Cowell Computer Consulting

Previously, I had written about what you can do with a soekris. I did get everything working as it should and it was pretty interesting. I'd unplug the unit and watch that it would flawlessly start up again. This is important because there's no screen hooked up to these and if the filesystem were to become dirty, login requires a null modem cable, which not everyone keeps handy.

Goals:

• can be safely unplugged at any time
• can receive commands from web or sshd

I thought that I had achieved my goals and all I had to do was put a web server on there. Lighttp seemed like the best bet, being pretty compact, but I was quickly realizing that 64MB wasn't going to be enough space to fit everything into.

What I've opted to do is have the / filesystem still load up with the kernel into memory in rw mode and have /usr mount off the card in ro mode. Lock and temp files are written to /tmp + /var under /.

The only pain in the butt about this is that if you want to make a change to the system you must connect a null modem cable and do the following.

shutdown -t now
umount /dev/wd0a
mount -rw /dev/wd0a

This isn't a major problem as there are rarely going to be changes that need to be made. I the next iteration of this project I am going to divide the card up into several partitions.

wd0a rw   /         25MB    kernel is read of this partition. Completely volatile.
wd0e ro   /usr     200MB    all our userland stuff
wd0f rw   /data     10MB    special

/data would be mounted after startup by an rc script. This is important because /data could be dirty and could impede startup of basic services. /data would also have a rc.local script on it that would be called on startup that would copy files or config, restart services etc.

I've also been working a little with Axis cameras and have noticed that they use an embedded Linux system. I think they use uClinux.