在4.1实时内核起来之后内核打印出如下信息：
[ 19.511620] cpu cpu0: cpu0 clock notifier not ready, retry
[ 19.534974] cpu cpu0: of_pm_voltdm_notifier_register: Failed to get cpu0 regulator/voltdm: -517
[ 19.562491] cpu cpu0: cpu0 clock notifier not ready, retry
这个是什么意思，怎么解决呢？