Centos 7 升级内核版本为 5.12.11​

# 查看当前内核
$ uname -sr
Linux 3.10.0-1160.25.1.el7.x86_64

# 查看操作系统版本
$ cat /etc/redhat-release
CentOS Linux release 7.9.2009 (Core)

# 导入 ELRepo 仓库的公共密钥
$ rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org

# 安装 ELRepo 仓库的 yum 源
$ yum install -y https://www.elrepo.org/elrepo-release-7.el7.elrepo.noarch.rpm

# 替换为清华 ELRepo 源
$ sed -i "s/mirrorlist=/#mirrorlist=/g" /etc/yum.repos.d/elrepo.repo
$ sed -i "s#elrepo.org/linux#mirrors.tuna.tsinghua.edu.cn/elrepo#g" /etc/yum.repos.d/elrepo.repo

# (可选) 更新 yum 缓存
$ yum makecache

# 查看可用的内核版本，kernel-ml（mainline stable）：稳定主线版本，kernel-lt（long term support）：长期支持版本
$ yum --disablerepo="*" --enablerepo="elrepo-kernel" list available
已加载插件：fastestmirror, langpacks
Repository base is listed more than once in the configuration
Repository updates is listed more than once in the configuration
Repository extras is listed more than once in the configuration
Repository centosplus is listed more than once in the configuration
Loading mirror speeds from cached hostfile
 * elrepo-kernel: linux-mirrors.fnal.gov
可安装的软件包
kernel-lt.x86_64                           5.4.127-1.el7.elrepo          elrepo-kernel
kernel-lt-devel.x86_64                     5.4.127-1.el7.elrepo          elrepo-kernel
kernel-lt-doc.noarch                       5.4.127-1.el7.elrepo          elrepo-kernel
kernel-lt-headers.x86_64                   5.4.127-1.el7.elrepo          elrepo-kernel
kernel-lt-tools.x86_64                     5.4.127-1.el7.elrepo          elrepo-kernel
kernel-lt-tools-libs.x86_64                5.4.127-1.el7.elrepo          elrepo-kernel
kernel-lt-tools-libs-devel.x86_64          5.4.127-1.el7.elrepo          elrepo-kernel
kernel-ml.x86_64                           5.12.12-1.el7.elrepo          elrepo-kernel
kernel-ml-devel.x86_64                     5.12.12-1.el7.elrepo          elrepo-kernel
kernel-ml-doc.noarch                       5.12.12-1.el7.elrepo          elrepo-kernel
kernel-ml-headers.x86_64                   5.12.12-1.el7.elrepo          elrepo-kernel
kernel-ml-tools.x86_64                     5.12.12-1.el7.elrepo          elrepo-kernel
kernel-ml-tools-libs.x86_64                5.12.12-1.el7.elrepo          elrepo-kernel
kernel-ml-tools-libs-devel.x86_64          5.12.12-1.el7.elrepo          elrepo-kernel
perf.x86_64                                5.12.12-1.el7.elrepo          elrepo-kernel
python-perf.x86_64                         5.12.12-1.el7.elrepo          elrepo-kernel

# 升级为主线版本
$ yum --enablerepo=elrepo-kernel install kernel-ml -y

# 查看可用内核版本及启动顺序
$ sudo awk -F\' '$1=="menuentry " {print i++ " : " $2}' /boot/grub2/grub.cfg

# 查看启动顺序
$ yum install -y grub2-pc
$ grub2-editenv list

# 设置开机启动
$ grub2-set-default 0
或者
$ grub2-mkconfig -o /boot/grub2/grub.cfg

# 重启生效
$ reboot

# 重启后查看内核版本
$ uname -sr