How to install kernel in Ubuntu?

First, check your current kernel version:

uname -r

If you want to upgrade or manually install a new kernel, one safe method is using the official Ubuntu Mainline Kernel builds.

To download and install a newer kernel version manually:

• Go to the Ubuntu Kernel PPA:
  https://kernel.ubuntu.com/~kernel-ppa/mainline/

Pick the version you want (e.g., v6.8.x). Right-click the .deb links for your architecture (usually amd64) and copy the link. Now use wget to download the packages. For example:

wget https://kernel.ubuntu.com/~kernel-ppa/mainline/v6.8.2/amd64/linux-headers-6.8.2-060802-generic_6.8.2-060802.202404031234_amd64.deb
wget https://kernel.ubuntu.com/~kernel-ppa/mainline/v6.8.2/amd64/linux-image-6.8.2-060802-generic_6.8.2-060802.202404031234_amd64.deb
wget https://kernel.ubuntu.com/~kernel-ppa/mainline/v6.8.2/amd64/linux-modules-6.8.2-060802-generic_6.8.2-060802.202404031234_amd64.deb

Then install them all together:

sudo dpkg -i *.deb

Once installed, reboot your system:

sudo reboot

After reboot, verify the kernel version:

uname -r

If the new version is shown, the installation was successful.

To remove older kernels later (optional):

dpkg -l | grep linux-image

Then use sudo apt remove to delete unnecessary old versions carefully.

Alternatively, you can use the mainline tool to install new kernels more easily:

First, add the repository:

sudo add-apt-repository ppa:cappelikan/ppa
sudo apt update
sudo apt install mainline -y

Launch it:

mainline