rpmbuild kernel rngd 漫长等待解决

自己编译CentOS 内核时候，通过 src rpm 包定制，rpmbuild 的时候，发现一直 hold 在
那里不动：


### Now generating a PGP key pair to be used for signing modules.
###
### If this takes a long time, you might wish to run rngd in the background to
### keep the supply of entropy topped up.  It needs to be run as root, and
### should use a hardware random number generator if one is available, eg:
###
###     rngd -r /dev/hwrandom
###
### If one isn't available, the pseudo-random number generator can be used:
###
###     rngd -r /dev/urandom


看上面的提示，解决办法：

yum install rng-tools

再开一个终端，root 用户执行：

rngd -r /dev/urandom