{
  system,
  nixpkgs,
  default,
  c,
  arch,
  fpu ? null,
}:
with builtins;
with nixpkgs.lib; let
  pkgs = import nixpkgs.outPath {
    localSystem = system;
    crossSystem = {
      config =
        if (hasPrefix "armv" arch)
        then "arm-none-eabi" + (optionalString (fpu != null) "hf")
        else "riscv32-none-elf";
      libc = "newlib-nano";
      gcc =
        {
          inherit arch;
        }
        // (optionalAttrs (fpu != null) {inherit fpu;});
    };
  };
in
  pkgs.buildPackages.mkShell {
    packages = with pkgs.buildPackages;
      [
        kconfig-frontends
        genromfs
        xxd
        openocd
        gcc
        gdb
      ]
      ++ (optionals (hasPrefix "rv32" arch) [
        esptool
      ]);
    inputsFrom = [default c];
    meta.platforms = nixpkgs.lib.platforms.linux;
  }