一、参考例子：
uboot-2010.06
二、uboot/include/configs/board_name.h
增加#define CONFIG_CMD_USR
三、uboot/common/Makefile
增加COBJS-$(CONFIG_CMD_USR) +=cmd_usr.o
四、uboot/common/
增加cmd_usr.c
五、cmd_usr.c书写格式
1 #include <common.h> 2 #include <command.h> 3 4 int do_cmdusr(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]) 5 { 6 //自己实现的功能：例如tftp等下载、数据校验 7 } 8 9 U_BOOT_CMD( 10 cmdusr, 3, 0, do_cmdusr, 11 "cmdusr- user cmd ", 12 " - this is cmd, Contains the following steps: " 13 " - 1... " 14 " - 2... " 15 " - 3... " 16 " - 4... " 17 );