我在ubuntu 14.04LTS使用NFS挂载mini2440一直失败，我的步骤记录：
1，安装nfs服务 sudo apt-get install nfs-kernel-server
2,新建共享目录，在/home下解压友善的rootfs_qtopia_qt4文件系统包，改名为Mini2440-NFS，设置权限为777。
3，编辑/etc/exports文件，添加/home/camel/Mini2440-NFS *(rw,sync,no_root_squash)
4，重启NFS服务sudo /etc/init.d/nfs-kernel-server restart
5，ifconfig命令查看网络连接如图，
[url=mailto:root@camel-dynabook-SS-1700MY-106S-2]root@camel-dynabook-SS-1700MY-106S-2[/url]:~# ifconfig
eth0 Link encap:以太网 硬件地址 00:1c:7e:91:c7:aa
inet6 地址: fe80::21c:7eff:fe91:c7aa/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 跃点数:1
接收数据包:0 错误:0 丢弃:0 过载:0 帧数:0
发送数据包:224 错误:0 丢弃:0 过载:0 载波:0
碰撞:0 发送队列长度:1000
接收字节:0 (0.0 B) 发送字节:44906 (44.9 KB)
lo Link encap:本地环回
inet 地址:127.0.0.1 掩码:255.0.0.0
inet6 地址: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 跃点数:1
接收数据包:2054 错误:0 丢弃:0 过载:0 帧数:0
发送数据包:2054 错误:0 丢弃:0 过载:0 载波:0
碰撞:0 发送队列长度:0
接收字节:293895 (293.8 KB) 发送字节:293895 (293.8 KB)
wlan0 Link encap:以太网 硬件地址 00:1b:9e:fb:6b:a7
inet 地址:192.168.1.116 广播:192.168.1.255 掩码:255.255.255.0
inet6 地址: fe80::21b:9eff:fefb:6ba7/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 跃点数:1
接收数据包:740936 错误:0 丢弃:0 过载:0 帧数:0
发送数据包:442245 错误:0 丢弃:0 过载:0 载波:0
碰撞:0 发送队列长度:1000
接收字节:1094026905 (1.0 GB) 发送字节:36368663 (36.3 MB)
得主机ip为192.168.1.116
用minitools像mini2440写入命令行参数console=ttySAC0root=/dev/nfsnfsroot=192.168.1.116:/home/camel/Mini2440-NFSip=192.168.1.70:192.168.1.116:192.168.1.116:255.255.255.0:sbc2440.arm9.net:eth0:off
挂载mount -t nfs -o nolock 192.168.1.116:/home/camel/Mini2440-NFS /mnt，进入/mnt可以看到Mini2440-NFS的内容。
root@camel-dynabook-SS-1700MY-106S-2:~# mount -t nfs -o nolock 192.168.1.116:/home/camel/Mini2440-NFS /mnt
root@camel-dynabook-SS-1700MY-106S-2:~# cd /mnt
root@camel-dynabook-SS-1700MY-106S-2:/mnt# ls
bin etc lib mnt proc sbin sys usr www
dev home linuxrc opt root share tmp var
6，串口连接开发板，打开kermit,nand启动mini2440，输出错误信息如下
IP-Config: Complete:
device=eth0, addr=192.168.1.70, mask=255.255.255.0, gw=192.168.1.111,
host=sbc2440, domain=, nis-domain=arm9.net,
bootserver=192.168.1.111, rootserver=192.168.1.116, rootpath=
Looking up port of RPC 100003/2 on 192.168.1.116
eth0: link up, 100Mbps, full-duplex, lpa 0x45E1
rpcbind: server 192.168.1.116 not responding, timed out
Root-NFS: Unable to get nfsd port number from server, using default
Looking up port of RPC 100005/1 on 192.168.1.116
rpcbind: server 192.168.1.116 not responding, timed out
Root-NFS: Unable to get mountd port number from server, using default
Root-NFS: Server returned error -5 while mounting /home/camel/Mini2440-NFS
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 256 mtdblock0one_wire_status: 4
(driver?)
1f01 128 mtdblock1 (driver?)
1f02 5120 mtdblock2 (driver?)
1f03 256640 mtdblock3 (driver?)
1f04 262144 mtdblock4 (driver?)
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(2,0)
one_wire_status: 4
Backtrace:
[<c00341cc>] (dump_backtrace+0x0/0x10c) from [<c0329f3c>] (dump_stack+0x18/0x1c)
r7:c03dba08 r6:00008000 r5:c3923000 r4:c0481c90
[<c0329f24>] (dump_stack+0x0/0x1c) from [<c0329f8c>] (panic+0x4c/0x114)
one_wire_status: 4
[<c0329f40>] (panic+0x0/0x114) from [<c0008dbc>] (mount_block_root+0x174/0x228)
r3:c38583ec r2:00000000 r1:c3823f60 r0:c03db9a0
[<c0008c48>] (mount_block_root+0x0/0x228) from [<c0008f34>] (mount_root+0xc4/0xfc)
[<c0008e70>] (mount_root+0x0/0xfc) from [<c0009094>] (prepare_namespace+0x128/0x180)
r5:c002081d r4:c0481660
[<c0008f6c>] (prepare_namespace+0x0/0x180) from [<c00084b0>] (kernel_init+0xe0/0x114)
r5:c001f2e4 r4:c0481420
[<c00083d0>] (kernel_init+0x0/0x114) from [<c004bbbc>] (do_exit+0x0/0x620)
r5:00000000 r4:00000000
one_wire_status: 4
6，以前用showmount -e还能看到成功信息
root@camel-dynabook-SS-1700MY-106S-2:~# showmount -e
Export list for camel-dynabook-SS-1700MY-106S-2:
/home/camel/Mini2440-NFS *
后来因为挂载不上，我对/etc/hosts.deny，/etc/hosts.allow进行配置，后来showmount -e就失败了。
RPC: Port mapper failure - RPC: Unable to receive
希望大侠们能对过程中的错误指点一二。
