiFi
  networking.interfaces.eth0.useDHCP = true;

  # Enable SSH
  services.openssh.enable = true;

  # User setup
  users.users.nixos = {
    isNormalUser = true;
    initialPassword = "nixos";
    extraGroups = [ "wheel" ];
  };
  users.groups.nixos = {};
  
  # Set system version (avoid warnings)
  system.stateVersion = "25.05";

  # Enable cross-compilation
  nixpkgs.crossSystem = {
    system = "armv7l-linux";
  };
}