There's unused and untested large pages code in os_bsd.cpp, which was copied over from os_linux.cpp. It's not used because large pages is not supported on BSD. See arguments.cpp:
#ifdef _ALLBSD_SOURCE // UseLargePages is not yet supported on BSD.
  UNSUPPORTED_OPTION(UseLargePages, "-XX:+UseLargePages");
#endif

Since this code is not used or tested we should probably remove it.