void OSThread::pd_initialize() {

  {- -------------------------------------------
  (1) フィールドの初期化
      ---------------------------------------- -}

      _thread_id                         = 0;
      sigemptyset(&_caller_sigmask);

      _current_callback                  = NULL;
      _current_callback_lock = VM_Version::supports_compare_and_exchange() ? NULL
                        : new Mutex(Mutex::suspend_resume, "Callback_lock", true);

      _saved_interrupt_thread_state      = _thread_new;
      _vm_created_thread                 = false;
    }