之前只是编译Uboot，并用其刷写固件。
这里将对其使用进行新一步的研究
通过help得：
? – alias for ‘help’
bootm – boot application image from memory
cp – memory copy
erase – erase SPI FLASH memory
go – start application at address ‘addr’
help – print online help
loadb – load binary file over serial line (kermit mode)
md – memory display
mdio – Ralink PHY register R/W command !!
mm – memory modify (auto-incrementing)
nm – memory modify (constant address)
printenv- print environment variables
reset – Perform RESET of the CPU
rf – read/write rf register
saveenv – save environment variables to persistent storage
setenv – set environment variables
tftpboot- boot image via network using TFTP protocol
version – print monitor version
