硬件平台是TI的DM816X/AM389X开发板，SD卡启动后，在Uboot下，通过TFTP可以下载内核到内存并运行，但是不能通过NFS挂接根文件系统，bootargs=noinitrd root=/dev/nfs nfsroot=172.16.114.24:/nfsdir/xxb/rootfs ip=172.16.114.180:172.16.114.24:172.16.114.1:255.255.255.0::eth0 off' 内核通过TFTP下载到内存后通过bootm命令启动内核，故障信息如下：
VFS: Unable to mount root fs via NFS, trying floppy.
VFS: Cannot open root device "nfs" or unknown-block(2,0)
Please append a correct "root=" boot option; here are the available partitions:
1f00 128 mtdblock0 (driver?)
1f01 128 mtdblock1 (driver?)
1f02 512 mtdblock2 (driver?)
1f03 2048 mtdblock3 (driver?)
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(2,0)
请问可能是什么原因？NFS主机端自己可以挂载自己，kernel配置也检查了
