Hi folks, I’ve been experimenting with building an sd-image for my raspberry pi v1. I’m using the following configuration.nix after some trial and error:
Summary
{
imports = [
<nixpkgs/nixos/modules/profiles/minimal.nix>
<nixpkgs/nixos/modules/installer/sd-card/sd-image.nix>
];
nixpkgs.overlays = [
(self: super: {
# btrfs-progs by default builds with Python bindings. There's a
# long-standing issue where python bindings fail to
# cross-compile because the build system's headers are used
# instead (and I'm building on x86_64 which has long ints of
# 64bits, but armv6l has long ints of 32bits and that causes
# mayhem). Simply disable python bindings. A braver soul would
# find a way to fix Python's build system I guess.
btrfs-progs = super.btrfs-progs.overrideAttrs (old: old // {
configureFlags = [ "--disable-python" ];
installFlags = [];
});
})
# https://github.com/NixOS/nixpkgs/issues/126755#issuecomment-869149243
(self: super: {
makeModulesClosure = x:
super.makeModulesClosure (x // { allowMissing = true; });
})
];
boot.loader.grub.enable = false;
boot.loader.generic-extlinux-compatible.enable = true;
boot.consoleLogLevel = lib.mkDefault 7;
boot.kernelPackages = pkgs.linuxKernel.packages.linux_rpi1;
networking.useDHCP = true;
sdImage = {
populateFirmwareCommands = let
configTxt = pkgs.writeText "config.txt" ''
# 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
[pi0]
kernel=u-boot-rpi0.bin
[pi1]
kernel=u-boot-rpi1.bin
'';
in ''
(cd ${pkgs.raspberrypifw}/share/raspberrypi/boot && cp bootcode.bin fixup*.dat start*.elf $NIX_BUILD_TOP/firmware/)
cp ${pkgs.ubootRaspberryPiZero}/u-boot.bin firmware/u-boot-rpi0.bin
cp ${pkgs.ubootRaspberryPi}/u-boot.bin firmware/u-boot-rpi1.bin
cp ${configTxt} firmware/config.txt
'';
populateRootCommands = ''
mkdir -p ./files/boot
${config.boot.loader.generic-extlinux-compatible.populateCmd} -c ${config.system.build.toplevel} -d ./files/boot
'';
};
nixpkgs.crossSystem.system = "armv6l-linux";
services.openssh.enable = true;
# put your own configuration here, for example ssh keys:
users.extraUsers.root.openssh.authorizedKeys.keys = [
"REDACTED"
];
system.stateVersion = "22.05";
}
Now I’m running into a bit of an issue: the Pi boots just fine, I can ssh to it. I tried running nix-shell -p hello and it failed as the channels were not present, so I ran nix-channel --update. After that, nix-shell -p hello seems to works, but it wants to rebuild the entire universe (a newer linux, clang, etc.). That will take ages on the Pi.
My issue: the sd-image includes no configuration.nix and no channels. Ideally I’d like to build this with the configuration.nix I used to cross-compile, and the channels as they exist on my desktop. At least this would guarantee that I won’t have to rebuild the kernel and clang if I forgot to update channels before building (as long as I don’t update them on the Pi as well). Is there a way to say “cross compile and copy the channels and configuration into the sd-image”?
Thanks,