package gen_init_cpio, tool for making an initramfs

pkgs/default.nix

@@ -22,6 +22,8 @@
   netlink-lua = callPackage ./netlink-lua {};
   ifwait = callPackage ./ifwait {};
 
+  gen_init_cpio = callPackage ./gen_init_cpio {};
+
   serviceFns = callPackage ./service-fns {};
 
   # these are packages for the build system not the host/target

pkgs/gen_init_cpio/default.nix

@@ -0,0 +1,17 @@
+{
+  stdenv
+, fetchurl
+}:
+stdenv.mkDerivation rec {
+  name = "gen_init_cpio";
+  src = fetchurl {
+    url = "https://raw.githubusercontent.com/torvalds/linux/462cd7724e2341472c9f9670ac88e250788d4c82/usr/gen_init_cpio.c";
+    hash = "sha256-gwKSJGiCS4v98EArNryr/sdYAfDqnGsZ1erfGMNVjpw=";
+  };
+  unpackPhase = "cp ${src} ./gen_init_cpio.c";
+  buildPhase = "gcc -o gen_init_cpio gen_init_cpio.c";
+  installPhase = ''
+    mkdir -p $out/bin
+    cp gen_init_cpio $out/bin
+  '';
+}