anchor.diff:      ++ optionals cephSupport [ ceph ]
       ++ optionals openGLSupport [ mesa epoxy libdrm ]
       ++ optionals virglSupport [ virglrenderer ]
  +    ++ optionals libiscsiSupport [ libiscsi ]
       ++ optionals smbdSupport [ samba ];
   
     enableParallelBuilding = true;
  
positive.code:     ++ optional openGLSupport "--enable-opengl"
      ++ optional virglSupport "--enable-virglrenderer"
      ++ optional tpmSupport "--enable-tpm"
      ++ optional smbdSupport "--smbd=${samba}/bin/smbd";
  
    doCheck = false; # tries to access /dev
  
negative.code: , cephSupport ? false, ceph
  , openGLSupport ? sdlSupport, mesa, epoxy, libdrm
  , virglSupport ? openGLSupport, virglrenderer
  , libiscsiSupport ? true, libiscsi
  , smbdSupport ? false, samba
  , tpmSupport ? true
  , hostCpuOnly ? false
  