feat: add build shell

firmware-build-shell.nix

@@ -0,0 +1,30 @@
+{
+  buildFHSEnv,
+  toolchain,
+  toolchainDir ? "opt/toolchains/crosstools-arm-gcc-4.6-linux-3.4-uclibc-0.9.32-binutils-2.21-NPTL",
+}:
+(buildFHSEnv {
+  name = "firmware-build-env";
+
+  targetPkgs =
+    pkgs:
+    [
+      pkgs.gcc
+
+      # undocumented deps
+      pkgs.libuuid
+      pkgs.lzo
+    ]
+    ++ pkgs.linux.nativeBuildInputs;
+
+  extraOutputsToInstall = [ "dev" ];
+
+  extraBuildCommands = ''
+    mkdir -p ${toolchainDir}
+    ln -s ${toolchain} ${toolchainDir}/usr
+  '';
+
+  profile = ''
+    export PATH=/${toolchainDir}/usr/bin:"$PATH"
+  '';
+}).env

flake.nix

@@ -28,6 +28,18 @@
       );
     in
     {
+      devShells = forAllSystems (
+        system:
+        let
+          pkgs = nixpkgsFor.${system}.native;
+        in
+        {
+          firmware-build = pkgs.callPackage ./firmware-build-shell.nix {
+            toolchain = self.packages.${system}.default;
+          };
+        }
+      );
+
       formatter = forAllSystems (system: nixpkgsFor.${system}.native.nixfmt-rfc-style);
 
       packages = forAllSystems (