Upgrade kernel of CentOS 7 to latest version
Previously I was writing about upgrading system now I will show how to upgrade the CentOS7 kernel to the latest version. Using ELRepo repository we can get easy kernel updates. ELRepo is focused on the packages related to hardware, including filesystem drivers, graphic drivers, network drivers, sound card drivers, webcam, and others.
Instructions
Check the current kernel version.
# uname -sr
Linux 4.11.3-1.el7.elrepo.x86_64
If we now go to
To enable the ELRepo repository on CentOS 7, do
rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
rpm -Uvh http://www.elrepo.org/elrepo-release-7.0-3.el7.elrepo.noarch.rpm
Next, install the latest mainline stable kernel
yum --enablerepo=elrepo-kernel install kernel-ml
I had this output of that command
# yum --enablerepo=elrepo-kernel install kernel-ml
Loaded plugins: fastestmirror, langpacks
elrepo-kernel | 2.9 kB 00:00:00
elrepo-kernel/primary_db | 1.7 MB 00:00:01
Loading mirror speeds from cached hostfile
* base: mirror.reconn.ru
* elrepo: nl.mirror.babylon.network
* elrepo-kernel: nl.mirror.babylon.network
* epel: mirror.logol.ru
* extras: mirror.reconn.ru
* updates: mirror.reconn.ru
Resolving Dependencies
--> Running transaction check
---> Package kernel-ml.x86_64 0:4.15.8-1.el7.elrepo will be installed
--> Finished Dependency Resolution
Dependencies Resolved
==============================================================================================================================================================================================
Package Arch Version Repository Size
==============================================================================================================================================================================================
Installing:
kernel-ml x86_64 4.15.8-1.el7.elrepo elrepo-kernel 44 M
Transaction Summary
==============================================================================================================================================================================================
Install 1 Package
Total download size: 44 M
Installed size: 198 M
Is this ok [y/d/N]: y
Downloading packages:
kernel-ml-4.15.8-1.el7.elrepo.x86_64.rpm | 44 MB 00:00:05
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
Installing : kernel-ml-4.15.8-1.el7.elrepo.x86_64 1/1
Verifying : kernel-ml-4.15.8-1.el7.elrepo.x86_64 1/1
Installed:
kernel-ml.x86_64 0:4.15.8-1.el7.elrepo
Complete!
Next, reboot your machine to apply the latest kernel
systemctl reboot
If you just reboot the system and run command to check the version of your kernel
# uname -sr
Linux 4.11.3-1.el7.elrepo.x86_64
You will see your current kernel. WTF? But I updated it. Your system will be updated but to run the system with new kernel need configure Grub loader.
Let’s check the current configuration
# awk -F\' '$1=="menuentry " {print i++ " : " $2}' /etc/grub2.cfg
0 : CentOS Linux (4.15.8-1.el7.elrepo.x86_64) 7 (Core)
1 : CentOS Linux (4.11.3-1.el7.elrepo.x86_64) 7 (Core)
2 : CentOS Linux (0-rescue-d39b765b9cf142baa7ed9ca6543375de) 7 (Core)
As you can see the new kernel has the second option in the loading process. We want to use kernel 4.15 as our default, so you can use the following command to make this happen.
grub2-set-default 0
When you want to revert back to the old kernel,
you can change the value of the grub2-set-default command to 1.
Finally, generate the grub2 config with gurb2-mkconfig command, and then reboot the server.
grub2-mkconfig -o /boot/grub2/grub.cfg
systemctl reboot
After system will load check again the kernel version
# uname -sr
Linux 4.15.8-1.el7.elrepo.x86_64
Excellent! We have the latest kernel.
Of course, don’t do this procedure on a system with users.