nixpkgs/test/make-initrd.nix

# Create an initial ramdisk containing the closure of the specified
# `init' package.  An initial ramdisk is used during the initial
# stages of booting a Linux system.  It is loaded by the boot loader
# along with the kernel image.  It's supposed to contain everything
# (such as kernel modules) necessary to allow us to mount the root
# file system.  Once the root file system is mounted, the `real' boot
# script can be called.
#
# An initrd is really just a gzipped cpio archive.
#
# A symlink `/init' is made to the store path passed in the `init'
# argument.

{stdenv, cpio, init}:

stdenv.mkDerivation {
  name = "initrd";
  builder = ./make-initrd.sh;
  buildInputs = [cpio];
  inherit init;
  
  # For obtaining the closure of `init'.
  exportReferencesGraph = ["init-closure" init];
  pathsFromGraph = ./paths-from-graph.sh;
}