use_rpi_bootloader_on_ubuntu_rpi.sh

#!/bin/bash
echo "* Disabling any non-vmlinuz kernel lines"
echo "  in /boot/firmware/config.txt ."
sed -i -E '/(^kernel=vmlinuz)/!s/^kernel=/#kernel=/g' /boot/firmware/config.txt
echo "* Adding line to use the rpi bootloader to load the kernel"
echo "  in /boot/firmware/config.txt ."
if ! grep -qs '^kernel=vmlinuz' /boot/firmware/config.txt
        then echo "kernel=vmlinuz" >> /boot/firmware/config.txt
fi
echo "* Adding line to use the rpi bootloader to load the initrd"
echo "  in /boot/firmware/config.txt ."
if ! grep -qs '^initramfs initrd.img followkernel' /boot/firmware/config.txt
        then echo "initramfs initrd.img followkernel" >> /boot/firmware/config.txt
fi
mkdir -p /etc/kernel/postinst.d
echo "* Creating /etc/kernel/postinst.d/zzzz_rpi_kernel ."
cat <<-'EOF' > /etc/kernel/postinst.d/zzzz_rpi_kernel
	#!/bin/sh -eu
	#
	# This uncompresses the arm64 kernel so the rpi bootloader 
	# can load it.
	#
	# First exit if we aren't running an ARM64 kernel.
	#
	[ $(uname -m) != aarch64 ] && exit 0
	#
	#KERNEL_VERSION="$1"
	KERNEL_INSTALLED_PATH="$2"
	
	gunzip -c -f ${KERNEL_INSTALLED_PATH} > ${KERNEL_INSTALLED_PATH}.nogz \
	&& mv -f ${KERNEL_INSTALLED_PATH}.nogz ${KERNEL_INSTALLED_PATH}
	
	exit 0
EOF
chmod +x /etc/kernel/postinst.d/zzzz_rpi_kernel