User Guide

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Root File System Types

CHAPTER 8

The following describes the different possibilities which can be used as root file system.

The type of rootfs must be passed as an argument to kernel by means of the bootargs

environment variable of U-Boot.

NFSROOT

The rootfs may be in a different computer on the network and not within the target. This

can be useful if, for example, a RAM disk is too small to include all the necessary files, or

allow rapid turnaround during testing and development.

An NFS root allows quick kernel downloads, helps ensure file system integrity (since the

server is basically impervious to crashes by the client), and provides virtually infinite

storage.

During development it feel free to use an NFS directory as root file system. This avoids

unnecessary flash erases, which on a power failure will result in the need to re-program

the kernel into flash. It also increases the lifetime of the module because the flash has a

limited number of erase cycles. Initialization scripts may be quickly modified since a

failure will not result in an unusable system. Initialization scripts can be fixed on the host

then reset the target.

The root file system can be installed to "/exports/BOOTDIR" issuing this command in the

project directory

To test the new image run the following command at the U-Boot prompt in your target:

$ make install-nfsroot