U-Boot loader for RIoTboard

To install this bootloader on an sdcard just do :
dd if=$LOCALBASE/share/u-boot/u-boot-riotboard/u-boot.imx of=/path/to/sdcarddevice bs=1k seek=1 conv=sync

This version is patched so that:
 * API features is enabled.
 * A boot.scr (U-Boot script) that loads ubldr.bin and execute it is included

For information about running FreeBSD on IMX6 boards, see
https://wiki.freebsd.org/FreeBSD/arm/imx6