anchor.diff:  
       # cam integration
       libevent
  +    libdrm
  +
  +    # hotplugging
  +    systemd
   
       # lttng tracing
       lttng-ust
  
positive.code: , doxygen
  , python3
  , python3Packages
  }:
  
  stdenv.mkDerivation {
    pname = "libcamera";
    version = "unstable-2021-09-24";
  
    src = fetchgit {
      url = "https://git.libcamera.org/libcamera/libcamera.git";
      rev = "40f5fddca7f774944a53f58eeaebc4db79c373d8";
      sha256 = "0jklgdv5ma4nszxibms5lkf5d2ips7ncynwa1flglrhl5bl4wkzz";
    };
  
    postPatch = ''
  
negative.code:     openssl
    ];
  
    mesonFlags = [
      "-Dv4l2=true"
      "-Dqcam=disabled"
      "-Dlc-compliance=disabled" # tries unconditionally to download gtest when enabled
      ];
  
    # Fixes error on a deprecated declaration
    NIX_CFLAGS_COMPILE = "-Wno-error=deprecated-declarations";
  
    # Silence fontconfig warnings about missing config
    FONTCONFIG_FILE = makeFontsConf { fontDirectories = []; };
  
    meta = with lib; {
      description = "An open source camera stack and framework for Linux, Android, and ChromeOS";
  