librt {
  GLIBC_2.1 {
    # AIO functions.
    aio_cancel; aio_cancel64; aio_error; aio_error64; aio_fsync; aio_fsync64;
    aio_init; aio_read; aio_read64; aio_return; aio_return64; aio_suspend;
    aio_suspend64; aio_write; aio_write64; lio_listio; lio_listio64;
  }
  GLIBC_2.2 {
    # c*
    clock_getres; clock_gettime; clock_settime; clock_getcpuclockid;
    clock_nanosleep;

    # s*
    shm_open; shm_unlink;

    # t*
    timer_create; timer_delete; timer_getoverrun; timer_gettime;
    timer_settime;
  }
}