centos7上运行`rngd -v`命令问题

Question

在centos7上运行rngd -v，出现如下错误信息：

[root@centos7 ~]# rngd -v
Failed to init entropy source 0: Hardware RNG Device

Failed to init entropy source 1: TPM RNG Device

Available entropy sources:
2: Intel RDRAND Instruction RNG

应该怎么办？