nfs-rootfs-setup-linux.txt

英培特公司ARM开发板手册,包括地址说明,WINCE,LINUX安装

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*
* Documentation/arm/ep93xx/nfs.txt
* 
* NFS configuration howto for the EDB93XX platform
*
*  Copyright (c) 2003 Cirrus Logic, Inc
*  
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The configuration described in this document will enable the EDB93XX Linux
to mount a network file system as the root file system during Linux boot.
With this configuration you don't need to load a ramdisk image to the EDB93XX
platform, or program the ramdisk image into EDB93XX flash.  But, you do need
to enable a Linux host to serve up a network file system to the EDB93XX Linux
platform. This document describes how to configure both the Linux host and
the Linux kernel for the EDB93XX target platform.
																									  
HOST SETUP:
1. Create a directory on the Linux host pc.  This directory will be exported
to the ep93xx Linux target platform as it's root file system in place of
a ramdisk image.  Set up the root file system by copying the contents of the 
ramdisk image, included with the Linux sources, to the directory created
on the Linux host. 

The ramdisk image is compressed.  To mount it we'll have to un-compress it first:

	>> gunzip ramdisk.gz

Use the following command to mount the ramdisk image (must have root privileges 
to execute this command):

	>> mount ramdisk <ramdisk mount dir> -o loop

where <ramdisk mount directory> is the directory to mount the ramdisk file system.
This directory should be different from the nfs directory created earlier in
this step.  Once the ramdisk image is mounted, copy the contents of the mounted
ramdisk to the newly created nfs directory:

	>> cp <ramdisk mount dir>/* <nfs root dir>/.

where <ramdisk mount dir> is the directory where the ramdisk image was mounted
and the <nfs root dir> is the directory created for the nfs root file system.

2. Add the directory which will be exported to the Nexus target to the /etc/exports
file.  You can use the Linux NFS Server Configuration Tool (for Red Had 9,
/usr/bin/redhat-config-nfs) to set this up or add a line to the
/etc/exports file directly.  For example, /mnt/nfs is the directory exported to
ep93xx for this example, and here's what the Linux host /etc/exports file looks like:

/mnt/nfs *(rw,no_root_squash,insecure)

To achieve the above settings in the /etc/exports file using the NFS Server
Configuration Tool, launch the tool and select the "Add" button to add a new
exported directory. From the "Basic" tab, type the directory name in the
"Directory" field, enter a "*" in the "Host(s)" field, and in the "Basic
Permissions" section, select "Read/Write". From the "General Options" tab, select
"Allow connections from ports 1024 and higher" and "Sync write operations on
request".  From the "User Access" tab, select "Treat remote root user as local root".

This is very insecure!  This will essentially give read and write permissions
to everyone. You may want to add a more secure entry to your exports file.

3. Execute the following command:
	>> /usr/sbin/exportfs -a

4. An NFS startup script can be found in the /etc/init.d directory.  To launch 
the nfsd, execute the following:
        >> /etc/init.d/nfs start

Alternatively, if an nfs startup script does not exist in /etc/init.d, launch 
nfsd with the following command:
	>> rpc.nfsd 1  

5. Verify that nfsd is running with the following command:
	>> /usr/sbin/rpcinfo -p
	
he results should look something like this:

   program vers proto   port
    100000    2   tcp    111  portmapper
    100000    2   udp    111  portmapper
    100024    1   udp    831  status
    100024    1   tcp    833  status
    100003    2   udp   2049  nfs
    100003    3   udp   2049  nfs
    100021    1   udp   1024  nlockmgr
    100021    3   udp   1024  nlockmgr
    100021    4   udp   1024  nlockmgr
    100011    1   udp    841  rquotad
    100011    2   udp    841  rquotad
    100011    1   tcp    844  rquotad
    100011    2   tcp    844  rquotad
    391002    2   tcp   1044  sgi_fam
    100005    1   udp    788  mountd
    100005    1   tcp    790  mountd
    100005    2   udp    793  mountd
    100005    2   tcp    795  mountd

At a minimum, you should see nfs, mountd and portmapper. If you have problems
setting up an nfs server on your host, take a look at this howto webpage:

	http://nfs.sourceforge.net/nfs-howto


TARGET SETUP:
1. edit the Linux kernel command line options in arch/arm/def-configs/ep93xx_nfs.
The line of code looks like this:

	CONFIG_CMDLINE="root=/dev/nfs nfsroot=<host IP>:<directory> video=ep93xxfb ip=dhcp"

Edit the nfsroot=<host IP>:<directory> options such that <host IP> is the
IP address of the Linux host which will serve the network file system,
and <directory> is the path to the directory which will be served as the
root file system to the ep93xx Linux target.

2. To build the Linux kernel for EDB93XX with NFS support here are the configuration options needed for nfs support:

Disable the following option:
	Block Devices -->
		Initial RAM disk (initrd) support

Enable the following options:
	File Systems -->
		Kernel automounter support

		Network File Systems -->
			NFS file system support
			Root File system on NFS
	
3. When shutting down Nexus with an NFS root files system, use either the halt
command or the control-alt-delete key sequence.  This forces the nfs client to
unmount the nfs file system.

For more information on how to set this up take a look at the file nfsroot.txt
in the linux Documentation directory.