Commands are added to U-Boot by creating a new command structure. This is done by first including command.h, then using the U_BOOT_CMD() macro to fill in a cmd_tbl_t struct. U_BOOT_CMD(name,maxargs,repeatable,command,"usage","help") name: is the name of the commad. THIS IS NOT a string. maxargs: the maximum number of arguments this function takes repeatable: either 0 or 1 to indicate if autorepeat is allowed command: Function pointer (*cmd)(struct cmd_tbl_s *, int, int, char *[]); usage: Short description. This is a string help: Long description. This is a string **** Behind the scene ****** The structure created is named with a special prefix (__u_boot_cmd_) and placed by the linker in a special section. This makes it possible for the final link to extract all commands compiled into any object code and construct a static array so the command can be found in an array starting at __u_boot_cmd_start. If a new board is defined do not forget to define the command section by writing in u-boot.lds ($(TOPDIR)/board/boardname/u-boot.lds) these 3 lines: __u_boot_cmd_start = .; .u_boot_cmd : { *(.u_boot_cmd) } __u_boot_cmd_end = .;