nixpkgs/pkgs/os-specific/linux/microcode/amd.nix

{ lib, stdenv, linux-firmware, libarchive }:

stdenv.mkDerivation {
  pname = "amd-ucode";
  version = linux-firmware.version;

  src = linux-firmware;

  sourceRoot = ".";

  nativeBuildInputs = [ libarchive ];

  buildPhase = ''
    mkdir -p kernel/x86/microcode
    find ${linux-firmware}/lib/firmware/amd-ucode -name \*.bin -print0 | sort -z |\
      xargs -0 -I{} sh -c 'cat {} >> kernel/x86/microcode/AuthenticAMD.bin'
  '';

  installPhase = ''
    mkdir -p $out
    touch -d @$SOURCE_DATE_EPOCH kernel/x86/microcode/AuthenticAMD.bin
    echo kernel/x86/microcode/AuthenticAMD.bin | bsdtar --uid 0 --gid 0 -cnf - -T - | bsdtar --null -cf - --format=newc @- > $out/amd-ucode.img
  '';

  meta = with lib; {
    description = "AMD Processor microcode patch";
    homepage = "https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git";
    license = licenses.unfreeRedistributableFirmware;
    platforms = platforms.linux;
  };
}