anchor.diff: -{ lib, stdenv, fetchurl, liburcu, python3 }:
  +{ lib, stdenv, fetchurl, pkg-config, liburcu, numactl, python3 }:
   
   # NOTE:
   #   ./configure ...
  
positive.code: 
    propagatedBuildInputs = [ liburcu ];
  
    meta = with lib; {
      description = "LTTng Userspace Tracer libraries";
      homepage = "https://lttng.org/";
      license = licenses.lgpl21Plus;
      platforms = platforms.linux;
      maintainers = [ maintainers.bjornfor ];
    };
  
negative.code: 
  stdenv.mkDerivation rec {
    pname = "lttng-ust";
    version = "2.13.0";
  
    src = fetchurl {
      url = "https://lttng.org/files/lttng-ust/${pname}-${version}.tar.bz2";
      sha256 = "0l0p6y2zrd9hgd015dhafjmpcj7waz762n6wf5ws1xlwcwrwkr2l";
    };
  
    nativeBuildInputs = [ pkg-config ];
    buildInputs = [ numactl python3 ];
  
    preConfigure = ''
      patchShebangs .
  