I found myself wanting to run a Raspberry Pi 4B in 32-bit mode. It turns out it’s not enough to install the armhf Raspberry Pi OS image - as this runs the Pi with a 64-bit kernel but 32-bit packages:

~ $uname -a
Linux pi14 6.1.55-v8+ #1686 SMP PREEMPT Thu Oct  5 15:47:38 BST 2023 aarch64 GNU/Linux

~ $getconf LONG_BIT

~ $dpkg-architecture |grep "DEB_BUILD_ARCH="

The problem here is that the armhf OS image includes the 64-bit kernel kernel8.img and by default the firmware choses a 64-bit kernel for a Pi 4.

There’s two obvious solutions. The recommended one is to add this to /boot/config.txt:


This will force the firmware to chose a 32-bit kernel image.

The other option is to delete/rename /boot/kernel8.img so the firmware can’t find it.

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