查看当前
uname -r
1.导入key
rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
2.安装elrepo的yum源
rpm -Uvh http://www.elrepo.org/elrepo-release-7.0-2.el7.elrepo.noarch.rpm
3.安装内核
yum --enablerepo=elrepo-kernel install kernel-ml-devel kernel-ml
4.查看默认启动顺序
awk -F\‘ ‘$1=="menuentry " {print $2}‘ /etc/grub2.cfg
grub2-set-default 0
删除旧内核
yum remove kernel
原文：http://www.cnblogs.com/dsh942642/p/7190508.html