This guide walks readers through upgrading an Ubuntu 20.04 LTS system from the default 5.4 kernel to the newer 5.18 mainline release, explaining that the change brings better hardware support and security fixes. It begins by instructing users to update their package lists, install build-essential tools, DKMS, and matching headers so that optional modules can be rebuilt after the upgrade. The steps then show how to download three specific .deb packages from Ubuntu’s mainline repository—headers, generic headers, and an unsigned image—and install them with dpkg, followed by a dependency check with apt‑get if necessary. Finally, the tutorial covers how to confirm the new kernel with uname, reboot into it via GRUB or recovery mode, and provides commands for rolling back should any driver or boot issues arise.

Install Linux Kernel 5.18 on Ubuntu 20.04 LTS

If you’re still running the stock 5.4 kernel on your trusty 20.04 machine and need the new features or bug fixes in 5.18, this guide shows you how to get it up and running without turning your system into a broken mess.

Why bother with 5.18?

I’ve seen users complain that their Wi‑Fi stalls after a firmware upgrade while they’re stuck on an old kernel. Kernel 5.18 brings better hardware support for newer GPUs, improved power management, and the latest security patches. If you need one of those, upgrading is worth it.

1. Prepare Your System

sudo apt update
sudo apt upgrade -y
sudo apt install build-essential dkms linux-headers-generic

The build-essential package gives you the compiler and libraries you might need for optional DKMS modules. linux-headers-generic ensures you have headers that match whatever kernel is currently active; they’ll be handy if you later need to rebuild a module.

2. Download the Kernel Packages

Head over to the official mainline builds: https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.18/ . Pick three files:

• linux-headers-5.18.x_all.deb
• linux-headers-5.18.x_generic_amd64.deb (or _i386.deb)
• linux-image-unsigned-5.18.x_generic_amd64.deb

On the command line, something like:

wget https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.18/$(uname -m)/linux-headers-5.18.*_all.deb
wget https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.18/$(uname -m)/linux-headers-5.18.*_generic_$(dpkg --print-architecture).deb
wget https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.18/$(uname -m)/linux-image-unsigned-5.18.*_generic_$(dpkg --print-architecture).deb

Those are the only packages you actually need; no meta‑packages or signed images for 20.04, because we’re installing a “mainline” kernel manually.

3. Install the Kernel

First install the header files so that any DKMS modules can compile against the new headers:

sudo dpkg -i linux-headers-5.18.*_all.deb
sudo dpkg -i linux-headers-5.18.*_generic_$(dpkg --print-architecture).deb

Then install the image:

sudo dpkg -i linux-image-unsigned-5.18.*_generic_$(dpkg --print-architecture).deb

If dpkg complains about missing dependencies, run:

sudo apt-get -f install

The dpkg commands will copy the files into /boot, register them with GRUB, and update the initramfs. Running apt‑get -f install pulls in any runtime dependencies you might have missed.

4. Verify

After installation, run:

uname -r

You should see something like 5.18.0-1-generic. If that shows up, you’re good to go. Now reboot:

sudo reboot

During the boot menu, if you’re not automatically taken to the new kernel, press Esc or Shift at startup to bring up GRUB and select “Advanced options for Ubuntu” => “5.18.x generic”.

5. Rollback if Things Go South

If you hit a wall—boot loop, missing drivers—re‑boot into recovery mode and choose the previous kernel from the GRUB menu. Once back in, you can remove the new kernel packages:

sudo dpkg -r linux-image-unsigned-5.18.*_generic_$(dpkg --print-architecture)
sudo dpkg -r linux-headers-5.18.*_all
sudo dpkg -r linux-headers-5.18.*_generic_$(dpkg --print-architecture)

Then run sudo update-grub to clean up.

That’s the whole dance: pull the right debs, install them, reboot, and if you’re unlucky, roll back. No fancy scripts or third‑party PPA required.