Upgrade the kernel by installing xanmod kernel is very convenient. Read more here: https://xanmod.org/
echo 'deb http://deb.xanmod.org releases main' | sudo tee /etc/apt/sources.list.d/xanmod-kernel.list
wget -qO - https://dl.xanmod.org/gpg.key | sudo apt-key --keyring /etc/apt/trusted.gpg.d/xanmod-kernel.gpg add -
sudo apt update && sudo apt install linux-xanmod
Reboot after installation.
I was trying to install kernel 5.15 on a ASUS laptop in order to install asusctl and supergfxctl After upgrade to kernel 5.15 by adding Ubuntu proposed PPA and apt, as described by this: https://www.linuxcapable.com/how-to-install-linux-kernel-5-15-on-ubuntu-20-04/, I found WiFi and touchpad stop working.
The proper way is to download kernel files and install by dpkg
cd /tmp/
wget -c https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.15.30/amd64/linux-headers-5.15.30-051530-generic_5.15.30-051530.202203190935_amd64.deb
wget -c https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.15.30/amd64/linux-headers-5.15.30-051530_5.15.30-051530.202203190935_all.deb
wget -c https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.15.30/amd64/linux-image-unsigned-5.15.30-051530-generic_5.15.30-051530.202203190935_amd64.deb
wget -c https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.15.30/amd64/linux-modules-5.15.30-051530-generic_5.15.30-051530.202203190935_amd64.deb
when sudo dpkg -i *.deb it shows errors which lacks libssl3 and newer libc6. libssl3 is required by kernel 5.15.7+ and only comes with 22.04. Before upgrading to 22.04, we can add the Ubuntu 22.04 repo:
sudo add-apt-repository "deb http://ca.archive.ubuntu.com/ubuntu jammy main"
then do the installation
sudo apt install libssl3
sudo apt --fix-broken install
sudo dpkg -i *.deb
and then remove the repo:
sudo add-apt-repository --remove "deb http://ca.archive.ubuntu.com/ubuntu jammy main"
If you try to install libc-dev and libc6-dev in the future, it'll complain about it unless you have the jelly repo. Just add it back, install, and remove.