一、前言

之前發現編譯http2.4的時候，操作正常，http服務啟動不起來，困擾了半天，經過查資料是由於linux 核心版本的問題導致的，所以記錄下解決過程

1. 檢視當前核心版本

一、升級前操作

1. 檢視當前核心版本

1. 檢視當前核心版本

[root@VM_0_17_centos ~]# uname -r
3.10.0-862.el7.x86_64

2. 安裝 ELRepo 源

ELRepo官網

(1) 匯入公共祕鑰

rpm --importhttps://www.elrepo.org/RPM-GPG-KEY-elrepo.org

[root@VM_0_17_centos ~]# rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
 

(2) 安裝 ELRepo 的 YUM 源

rpm -Uvhhttps://www.elrepo.org/elrepo-release-7.0-3.el7.elrepo.noarch.rpm

[root@VM_0_17_centos ~]# rpm -Uvh https://www.elrepo.org/elrepo-release-7.0-3.el7.elrepo.noarch.rpm
Retrieving https://www.elrepo.org/elrepo-release-7.0-3.el7.elrepo.noarch.rpm
Preparing... ################################# [100%]
Updating / installing... 1:elrepo-release-7.0-3.el7.elrepo  ################################# [100%]
 

二、安裝核心

1. 通過 YUM 安裝

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

預設安裝 mainline 版本（主線版本）。

[root@VM_0_17_centos ~]# yum --enablerepo=elrepo-kernel install kernel-ml-devel kernel-ml
Loaded plugins: fastestmirror, langpacks
Determining fastest mirrors
 * elrepo: mirror-hk.koddos.net
 * elrepo-kernel: mirror-hk.koddos.net
elrepo | 2.9 kB  00:00:00
elrepo-kernel | 2.9 kB  00:00:00
(1/2): elrepo/primary_db | 477 kB  00:00:00
(2/2): elrepo-kernel/primary_db | 1.8 MB  00:00:00
Resolving Dependencies
--> Running transaction check
---> Package kernel-ml.x86_64 0:5.3.7-1.el7.elrepo will be installed
---> Package kernel-ml-devel.x86_64 0:5.3.7-1.el7.elrepo will be installed
--> Finished Dependency Resolution

Dependencies Resolved

=====================================================================================================================================================================
 Package Arch Version Repository Size
=====================================================================================================================================================================
Installing:
 kernel-ml x86_64 5.3.7-1.el7.elrepo elrepo-kernel 48 M
 kernel-ml-devel x86_64 5.3.7-1.el7.elrepo elrepo-kernel 13 M

Transaction Summary
=====================================================================================================================================================================
Install  2 Packages

Total download size: 61 M
Installed size: 264 M
Is this ok [y/d/N]: y
Downloading packages:
(1/2): kernel-ml-devel-5.3.7-1.el7.elrepo.x86_64.rpm |  13 MB  00:00:16
(2/2): kernel-ml-5.3.7-1.el7.elrepo.x86_64.rpm |  48 MB  00:01:16
---------------------------------------------------------------------------------------------------------------------------------------------------------------------
Total 807 kB/s |  61 MB  00:01:16
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
Warning: RPMDB altered outside of yum.
  Installing : kernel-ml-5.3.7-1.el7.elrepo.x86_64 1/2
  Installing : kernel-ml-devel-5.3.7-1.el7.elrepo.x86_64 2/2
  Verifying  : kernel-ml-devel-5.3.7-1.el7.elrepo.x86_64 1/2
  Verifying  : kernel-ml-5.3.7-1.el7.elrepo.x86_64 2/2

Installed:
  kernel-ml.x86_64 0:5.3.7-1.el7.elrepo kernel-ml-devel.x86_64 0:5.3.7-1.el7.elrepo

Complete
 
!

2. 檢視已安裝的核心版本

rpm -qa kernel*

[root@VM_0_17_centos ~]# rpm -qa kernel*
kernel-headers-3.10.0-957.1.3.el7.x86_64
kernel-3.10.0-862.el7.x86_64
kernel-ml-devel-5.3.7-1.el7.elrepo.x86_64
kernel-tools-libs-3.10.0-862.el7.x86_64
kernel-tools-3.10.0-862.el7.x86_64
kernel-devel-3.10.0-862.el7.x86_64
kernel-ml-5.3.7-1.el7.elrepo.x86_64

rpm -qa | grep -i kernel

[root@VM_0_17_centos ~]# rpm -qa | grep -i kernel
kernel-headers-3.10.0-957.1.3.el7.x86_64
kernel-3.10.0-862.el7.x86_64
abrt-addon-kerneloops-2.1.11-50.el7.centos.x86_64
kernel-ml-devel-5.3.7-1.el7.elrepo.x86_64
kernel-tools-libs-3.10.0-862.el7.x86_64
kernel-tools-3.10.0-862.el7.x86_64
kernel-devel-3.10.0-862.el7.x86_64
kernel-ml-5.3.7-1.el7.elrepo.x86_64

3. 查詢新安裝的核心完整名稱

cat /boot/grub2/grub.cfg | grep menuentry

[root@VM_0_17_centos ~]# cat /boot/grub2/grub.cfg | grep menuentry
if [ x"${feature_menuentry_id}" = xy ]; then
  menuentry_id_option="--id"
  menuentry_id_option=""
export menuentry_id_option
menuentry 'CentOS Linux (5.3.7-1.el7.elrepo.x86_64) 7 (Core)' --class centos --class gnu-linux --class gnu --class os --unrestricted $menuentry_id_option 'gnulinux-3.10.0-862.el7.x86_64-advanced-21dbe030-aa71-4b3a-8610-3b942dd447fa' {
menuentry 'CentOS Linux (3.10.0-862.el7.x86_64) 7 (Core)' --class centos --class gnu-linux --class gnu --class os --unrestricted $menuentry_id_option 'gnulinux-3.10.0-862.el7.x86_64-advanced-21dbe030-aa71-4b3a-8610-3b942dd447fa' {
menuentry 'CentOS Linux (0-rescue-c28d40cbc8e3adcb4e32d9779a77b39e) 7 (Core)' --class centos --class gnu-linux --class gnu --class os --unrestricted $menuentry_id_option 'gnulinux-0-rescue-c28d40cbc8e3adcb4e32d9779a77b39e-advanced-21dbe030-aa71-4b3a-8610-3b942dd447fa' {

三、核心切換

1. 更改預設核心

命令2選1：

(1)grub2-set-default 0

預設啟動順序應該為1，升級後核心是往前面插入，為0。

[root@VM_0_17_centos ~]# grub2-set-default 0

(2)grub2-set-default ' '

[root@VM_0_17_centos ~]# grub2-set-default 'CentOS Linux (5.3.7-1.el7.elrepo.x86_64) 7 (Core)'

2. 檢視預設啟動核心是否更換成功

grub2-editenv list

[root@VM_0_17_centos ~]# grub2-editenv list
saved_entry=CentOS Linux (5.3.7-1.el7.elrepo.x86_64) 7 (Core)

三、啟用核心

1. 重啟系統

reboot

[root@VM_0_17_centos ~]# reboot

2. 檢視核心版本

uname -r

[root@VM_0_17_centos ~]# uname -r
5.3.7-1.el7.elrepo.x86_64