Cross-compiling a kernel for the Odroid XU4 on Debian

These are notes from my trying experience bringing up a recent kernel on an Odroid XU4 running Debian Wheezy.

You’ll need a compiler toolchain on the build machine,

sudo apt-get install build-essential kernel-package u-boot-tools

Grab the configuration from here and place it in the kernel tree as .config. Now build the kernel,

export ARCH=arm
export DEB_HOST_ARCH=armhf
export CONCURRENCY_LEVEL=6
fakeroot make-kpkg --arch=arm --cross-compile arm-linux-gnueabihf- --initrd kernel_image kernel_headers

Now copy the resulting .deb to the target and install it,

$ scp ben-server.local:linux-image-4.4.0-rc2... .
$ scp ben-server.local:linux-2.6/arch/arm/boot/dts/exynos5422-odroidxu4.dtb .
$ sudo mv exynos5422-odroidxu4.dtb /boot/exynos5422-odroidxu4-4.4.0-rc2+.dtb
$ sudo dpkg -i linux-image-4.4.0-rc2+_4.4.0-rc2+-10.00.Custom_armhf.deb

Unfortunately the post-install hooks included in Odroid’s Debian distribution are a bit of a disaster. Ultimately I found it necessary to hack /etc/kernel/postinst.d/odroid-boothelper, replacing the cp lines responsible for moving the kernel image to /boot (which isn’t necessary with kernel-package-generated packages) with,

if [ ! -f /boot/${zimage} ]; then
    cp -f /lib/modules/${version}/boot/${zimage} /boot
elif [ ! -d /lib/modules/${version} -o ! -f /lib/modules/${version}/boot/${zimage} ]; then
    cp -f /boot/${zimage} /lib/modules/${version}/boot
fi
if [ ! -f /boot/${fdtbin} ]; then
    cp -f /lib/modules/${version}/boot/${fdtbin} /boot
fi

Sadly even this wasn’t enough and my patience was running thin. I just ran the script without bash -e to ensure it ran to completion,

bash -x /etc/kernel/postinst.d/odroid-boothelper 4.4.0-rc2+ /boot/vmlinuz-4.4.0-rc2+

Rebooting, I had a new kernel.