Kernel downgrade on Raspberry Pi OS

Instructions for downgrading a kernel while keeping updated userland of Raspberry Pi OS.

Kernel packages explained

Kernel package name is "raspberrypi-kernel". It contains /boot/kernel8.img image as well as kernel modules.

Package version number is a release date and does not match kernel version inside. During my research i looked through a bunch of package versions and documented their contents:

deb version	Kernel version	Download
20230405	6.1.21	[32bit] [64bit]
20220331	5.15.32	[32bit] [64bit]
20220328	5.15.30	[32bit] [64bit]
20220308	5.10.103	[32bit] [64bit]
20220120	5.10.92	[32bit] [64bit]
20211118	5.10.63	[32bit] [64bit]

There are more versions available in package archive if you're looking for a specific version.

Installing kernel package

Download a kernel package to a local file system, e.g.:

wget https://archive.raspberrypi.org/debian/pool/main/r/raspberrypi-firmware/raspberrypi-kernel_1.20220308-2_arm64.deb

Install the package:

dpkg -i raspberrypi-kernel_1.20220308-2_arm64.deb

Newer versions of bootloader are looking for kernel image in a different path, so make a copy manually:

cp /boot/kernel8.img /boot/firmware/kernel8.img

Depending on your hardware revision and bootloader version, the filename might be different. Consult official documentation if your setup boots a "wrong" version of the kernel.

Prevent apt from upgrading kernel

Instruct apt to hold the currently installed kernel version:

apt-mark hold raspberrypi-kernel

Notes

On my Pi4B downgrading the kernel resulted in broken Wayland. Since my usecase does not require graphical session, i did not investigate ways to fix it.

Switching to X11 using raspi-config resulted in working graphical environment.