开发板： S3C6410，已经安装linux，非nfs挂载时可以正常启动 ip:192.168.1.178
开发主机环境：Win7主机一台，安装了虚拟机装的是UBUNTU
通过网线直接连接,开发板ip：192.168.1.20。inet addr:192.168.1.178 Bcast:192.168.1.255 Mask:255.255.255.0
前提： 开发板与UBUNTU主机相互可以ping通，无丢包情况
# mount 192.168.1.178:/nfsboot /mnt 挂载成功
#df 可以查看到已经挂载成功
# sudo umount /mnt 取消挂载
按复开发板位键，同时在超级终端敲空格键，启动uboot
输入命令
setenv bootargs noinitrd root=/dev/nfs console=ttySAC0 init=/linuxrc nfsroot=192.168.1.178:/nfsboot ip=192.168.1.20:192.168.1.178:192.168.1.1:255.255.255.0::eth0:on fbcon=rotate:1
运行saveenv
重启开发板
#0: SMDK6400 (WM9713)
TCP cubic registered
NET: Registered protocol family 17
can: controller area network core (rev 20081130 abi 8)
NET: Registered protocol family 29
RPC: Registered udp transport module.
RPC: Registered tcp transport module.
ieee80211: 802.11 data/management/control stack, git-1.1.13
ieee80211: Copyright (C) 2004-2005 Intel Corporation <
jketreno@linux.intel.com>
VFP support v0.3: implementor 41 architecture 1 part 20 variant b rev 5
s3c2410-rtc s3c2410-rtc: setting system clock to 2011-09-20 11:16:59 UTC (1316517419)
eth0: link down
IP-Config: Complete:
device=eth0, addr=192.168.1.20, mask=255.255.255.0, gw=192.168.1.1,
host=192.168.1.20, domain=, nis-domain=(none),
bootserver=192.168.1.178, rootserver=192.168.1.178, rootpath=
Looking up port of RPC 100003/2 on 192.168.1.178
eth0: link up, 100Mbps, full-duplex, lpa 0xCDE1
Looking up port of RPC 100005/1 on 192.168.1.178
Root-NFS: Server returned error -13 while mounting /nfsboot（估计是这里的问题，网上有查说是路径错误，但是我仔细看了路径应该没错的）
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 4096 mtdblock0 (driver?)
1f01 1040384 mtdblock1 (driver?)
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(2,0)
eth0: link down
请高手们指教一下，问题可能出在哪里，如何解决。
