I would be glad to see FreeBSD running on NanosG20. Since I have no idea how to do that, I need to investigate. One way would be finding a posibility to run u-boot for AT91SAM9G20 out of the NanosG20 2nd Stage Bootloader (stripped linux kernel). But another solution does exist:
It is a transplantation of PortuxG20 u-boot into NanosG20.
If this will work, next step would be flashing AT91SAM9G20 u-boot with FreeBSD booting support. And last but not least a working AT91SAM9G20 kernel must be available.
Comparison of linux and bsd kernel startup sequence:
BSD kernel structure: