I got slackwarearm to install on the Odroid U3 board, i will be installing it on the XU4 soon too. If anyone is interested a working SD card image for the U3 is available here:
http://ctrlr.org/nightly/slakarm_odroidu3.img.gz
it contains the needed u-boot/kernel (4.0) etc.
Kernel/u-boot is based on the tizen.org repositories