请问nfs挂载报这样的错该如何解决？

我板子想通过nfs挂载板子自带的rootfs[img=0,1]file:///C:\Users\敏\AppData\Roaming\Tencent\Users\464044001\QQ\WinTemp\RichOle\64OCPJEI_7ENHKQ]@[@E275.jpg[/img]文件系统，步骤是按文档上来的，关于nfs在电脑上用mount命令测试是可用的，在板子上挂载却报错：
ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
IP-Config: Complete:
     device=eth0, addr=192.168.1.6, mask=255.255.255.0, gw=192.168.1.6,
     host=www, domain=, nis-domain=embedsky.com,
     bootserver=192.168.1.8, rootserver=192.168.1.8, rootpath=

***************在此处出现了错误**************************
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             128 mtdblock2  (driver?)
1f03             128 mtdblock3  (driver?)
1f04            1920 mtdblock4  (driver?)
1f05             128 mtdblock5  (driver?)
1f06            3072 mtdblock6  (driver?)
1f07            5120 mtdblock7  (driver?)
1f08         1037824 mtdblock8  (driver?)
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(2,0)
Backtrace:
[<c00181e0>] (dump_backtrace+0x0/0x10c) from [<c05f1fbc>] (dump_stack+0x18/0x1c)
r7:c074f4e8 r6:00008000 r5:c08b7810 r4:c08b7810
[<c05f1fa4>] (dump_stack+0x0/0x1c) from [<c05f2024>] (panic+0x64/0x198)
[<c05f1fc0>] (panic+0x0/0x198) from [<c0816d8c>] (mount_block_root+0x174/0x228)
r3:00000000 r2:00000000 r1:df82df58 r0:c074f598
[<c0816c18>] (mount_block_root+0x0/0x228) from [<c0816ef0>] (mount_root+0xb0/0xcc)
[<c0816e40>] (mount_root+0x0/0xcc) from [<c0817074>] (prepare_namespace+0x168/0x1c0)
r4:c08b68e0
[<c0816f0c>] (prepare_namespace+0x0/0x1c0) from [<c08162f8>] (kernel_init+0xf0/0x124)
r5:c0853bec r4:c08b6880
[<c0816208>] (kernel_init+0x0/0x124) from [<c003f564>] (do_exit+0x0/0x69c)
r5:c0816208 r4:00000000

求解，这错误是什么原因造成的？


[img]file:///C:\Users\敏\AppData\Roaming\Tencent\Users\464044001\QQ\WinTemp\RichOle\64OCPJEI_7ENHKQ]@[@E275.jpg[/img]
[img]file:///C:\Users\敏\AppData\Roaming\Tencent\Users\464044001\QQ\WinTemp\RichOle\64OCPJEI_7ENHKQ]@[@E275.jpg[/img]

[img]file:///C:\Users\敏\AppData\Roaming\Tencent\Users\464044001\QQ\WinTemp\RichOle\64OCPJEI_7ENHKQ]@[@E275.jpg[/img]

[img]file:///C:\Users\敏\AppData\Roaming\Tencent\Users\464044001\QQ\WinTemp\RichOle\64OCPJEI_7ENHKQ]@[@E275.jpg[/img]

我发邮件给天嵌，也没解决这个问题