怎么把uImage加载后启动的DHCP，获取IP地址给关闭呢？

bootargs 你那里是设置为 ip=dhcp么

DM81xx_DVR_RDK_Install_Guide.pdf 里有讲的，
Use the following steps to setup the boot arguments
i. bootargs
a. For static IP
UBOOT# setenv bootargs 'mem=256M console=ttyO2,115200n8 root=/dev/nfs
rw nfsroot=192.168.1.151:/home/work/netra/dvr/rfs
ip=$[ipaddr]:$[serverip]:$[gatewayip]:$[netmask]::eth0:off
vram=20M notifyk.vpssm3_sva=0xBEE00000'
b. For DHCP based IP
UBOOT# setenv bootargs 'mem=256M console=ttyO2,115200n8 root=/dev/nfs
rw nfsroot=192.168.1.151:/home/work/netra/dvr/rfs ip=dhcp
vram=20M notifyk.vpssm3_sva=0xBEE00000