message: Show errno.
diff: @@ -321,7 +321,7 @@ static void swKqueueSignal_set(int signo, swSignalHandler handler)
  {
  int fd;
  } *reactor_obj = reactor->object;
  - int new_event_num;
  + uint32_t new_event_num;
  // clear signal
  if (handler == NULL)
  {
  @@ -355,7 +355,7 @@ static void swKqueueSignal_set(int signo, swSignalHandler handler)
  {
  if (unlikely(handler))
  {
  - swWarn("kevent set signal[%d] error", signo);
  + swWarn("kevent set signal[%d] error, errno=%d", signo, errno);
  }
  return;
  }
  