I have a RasPi 4b, I'm trying to understand how the device tree is modified so I can use the methodology eventually for a board that has a CM4 on it.

 

So from a virgin clone of the build repo:

./compile.sh BOARD=rpi4b BRANCH=edge RELEASE=bookworm BUILD_MINIMAL=yes KERNEL_CONFIGURE=no KERNEL_GIT=full

 

install image on SD card and boot the device, go through Armbian-setup. All well and good, then varify device tree used for the boot:

cat /proc/device-tree/model

gets me a:

Raspberry Pi 4 Model B Rev 1.5

 

OK so now lets modify the device tree:

./compile.sh BOARD=rpi4b BRANCH=edge RELEASE=bookworm BUILD_MINIMAL=yes KERNEL_CONFIGURE=no KERNEL_GIT=full kernel-patch

 

When the build pauses, we open another terminal and change the device tree file (note in the build log below I had modified all the CM4 device tree files):

sudo nano ./arch/arm/boot/dts/broadcom/bcm2711-rpi-4-b.dts

Only change is to modify the model line with a marker, like my initials, new line is:

 model = "Raspberry Pi 4 Model B AJW";

close editor, and hit enter to restart the build, then copy resulting patch file to:

userpatches/kernel/archive/bcm2711-6.7/0010-simple-device-tree.patch

rebuild as before, then burn new image to SD card and retest the device tree model, but no change is apparent. 

 

 

So how do you change the device tree for a RasPi 4?

 

log-build-e9849e69-98be-4710-b3be-e05a30285a44.log

other option would be to enable DT overlays, but at present those are disabled as well.