Upgrading the Kernel on CentOS 8.x / AlmaLinux 8.x / Rocky Linux 8.x
Before proceeding , as always make sue you have a snapshot or backup or your system.
The article was written on 26 June 2021. The current Kernel versions where longterm:5.4.128 and stable:5.12.13.
To update the Kernel, we will use a fairly reliable external repository called elrepo.
As opposed to Red Hat, CentOS / AlmaLinux / Rocky Linux allows the use of elrepo, a third-party repository that makes the upgrade to a recent version a kernel.
Step 1. Install elrepo
Run: rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
The screen will take a second then return you to a prompt, that is normal.
Run: dnf install https://www.elrepo.org/elrepo-release-8.el8.elrepo.noarch.rpm
Enter "y", and Press "Enter"
You should see the below:
We are going to use nano to edit some test files, so now is a good time to make sure you have it installed.
If not take a quick second to install it using: dnf install nano
If you use vi, that is fine also.
But all screenshots show nano.
Step 2. Enabling elrepo to install updated kernel(s)
Run: cd /etc/yum.repos.d
then
Run: ls
You should see a repo named elrepo.repo
Run: nano elrepo.repo
Scroll down to the section [elrepo-kernel]
Change enabled=0 to enabled=1
elrepo is not configured to install, and auto update kernels when you run dnf update.
Step3. Installing New Kernel
Now there are 2 kernel versions available: longterm and stable
If you are not sure what these are, take a quick visit to The Linux Kernel Archives at : https://www.kernel.org/
To Install the recommended longterm kernel - Run: dnf install kernel-lt
Or if you prefer the latest stable kernel - Run: dnf install kernel-ml
In the example below, we install the longterm kernel:
Enter "y", and Press "Enter"
Installation:
Step 4. Set Default Kernel in Grub
To make the newly-installed version the default boot option, you will have to modify the GRUB configuration as follows:
Run: cd /etc/default
then
Run: nano grub
You will see:
Change GRUB_DEFAULT=saved to GRUB_DEFAULT=0 (ZERO, NOT o)
Next, we are going to update the kernel boot configuration.
Run: grub2-mkconfig -o /boot/grub2/grub.cfg
On a new system, you should see:
Then we just need to Reboot the system, Run: shutdown -r now
After it's rebooted, just SSH or log back in.
Run: uname -r
You should see the new kernel version:
Which shows the current longterm kernel version was installed, and is running.
Congrats You Are Done!
Now when you run dnf update, if there is a kernel update, it will update as well.
If you do NOT want to automatically update the kernel for some reason, you can disable it by changing the 1 back to a 0 under [elrepo-kernel].
Then to manually update the kernel you would have to Run: dnf --enablerepo=elrepo-kernel install kernel-lt (or kernel-ml)
Last Updated: 26 June 2021