centos7在线升级内核

使用 uname -sr 查看自己内核版本号：

[root@localhost ~]# uname -sr Linux 3.10.0-862.el7.x86_64 然后我们在浏览器中输入 www.kernel.org，查看centos,最新内核版本为：4.18

一：、安装elrepo的yum源 elrepo是CentOS十分有用的稳定的软件源，这是一个第三方仓库，可以将内核升级到最新版本。我们可以在命令行中输入：

首先导入public key

[root@localhost ~]# rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org [root@localhost ~]# rpm -Uvh http://www.elrepo.org/elrepo-release-7.0-2.el7.elrepo.noarch.rpm Retrieving http://www.elrepo.org/elrepo-release-7.0-2.el7.elrepo.noarch.rpm Retrieving http://elrepo.org/elrepo-release-7.0-3.el7.elrepo.noarch.rpm Preparing... ################################# [100%] Updating / installing... 1:elrepo-release-7.0-3.el7.elrepo ################################# [100%] 仓库启用后，我们可以使用下面的命令列出可用的内核相关包：

yum --disablerepo="*" --enablerepo="elrepo-kernel" list available

Loaded plugins: fastestmirror, langpacks Repository 'QJC' is missing name in configuration, using id Loading mirror speeds from cached hostfile

• elrepo-kernel: hkg.mirror.rackspace.com elrepo-kernel | 2.9 kB 00:00:00
  elrepo-kernel/primary_db | 1.8 MB 00:00:00
  Available Packages kernel-lt.x86_64 4.4.152-1.el7.elrepo elrepo-kernel kernel-lt-devel.x86_64 4.4.152-1.el7.elrepo elrepo-kernel kernel-lt-doc.noarch 4.4.152-1.el7.elrepo elrepo-kernel kernel-lt-headers.x86_64 4.4.152-1.el7.elrepo elrepo-kernel kernel-lt-tools.x86_64 4.4.152-1.el7.elrepo elrepo-kernel kernel-lt-tools-libs.x86_64 4.4.152-1.el7.elrepo elrepo-kernel kernel-lt-tools-libs-devel.x86_64 4.4.152-1.el7.elrepo elrepo-kernel kernel-ml.x86_64 4.18.5-1.el7.elrepo elrepo-kernel kernel-ml-devel.x86_64 4.18.5-1.el7.elrepo elrepo-kernel kernel-ml-doc.noarch 4.18.5-1.el7.elrepo elrepo-kernel kernel-ml-headers.x86_64 4.18.5-1.el7.elrepo elrepo-kernel kernel-ml-tools.x86_64 4.18.5-1.el7.elrepo elrepo-kernel kernel-ml-tools-libs.x86_64 4.18.5-1.el7.elrepo elrepo-kernel kernel-ml-tools-libs-devel.x86_64 4.18.5-1.el7.elrepo elrepo-kernel perf.x86_64 4.18.5-1.el7.elrepo elrepo-kernel python-perf.x86_64 4.18.5-1.el7.elrepo elrepo-kernel 二：升级内核 在yum的elrepo源中有ml和lt两种内核，其中ml(mainline)为最新版本的内核，lt为长期支持的内核。

如果要安装ml内核，使用如下命令：

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

如果要安装lt内核，使用如下命令：

yum --enablerepo=elrepo-kernel -y install kernel-lt kernel-lt-devel

在此我们安装的是ml内核，如下：

yum --enablerepo=elrepo-kernel install kernel-ml Loaded plugins: fastestmirror, langpacks Repository 'QJC' is missing name in configuration, using id Loading mirror speeds from cached hostfile

• elrepo: hkg.mirror.rackspace.com
• elrepo-kernel: hkg.mirror.rackspace.com file:///media/repodata/repomd.xml: [Errno 14] curl#37 - "Couldn't open file /media/repodata/repomd.xml" Trying other mirror. elrepo | 2.9 kB 00:00:00
  elrepo/primary_db | 469 kB 00:00:00
  Resolving Dependencies --> Running transaction check ---> Package kernel-ml.x86_64 0:4.18.5-1.el7.elrepo will be installed --> Finished Dependency Resolution

Dependencies Resolved

===================================================================================== Package Arch Version Repository Size

Installing: kernel-ml x86_64 4.18.5-1.el7.elrepo elrepo-kernel 45 M

Transaction Summary

Install 1 Package

Total download size: 45 M Installed size: 203 M Is this ok [y/d/N]: y Downloading packages: kernel-ml-4.18.5-1.el7.elrepo.x86_64.rpm | 45 MB 00:00:04
Running transaction check Running transaction test Transaction test succeeded Running transaction Warning: RPMDB altered outside of yum. Installing : kernel-ml-4.18.5-1.el7.elrepo.x86_64 1/1 Verifying : kernel-ml-4.18.5-1.el7.elrepo.x86_64 1/1

Installed: kernel-ml.x86_64 0:4.18.5-1.el7.elrepo

Complete! 内核升级完毕后，不会立即生效，还需要我们修改grub.conf文件。

方法一：

查看默认启动顺序

awk -F\' '$1=="menuentry " {print $2}' /boot/grub2/grub.cfg

默认启动的顺序是从0开始

grub2-set-default 0 reboot uname -r 方法二： 查看默认 grub2-editenv list 查看所有内核 cat /boot/grub2/grub.cfg | grep menuentry 设置 grub2-set-default "CentOS Linux (4.4.212-1.el7.elrepo.x86_64) 7 (Core)" 再次查看 grub2-editenv list reboot uname -r