The MLO (Boot loader) and U-Boot actually load from the SD Card, and it also got all it's power from the mainboard.I don't think so. That's just the debug output from the processor. It's got as far as starting uboot, which is nice, but it hasn't got to booting anything from an SD card - it hasn't got any RAM to load a kernel into. Uboot's probably XIP (eXecute In Place) meaning it can print out that debug information just using the program counter and a few other registers.nice! so, if I understand correctly the boot-up test was the cpu board plugged in the mainboard, booting from an SD card? (so everything working minus the RAM)
So yes, the mainboard and CPU Board are working together here.