libc {
  GLIBC_2.4 {
    ioperm; iopl;
    inb; inw; inl;
    outb; outw; outl;
  }
  GLIBC_2.11 {
    fallocate64;
  }
  GLIBC_2.24 {
    recvmsg; sendmsg;
  }
  GLIBC_PRIVATE {
    # A copy of sigaction lives in libpthread, and needs these.
    __default_sa_restorer; __default_rt_sa_restorer;
    # nptl/pthread_cond_timedwait.c uses INTERNAL_VSYSCALL(clock_gettime).
    __vdso_clock_gettime;
  }
}