Mounting the root filesystem using NFS

If your device has a network interface, it is best to mount the root filesystem over the network during development. It gives you access to almost unlimited storage so you can add in debug tools and executables with large symbol tables. As an added bonus, updates made to the root filesystem hosted on the development machine are made available on the target immediately. You also have a copy of log files.

For this to work, your kernel has to be configured with CONFIG_ROOT_NFS. Then, you can configure Linux to do the mount at boot time by adding the following to the kernel command line:

root=/dev/nfs

Give the details of the NFS export as follows:

nfsroot=<host-ip>:<root-dir>

Configure the network interface that connects to the NFS server so that it is available at boot time, before the init program runs by using this command:

ip=<target-ip>

There is more information about NFS root mounts in the kernel source in Documentation/filesystems...