centos7.9 更换内核

wget http://mirrors.coreix.net/elrepo-archive-archive/kernel/el7/x86_64/RPMS/kernel-lt-devel-5.4.226-1.el7.elrepo.x86_64.rpm
wget http://mirrors.coreix.net/elrepo-archive-archive/kernel/el7/x86_64/RPMS/kernel-lt-headers-5.4.226-1.el7.elrepo.x86_64.rpm
wget http://mirrors.coreix.net/elrepo-archive-archive/kernel/el7/x86_64/RPMS/kernel-lt-5.4.226-1.el7.elrepo.x86_64.rpm

wget http://mirrors.coreix.net/elrepo-archive-archive/kernel/el7/x86_64/RPMS/kernel-lt-devel-5.4.208-1.el7.elrepo.x86_64.rpm
wget http://mirrors.coreix.net/elrepo-archive-archive/kernel/el7/x86_64/RPMS/kernel-lt-headers-5.4.208-1.el7.elrepo.x86_64.rpm
wget http://mirrors.coreix.net/elrepo-archive-archive/kernel/el7/x86_64/RPMS/kernel-lt-5.4.208-1.el7.elrepo.x86_64.rpm

查看所有安装的内核包
rpm -qa | grep kernel

卸载版本过高的包
rpm -e kernel-lt-devel-5.4.226-1.el7.elrepo.x86_64

rpm -ivh kernel-lt-devel-5.4.208-1.el7.elrepo.x86_64.rpm

rpm -ivh kernel-lt-headers-5.4.208-1.el7.elrepo.x86_64.rpm

rpm -ivh kernel-lt-5.4.208-1.el7.elrepo.x86_64.rpm

查看启动顺序
cat /etc/grub2.cfg | grep menuentry|awk -F "\'" '$1=="menuentry " {print i++ " : " $2}'
设置启动顺序

grub2-set-default 0

验证设置是否成功
grub2-editenv list

重启生效
reboot