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Upgrade Kernel on CentOS 8.x, AlmaLinux 8.x and Rocky Linux 8.x

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:

Delete the line: GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"

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: 2021 June 26