# SD-card image of this host, used exactly once: to bring the board up.
#
# Deliberately NOT imported by ./configuration.nix. The flake extends the host
# with it (see packages.aarch64-linux.zero2w-sd-image in ../../flake.nix), so
# the card carries the host's own kernel, config.txt and SSH keys rather than a
# generic installer that then has to be reconfigured over a console this host
# does not have -- pppd owns the serial port (./serial-ppp.nix).
#
# It does not carry the runtime secrets. Seed those into the card's root
# partition before first boot; see ../../docs/hosts/pizero2w.md.
{
  config,
  lib,
  modulesPath,
  ...
}:
{
  imports = [ "${modulesPath}/installer/sd-card/sd-image.nix" ];

  # sd-image.nix pulls in profiles/all-hardware.nix, which is every driver and
  # firmware blob NixOS knows about. The raspberry-pi-3 profile already carries
  # what this board has, and the card is small.
  hardware.enableAllHardware = lib.mkForce false;

  image.baseName = "nixos-zero2w";

  sdImage = {
    # Compressing costs a long single-threaded pass and buys nothing: the image
    # is written straight to a card with dd.
    compressImage = false;

    # The default 30 MiB does not hold the vendor GPU firmware, U-Boot and the
    # BCM2837 device trees and overlays that nixos-hardware installs here.
    firmwareSize = 128;

    # The firmware partition is populated by nixos-hardware's firmware module
    # (it takes over sdImage.populateFirmwareCommands); the root side is the
    # stock extlinux install, which no longer arrives with it.
    populateRootCommands = ''
      mkdir -p ./files/boot
      ${config.boot.loader.generic-extlinux-compatible.populateCmd} -c ${config.system.build.toplevel} -d ./files/boot
    '';
  };
}