Welcome to the guide!

• This guide is only useful for those with grub at the moment.
• DO NOT USE THIS GUIDE IF YOU DON'T KNOW WHAT YOU'RE DOING, YOU MAY BRICK YOUR LINUX INSTALLATION!
• DO NOT DELETE A BACKUP KERNEL! ALWAYS HAVE ONE! MAKE A BACKUP BEFORE ATTEMPTING!
• READ THE LICENSE BEFORE PROCEEDING!

Dependancies

• sudo / doas (replace sudo with doas if using doas)
• cmake (for building)
• dracut (for initramfs)
• zstd (to increase compatibility)
• tar (to extract)
• grub (required to be installed)
• gcc (required)

Understanding

/usr/src/ - Folder of different linux kernel(s) folders containing source code.

~ - Your user folder.

When redoing the kernel using dracut and grub-mkconfig the kernel will not be replaced, instead it'll be renamed to old so that you'll have only one back up.

Prepare for the installation

make sure you have your /boot directory properly mounted before proceeding (usually it is)

wget the kernel version of your choosing... from the v5.x directory.

wget https://mirrors.edge.kernel.org/pub/linux/kernel/v5.x/linux-<version>.tar.xz

prepare the source code files:

sudo tar -xvf linux-<version>.tar.xz -C /usr/src/

Saving linux-<version>.tar.xz is probably a good idea incase patches etc.. do not work.

Install patches into linux src manually

Please make sure that the patches are for your specific kernel version (5.15.xx for example) otherwise your kernel will be unable to boot.

To patch the kernel with your specific patches:

cd /usr/src/linux-<version>

sudo patch -p1 < /<directory containing patches>/<yourpatch>.patch

Installation

If you've skipped patching the linux kernel:

cd /usr/src/linux-<version>

Configure the kernel (Optional but highly recommended):

sudo make menuconfig

Build the kernel:

sudo make -j<number of physical cpu's>

Install the modules and install the built kernel:

sudo make modules_install && sudo make install

Finishing up the installation

Generate initramfs:

sudo dracut --hostonly --force --kver <version>

Re-generate the grub-config:

sudo grub-mkconfig -o /boot/grub/grub.cfg

Cleaning up

Remove the kernel tar:

sudo rm ~/linux-<version>.tar.xz

(Not Recommended at ALL) Remove linux-<version> from /usr/src/ for whatever reason (This is the source to build your kernel with your custom patches and config, be very careful about the rm -rf and directory.. seriously don't do this):

sudo rm -rf /usr/src/linux-<version>