centos7 kernel 升级内核

rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
#rpm -Uvh http://www.elrepo.org/elrepo-release-7.0-2.el7.elrepo.noarch.rpm
rpm -Uvh https://www.elrepo.org/elrepo-release-7.el7.elrepo.noarch.rpm
yum --disablerepo="*" --enablerepo="elrepo-kernel" list available
#yum --enablerepo=elrepo-kernel install kernel-lt

#离线下载
yum --enablerepo=elrepo-kernel install  kernel-lt kernel-lt-devel kernel-lt-headers  --downloadonly   --downloaddir=./kernel/
cd ./kernel/
yum localinstall kernel-lt*.rpm -y

#查看是否另类引导
cd /boot/grub2/
ls -la grubenv

#查看可用内核列表
awk -F\' '$1=="menuentry " {print i++ " : " $2}' /etc/grub2.cfg
#查看当前默认内核启动项
grub2-editenv list
#更改默认启动内核项，数字就是查看内核列表里对应内核编号
grub2-set-default 0
#重新生成 grub2.cfg
grub2-mkconfig -o /boot/grub2/grub.cfg
#重启系统
reboot