[Tutorial] Building lastest raspberry pi kernel for 64-bit Ubuntu (20.10)

• Original post (Raspberry Pi forum): https://www.raspberrypi.org/forums/viewtopic.php?t=284556
• Original poster: sjevtic

One of the great parts about running Ubuntu is that just about all the Ubuntu-isms you’ve learned for other platforms work here too. Start with these links:

https://wiki.ubuntu.com/Kernel/BuildYourOwnKernel
https://wiki.ubuntu.com/KernelTeam/ARMK … ossCompile
https://wiki.ubuntu.com/KernelTeam/Kern … k_failures
https://askubuntu.com/questions/500095/ … er-version
https://bugs.launchpad.net/ubuntu/+sour … ug/1701756

What follows isn’t very polished, since came out of my notebook verbatim. This is how I built the kernel.

—

First uncomment the relevant line int /etc/apt/sources.list:

deb-src http://ports.ubuntu.com/ubuntu-ports focal-updates main restricted

Update the package database:

apt update

Get the kernel source package, as root in some place where you want it. Alternatively replace $(uname -r) with the version you want. This is probably easiest to do on the target:

apt-get source linux-image-$(uname -r)

If this is on a target, copy it to a dev machine.

Over on the dev machine, hack up your kernel as you please. Then in debian.raspi/changelog, edit the first version number from something like this:

linux-raspi (5.4.0-1019.21) focal; urgency=medium

to something like this:

linux-raspi (5.4.0-1019.21+g34950~20200925) focal; urgency=medium

Note that CONFIG_LOCALVERSION will break the Ubuntu scripts, and EXTRAVERSION in the highest level makefile doesn’t do anything interesting.

Set some environment variables:

export $(dpkg-architecture -aarm64); export CROSS_COMPILE=aarch64-linux-gnu-

Now change into the root directory of the source tree and clean the build area:

fakeroot debian/rules clean

Kick off a menuconfig session with script:

fakeroot debian/rules editconfigs

menuconfig insists on running once each for 32 and 64 bit builds of kernel.

Now build the kernel and associated packages. We skip checks that are likely to break because of a changed list of modules:

fakeroot debian/rules binary skipmodule=true skipabi=true

This will result in the following .deb packages being created in the level ABOVE the kernel source tree:

linux-buildinfo-5.4.0-1019-raspi_5.4.0-1019.21+g34950~20200925_arm64.deb
linux-headers-5.4.0-1019-raspi_5.4.0-1019.21+g34950~20200925_arm64.deb
linux-image-5.4.0-1019-raspi_5.4.0-1019.21+g34950~20200925_arm64.deb
linux-modules-5.4.0-1019-raspi_5.4.0-1019.21+g34950~20200925_arm64.deb
linux-raspi-headers-5.4.0-1019_5.4.0-1019.21+g34950~20200925_arm64.deb

After copying to the target, each of the relevant packages may be installed there with dpkg:

dpkg -i linux-headers-5.4.0-1019-raspi_5.4.0-1019.21+g34950~20200925_arm64.deb
dpkg -i linux-image-5.4.0-1019-raspi_5.4.0-1019.21+g34950~20200925_arm64.deb
dpkg -i linux-modules-5.4.0-1019-raspi_5.4.0-1019.21+g34950~20200925_arm64.deb
dpkg -i linux-raspi-headers-5.4.0-1019_5.4.0-1019.21+g34950~20200925_arm64.deb