I disabled the initialization of the vector interrupt tables in
davinci.c and then I can use u-boot commands like these
load and start ubl
dhcp; set serverip 192.168.0.88; tftp ubl_sysmobts_v2.elf; bootelf
manipulate bits. Flip a 1 to a 0:
nand read.raw 0x85000000 0x00080000 1
mm.b 0x85000000
nand write.raw 0x85000000 0x00080000 1