Step-by-step NFS-mounted Root File System

THIS TOPIC ACTIVELY BEING EDITED. IT IS NOT COMPLETE

This tutorial is for Developers

Introduction

A common technique for embedded development is to NFS-mount your root file system. This means that all files are actually on a host. The host is configured to export the filesystem. The target (odroid) mounts the filesystem at boot time and uses it as its own. All files are visible on the host.

As targets have increased in storage capacity and speed, the need for NFS-mounting root file systems will decrease. The technique is still useful when bringing up a new port or you have a lot of files that need to change together.

It is common to check in a whole root file system into a source control system for quality control.

Prerequisites

You need to be able to edit files on the odroid, or how to move them to a host and back for editing

You need to know how to build a kernel. There are many ways to do it. This tutorial walks through a native kernel build: Kernel Compiling

You need to know how to abort booting at the u-boot console. [http://odroid.us/mediawiki/index.php?title=U-boot_Topics&action=view&section=5 Abort boot at u-boot console]

You will need some patience... NFS exporting and mounting can be frustrating

Overview

We are going to:

Add some u-boot environment variables to steer the boot process

Mount the boot partition read/write

Compile a custom u-boot script to add parameters to the kernel command line

Replace the standard boot.scr with our custom one

Setup the root file system directory

Configure NFS-exports

Test the NFS server

reboot and see that we actually are running from files living on the host