# Base image for building SD images for my Pi 3's
#
# To build, use:
# imports = [ ./sd-image_paidh-base ]
{
  config,
  lib,
  pkgs,
  ...
}: let
  extlinux-conf-builder = import
  <nixpkgs/nixos/modules/system/boot/loader/generic-extlinux-compatible/extlinux-conf-builder.nix> {
    pkgs = pkgs.buildPackages;
  };
in {
  imports = [
    <nixpkgs/nixos/modules/profiles/base.nix>
    <nixpkgs/nixos/modules/installer/sd-card/sd-image.nix>
  ];

  boot.consoleLogLevel = lib.mkDefault 7;

  sdImage = {
    populateFirmwareCommands = let
      configTxt = pkgs.writeText "config.txt" ''
        kernel=u-boot-rpi3.bin

        # Boot in 64-bit mode.
        arm_control=0x200

        # U-Boot used to need this to work, regardless of whether UART is actually used or not.
        # TODO: check when/if this can be removed.
        enable_uart=1

        # Prevent the firmware from smashing the framebuffer setup done by the mainline kernel
        # when attempting to show low-voltage or overtemperature warnings.
        avoid_warnings=1
      '';
    in ''
      (cd ${pkgs.raspberrypifw}/share/raspberrypi/boot && cp bootcode.bin fixup*.dat start*.elf $NIX_BUILD_TOP/firmware/)
      cp ${pkgs.ubootRaspberryPi3_64bit}/u-boot.bin firmware/u-boot-rpi3.bin
      cp ${configTxt} firmware/config.txt
    '';
    populateRootCommands = ''
      mkdir -p ./files/boot
      ${extlinux-conf-builder} -t 3 -c ${config.system.build.toplevel} -d ./files/boot
    '';
  };
}