anchor.diff:  
   stdenv.mkDerivation rec {
     pname = "ipxe";
  -  version = "1.21.1";
  +  version = "unstable-2022-04-06";
   
  -  nativeBuildInputs = [ perl cdrkit xz openssl gnu-efi mtools ] ++ lib.optional stdenv.hostPlatform.isx86 syslinux;
  +  nativeBuildInputs = [ gnu-efi mtools openssl perl xorriso xz ] ++ lib.optional stdenv.hostPlatform.isx86 syslinux;
   
     src = fetchFromGitHub {
       owner = "ipxe";
       repo = "ipxe";
  -    rev = "v${version}";
  -    sha256 = "1pkf1n1c0rdlzfls8fvjvi1sd9xjd9ijqlyz3wigr70ijcv6x8i9";
  +    rev = "70995397e5bdfd3431e12971aa40630c7014785f";
  +    sha256 = "SrTNEYk13JXAcJuogm9fZ7CrzJIDRc0aziGdjRNv96I=";
     };
   
     # not possible due to assembler code
  
positive.code: 
    enableParallelBuilding = true;
  
    meta = with lib;
      { description = "Network boot firmware";
        homepage = "https://ipxe.org/";
  
negative.code: 
    makeFlags =
      [ "ECHO_E_BIN_ECHO=echo" "ECHO_E_BIN_ECHO_E=echo" # No /bin/echo here.
      ] ++ lib.optional (embedScript != null) "EMBED=${embedScript}";
  
  
  