Yep, these days you can enjoy a good Linux mainline support for RIoTBoard, thanks to the hard work of lots of people. Here are my notes how to build latest Linux kernel for this cool board.
tar xf linux-3.17.tar.xz && cd linux-3.17
make distclean && make imx_v6_v7_defconfig && make LOADADDR=0x10008000 uImage -j4
cp arch/arm/boot/uImage ~/riotboard/
cp arch/arm/boot/dts/imx6dl-riotboard.dtb ~/riotboard/
make modules_install INSTALL_MOD_PATH=~/riotboard
Well, now ~/riotboard contains the fresh kernel, device tree and drivers, so you can copy them to your embedded target.