1、配置网络部分，主要是使能CONFIG_IP_PNP以在2中能够看到Root file system on NFS选项
Networking support 
Networking options 
TCP/IP networking
IP: kernel level autoconfiguration
[*] IP: DHCP support
[*] IP: BOOTP support

2、配置开启nfs服务
File systems --->
Network File Systems --->
<*> NFS client support 
[*] NFS client support for NFS version 3 [*] NFS client support for the NFSv3 ACL protocol extension 
[*] NFS client support for NFS version 4 (EXPERIMENTAL) 
[*] NFS client support for NFSv4.1 (DEVELOPER ONLY) 
[*] Root file system on NFS 

3、在uboot中设置如下启动参数（IP根据实际使用更改）
setenv bootargs root=/dev/nfs nfsroot=192.168.1.105:/mnt/rootfs/rootfs ip=192.168.1.88:192.168.1.105:192.168.1.1:255.255.255.0::eth0:off init=/linuxrc console=ttySAC2,115200