Jetson TK1-Boot Loader Clarification

I am designing my own Jetson TK1 board.I read that there are 3 boot sources EMMC,SPI flash and USB(Recovery Mode) but i cant figure out that how would i load the bootloader on my freshly designed board…?

This doc might help:

As you can see in design guide, there are strapping for boot device option, default setting (1011) is for eMMC, 1000 is fro SPI.