{
  inputs = {
    fenix-flake = {
      url = "github:nix-community/fenix";
      inputs.nixpkgs.follows = "nixpkgs";
    };
  };
  outputs = { self, fenix-flake, flake-utils, nixpkgs }:
    flake-utils.lib.eachSystem [ "aarch64-linux" "x86_64-linux" ] (system:
      let
        pkgsBuild = nixpkgs.legacyPackages.${system};
        pkgsHost = import nixpkgs {
          inherit system;
          crossSystem.config = "riscv64-unknown-none-elf";
        };
        fenix = fenix-flake.packages.${system};

        toolchain = fenix.combine [
          fenix.stable.cargo
          fenix.stable.rustc
          fenix.stable.clippy
          fenix.targets.riscv64gc-unknown-none-elf.stable.rust-std
        ];
        rust = pkgsHost.makeRustPlatform {
          cargo = toolchain;
          rustc = toolchain;
        };

        packages = rec {
          boards = import ./boards {
            inherit libkernel;
            pkgs = pkgsHost;
          };
          libkernel = pkgsBuild.callPackage ./kernel { inherit rust; };
        };
        run-vm = pkgsBuild.writeShellApplication {
          name = "run-vm";

          runtimeInputs = [ pkgsBuild.qemu ];

          text = ''
            set -x
            qemu-system-riscv64 \
              -machine virt \
              -m 1G \
              -nographic \
              -bios none \
              -kernel ${packages.boards.qemu-virt}/kernel.elf \
              "$@"
          '';
        };
      in {
        apps = {
          default = {
            type = "app";
            program = pkgsBuild.lib.getExe run-vm;
          };

          debug = {
            type = "app";
            program = pkgsBuild.lib.getExe (pkgsBuild.writeShellApplication {
              name = "run-vm-debug";
              runtimeInputs = [ run-vm ];
              text = ''
                port=$(( 1000 * ("$(id -u)" - 990) ))
                run-vm -gdb tcp::$port -S "$@"
              '';
            });
          };

          gdb = {
            type = "app";
            program = pkgsBuild.lib.getExe (pkgsBuild.writeShellApplication {
              name = "gdb";
              runtimeInputs = [ toolchain ];
              text = ''
                port=$(( 1000 * ("$(id -u)" - 990) ))
                rust-gdb ${packages.boards.qemu-virt}/kernel.elf \
                  -ex "target remote 127.0.0.1:$port" \
                  -ex "set riscv use-compressed-breakpoints yes" \
                  -ex "layout src" \
                  -ex "focus cmd" \
                  -ex "tbreak hart0_boot" \
                  -ex "c"
              '';
            });
          };
        };

        devShells.default = pkgsBuild.mkShell {
          inputsFrom =
            builtins.attrValues (flake-utils.lib.flattenTree packages);
          nativeBuildInputs = [
            pkgsBuild.cargo-watch
            pkgsBuild.qemu
            pkgsHost.stdenv.cc.bintools.bintools
          ];
          CARGO_BUILD_TARGET = "riscv64gc-unknown-none-elf";
        };

        packages = flake-utils.lib.flattenTree packages;
      });
}