nix-files/cfg/hardware.nix

# this file originates from ‘nixos-generate-config’
# but has been heavily modified
{ config, lib, pkgs, modulesPath, ... }:

{
  # enables non-free firmware
  hardware.enableRedistributableFirmware = true;

  # XXX colin: these four statements were autogenerated and placed here: why?
  # boot.initrd.availableKernelModules = [ "xhci_pci" "usbhid" "usb_storage" ];
  # boot.initrd.kernelModules = [ ];
  # boot.kernelModules = [ ];
  # boot.extraModulePackages = [ ];

  # default nixos-21.11 kernel of 5.10 doesn't have the rpi-400 device tree blob.
  # turns out 5.15, 5.16, 5.17 are all unable to boot the pi from usb (they fail to "direct load" certain broadcom firmware).
  # linuxPackages_rpi4 uses 5.10, but supplies the pi-400 dtb & boots fine.
  # boot.kernelPackages = pkgs.linuxPackages_latest;
  # boot.kernelPackages = pkgs.linuxPackages_5_15;
  # boot.kernelPackages = pkgs.linuxPackages_5_16;
  boot.kernelPackages = pkgs.linuxPackages_rpi4;

  # NixOS defaults to grub: we don't want that.
  boot.loader.grub.enable = false;
  # raspberryPi boot loader creates extlinux.conf.
  #   otherwise, enable the generic-extlinux-compatible loader below.
  # note: THESE ARE MUTUALLY EXCLUSIVE. generic-extlinux-compatible causes uboot to not be built
  # boot.loader.generic-extlinux-compatible.enable = true;
  boot.loader.raspberryPiColin.enable = true;
  boot.loader.raspberryPiColin.uboot.enable = true;
  boot.loader.raspberryPiColin.version = 4;

  boot.initrd.availableKernelModules = [
    "bcm2711_thermal"
    "bcm_phy_lib"
    "brcmfmac"
    "brcmutil"
    "broadcom"
    "clk_raspberrypi"
    "drm"  # Direct Render Manager
    "enclosure"  # SCSI ?
    "fuse"
    "mdio_bcm_unimac"
    "pcie_brcmstb"
    "raspberrypi_cpufreq"
    "raspberrypi_hwmon"
    "ses"  # SCSI Enclosure Services
    "uas"  # USB attached storage
    "uio"  # userspace IO
    "uio_pdrv_genirq"
    "xhci_pci"
    "xhci_pci_renesas"
  ];
  # boot.initrd.compressor = "gzip";  # defaults to zstd
  # hack in the `boot.shell_on_fail` arg since it doesn't seem to work otherwise
  boot.initrd.preFailCommands = "allowShell=1";
  # default: 4 (warn). 7 is debug
  boot.consoleLogLevel = 7;
  # boot.kernelParams = [
  #   "boot.shell_on_fail"
  #   # "boot.trace"
  #   # "systemd.log_level=debug"
  #   # "systemd.log_target=console"
  # ];

  # ondemand power scaling keeps the cpu at low frequency when idle, and sets to max frequency
  # when load is detected. (v.s. the "performance" default, which always uses the max frequency)
  powerManagement.cpuFreqGovernor = "ondemand";
}