Experimental Physics and
Industrial Control System

Michael Abbott <[email protected]> · Thu, 8 Jul 2010 14:49:42 +0100 (BST)

Some while ago I spent some time putting together a set of scripts to help 
automate the process of building a complete root filesystem to target 
embedded Linux.  Of course this has been done innumerable times already, 
so I'm never sure the exercise was all that valuable, but the results have 
been very well behaved for us at Diamond.

The basic idea is to build a complete and small (3-5MB using glibc, would 
be much smaller with ulibc) root filesystem consisting of the minimal 
files required to boot and run the target system.  I use busybox for shell 
and basic utilities, and a number of other components can optionally be 
cross-compiled and installed on the target.  EPICS runs just fine in this 
environment.

The rootfs is designed to be reassembled from scratch every time any part 
of the configuration is modified: this ensures completely reproducible and 
predictable system behaviour, and is entirely practical with such a small 
system.

We have targeted the Instrumentation Technologies Libera SBC (ARM Xscale 
PXA 255) and a Toradex Colibri ARM PXA 270 as well as the embedded PowerPC 
core to be found in some Xilinx FPGAs.

The rootfs build script is easily configurable and I hope will be useful 
for other people.  Please find the rootfs system (and some wrapper scripts 
for building the associated toolchain) at:

	http://controls.diamond.ac.uk/downloads/targetOS

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System