sdimage.nix

{ config, pkgs, ... }:
let
  configTxt = pkgs.writeText "config.txt" ''
    [pi3]
    kernel=u-boot-rpi3.bin
    [pi4]
    kernel=u-boot-rpi4.bin
    enable_gic=1
    armstub=armstub8-gic.bin
    # Otherwise the resolution will be weird in most cases, compared to
    # what the pi3 firmware does by default.
    disable_overscan=1
    [all]
    # Boot in 64-bit mode.
    arm_64bit=1
    # U-Boot needs this to work, regardless of whether UART is actually used or not.
    # Look in arch/arm/mach-bcm283x/Kconfig in the U-Boot tree to see if this is still
    # a requirement in the future.
    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
{
  sdImage = {
    compressImage = false;
    populateFirmwareCommands = ''
      (cd ${pkgs.raspberrypifw}/share/raspberrypi/boot && cp bootcode.bin fixup*.dat start*.elf $NIX_BUILD_TOP/firmware/)
      # Add the config
      cp ${configTxt} firmware/config.txt
      # Add pi3 specific files
      cp ${pkgs.ubootRaspberryPi3_64bit}/u-boot.bin firmware/u-boot-rpi3.bin
      # Add pi4 specific files
      cp ${pkgs.ubootRaspberryPi4_64bit}/u-boot.bin firmware/u-boot-rpi4.bin
      cp ${pkgs.raspberrypi-armstubs}/armstub8-gic.bin firmware/armstub8-gic.bin
      cp ${pkgs.raspberrypifw}/share/raspberrypi/boot/bcm2711-rpi-4-b.dtb firmware/
    '';
    populateRootCommands = ''
      mkdir -p ./files/boot
      ${config.boot.loader.generic-extlinux-compatible.populateCmd} -c ${config.system.build.toplevel} -d ./files/boot
    '';
  };
}