But my point is that you need to have a valid boot or valid not-boot on the eMMC. In other words, you might as well have U-boot there. The danger is that if U-boot on the eMMC gets corrupted, you can't boot from SD. So alternatively, you can make the eMMC not-boot, and put U-boot on micro-sd. In that case, if the not-boot state of the eMMC gets corrupted, the same way a valid boot state could get corrupted, you still cannot boot from SD. So why not have it in the eMMC where it'll boot sooner and faster?
:wq
[ SRA accepts you ]
[ SRA accepts you ]