CentOS 7 升级 Linux 内核

一、YUM升级内核

1、更新仓库

yum -y update

2、用 ELRepo 仓库

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

3、查看可用的系统内核包(可以看到，只有 4.4 和 4.20 两个版本可以使用)

[root@localhost ~]# yum --disablerepo="*" --enablerepo="elrepo-kernel" list available
已加载插件：fastestmirror, langpacks
Loading mirror speeds from cached hostfile
 * elrepo-kernel: mirrors.neusoft.edu.cn
elrepo-kernel                                                                                                                                         | 2.9 kB  ::
elrepo-kernel/primary_db                                                                                                                              | 1.8 MB  ::
可安装的软件包
kernel-lt.x86_64                                                                      4.4.-.el7.elrepo                                                      elrepo-kernel
kernel-lt-devel.x86_64                                                                4.4.-.el7.elrepo                                                      elrepo-kernel
kernel-lt-doc.noarch                                                                  4.4.-.el7.elrepo                                                      elrepo-kernel
kernel-lt-headers.x86_64                                                              4.4.-.el7.elrepo                                                      elrepo-kernel
kernel-lt-tools.x86_64                                                                4.4.-.el7.elrepo                                                      elrepo-kernel
kernel-lt-tools-libs.x86_64                                                           4.4.-.el7.elrepo                                                      elrepo-kernel
kernel-lt-tools-libs-devel.x86_64                                                     4.4.-.el7.elrepo                                                      elrepo-kernel
kernel-ml.x86_64                                                                      4.20.-.el7.elrepo                                                       elrepo-kernel
kernel-ml-devel.x86_64                                                                4.20.-.el7.elrepo                                                       elrepo-kernel
kernel-ml-doc.noarch                                                                  4.20.-.el7.elrepo                                                       elrepo-kernel
kernel-ml-headers.x86_64                                                              4.20.-.el7.elrepo                                                       elrepo-kernel
kernel-ml-tools.x86_64                                                                4.20.-.el7.elrepo                                                       elrepo-kernel
kernel-ml-tools-libs.x86_64                                                           4.20.-.el7.elrepo                                                       elrepo-kernel
kernel-ml-tools-libs-devel.x86_64                                                     4.20.-.el7.elrepo                                                       elrepo-kernel
perf.x86_64                                                                           4.20.-.el7.elrepo                                                       elrepo-kernel
python-perf.x86_64                                                                    4.20.-.el7.elrepo                                                       elrepo-kerne

4、安装最新内核

yum --enablerepo=elrepo-kernel install kernel-ml

5.查看系统上的所有可以内核

[root@localhost ~]#  awk -F\' '$=="menuentry " {print i++ " : " $}' /etc/grub2.cfg
 : CentOS Linux (4.20.-.el7.elrepo.x86_64)  (Core)
 : CentOS Linux (3.10.-957.1..el7.x86_64)  (Core)
 : CentOS Linux (3.10.-.el7.x86_64)  (Core)
 : CentOS Linux (-rescue-87b5a0a60fc351ad00a94aa3c5b30baa)  (Core)

6.设置 grub2,并生成grub配置文件

[root@localhost ~]# grub2-set-default
[root@localhost ~]# grub2-mkconfig -o /boot/grub2/grub.cfg
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-4.20.-.el7.elrepo.x86_64
Found initrd image: /boot/initramfs-4.20.-.el7.elrepo.x86_64.img
Found linux image: /boot/vmlinuz-3.10.-957.1..el7.x86_64
Found initrd image: /boot/initramfs-3.10.-957.1..el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.-.el7.x86_64
Found initrd image: /boot/initramfs-3.10.-.el7.x86_64.img
Found linux image: /boot/vmlinuz--rescue-87b5a0a60fc351ad00a94aa3c5b30baa
Found initrd image: /boot/initramfs--rescue-87b5a0a60fc351ad00a94aa3c5b30baa.img
done

7.重启并查看当前内核

[root@localhost ~]# reboot
[root@localhost ~]# uname -r
4.20.-.el7.elrepo.x86_64

二、离线RPM包安装内核

1.下载RPM包

https://elrepo.org/linux/kernel/el7/x86_64/RPMS/ #选择自己想要的版本下载对应的
[root@localhost ~]# wget https://elrepo.org/linux/kernel/el7/x86_64/RPMS/kernel-lt-4.4.206-1.el7.elrepo.x86_64.rpm
[root@localhost ~]# wget https://elrepo.org/linux/kernel/el7/x86_64/RPMS/kernel-lt-devel-4.4.206-1.el7.elrepo.x86_64.rpm

 2.安装RPM包

[root@localhost ~]# yum localinstall -y kernel-lt-4.4.-.el7.elrepo.x86_64.rpm kernel-lt-devel-4.4.-.el7.elrepo.x86_64.rpm 

3.查看当前系统上的所有可用内核启动项

非 UEFI 设备（Legacy）：
[root@localhost ~]# awk -F\' '$=="menuentry " {print i++ " : " $}' /etc/grub2.cfg
 : CentOS Linux (4.4.-.el7.elrepo.x86_64)  (Core)
 : CentOS Linux (3.10.-.el7.x86_64)  (Core)
 : CentOS Linux (-rescue-395aa029d0cca260e8304b6bf0846236)  (Core)
UEFI 设备（Legacy）：
[root@localhost ~]#  awk -F\' '$=="menuentry " {print i++ " : " $}'  /boot/efi/EFI/centos/grub.cfg
 : CentOS Linux (4.4.-.el7.elrepo.x86_64)  (Core)
 : CentOS Linux (3.10.-.el7.x86_64)  (Core)
 : CentOS Linux (-rescue-e2c56988fd1743ab9d8902c5dd4d4cc1)  (Core)
#注意文件名称

4.修改默认启动项

默认启动项由/etc/default/grub中的GRUB_DEFAULT控制。

如果GRUB_DEFAULT=saved，则该参数将存储在/boot/grub2/grubenv中。可使用grub2-editenv list查看：

[root@localhost ~]# grub2-editenv list
saved_entry=CentOS Linux (3.10.-.el7.x86_64)  (Core)

通过grub2-set-default命令修改默认启动项。由之前的输出可知 CentOS Linux (4.4.206-1.el7.elrepo.x86_64) 7 (Core) 的启动序号为0

1).通过启动序号设置4.4.205-1.el7.elrepo.x86_64为默认启动内核

[root@localhost ~]# grub2-editenv list
saved_entry=0  #0为4.4内核启动序号

重启并查看内核版本

[root@localhost ~]# reboot
[root@localhost ~]# uname -r
4.4.-.el7.elrepo.x86_64

2).通过内核名称设置4.4.205-1.el7.elrepo.x86_64为默认启动内核

恢复至3.10内核

[root@localhost ~]# grep "^menuentry"  /boot/grub2/grub.cfg
[root@localhost ~]# grub2-set-default
[root@localhost ~]# grub2-editenv list
saved_entry=
[root@localhost ~]# reboot
[root@localhost ~]# uname -r
3.10.-.el7.x86_64

通过内核名称设置4.4.205-1.el7.elrepo.x86_64为默认启动内核

[root@localhost ~]# grub2-set-default "CentOS Linux (4.4.206-1.el7.elrepo.x86_64) 7 (Core)"
[root@localhost ~]# grub2-editenv list
saved_entry=CentOS Linux (4.4.-.el7.elrepo.x86_64)  (Core)

重启查看内核版本

[root@localhost ~]# reboot
[root@localhost ~]# uname -r
4.4.-.el7.elrepo.x86_64

本文yum安装完全抄自：https://blog.csdn.net/kikajack/article/details/79396793