Notes:
- 921600 baud
- Debug UART is next to boot select header

Version Information
OS: #168~14.04.1-Ubuntu SMP Sat Jan 19 11:26:28 UTC 2019
U-Boot: I don't even know, 2012.04?

Toolchain Information:
arm-linux-gnueabi: from apt repos

Flashing To MMC:
dd if=u-boot.rda of=<device> seek=256