So for this new part-time job I've got, I'm working on a Soekris net4501.
FreeBSD has some surprisingly cool support for these things thanks mostly to
's work. Now that I've managed to get a slimmed down version of
freebsd built and running (7.3meg world, 2.2 meg kernel) of a pxe boot, I've
had a chance to actually play with the darned thing.
The first thing I noticed was /dev/led/error. You can do
echo 1 > /dev/led/error
and viola! The error led on the board is on. This device
supports quite the array of syntax you can throw at it. For instance, I can do
echo "f1" > /dev/led/error
and the error led will start blinking.
Read led(4) if you care to know more about the rest of the syntax it supports
(it'll even handle morse code from running /usr/games/morse -l).
I also discovered there was support for the GPIO pins on the board, too. This
is done through the same /dev/led interfaces. To enable one of the pins as a
device, you fudge around with the machdep.elan_gpio_config sysctl and you'll
end up with devices such as /dev/led/gpio5. Neato! More about the GPIO-specific
So far so good, I've got a usable shell with most tools I use (short of gcc and gdb)
in 8.7 megs.
# df -h
Filesystem Size Used Avail Capacity Mounted on
/dev/md0 19M 8.7M 8.8M 50% /
Since it's less than 10 megs, I have it mounted in memory instead of nfs. Doesn't
hurt too much, seeing as how the board has 64 megs of ram, and with everything
booted and me logged in I have 26 megs free.
Speaking of disk size, /usr/bin/host is a whopping 1.1 megs. That's quite large for
dynamically linked binary. However, I think it was statically linked against libbind
or something silly. Either way in the final product it'll go away, shaving more disk
This project has been a grand adventure into freebsd's world build system. My
whole time working on this has been me writing one makefile. The way it works
is fairly slick, I think. First, it generates a 20 meg vnode-backed filesystem,
then builds a bunch of things from /usr/src and installs them to that new
filesystem. Once this is done, I clean out some unnecessary files like library
archives (.a files), worthless things in /usr/share, etc. The kernel is handled
much in the same way, doing make buildkernel in /usr/src and then plopping a new
kernel.gz in /tftpboot.
The cool part is how libraries are built. The makefile builds all the necessary
binaries, installs them, and then uses ldd(1) to look for library dependencies.
With this list of required libraries, it builds each required library from
/usr/src and installs those. To make things easier to work with, I have two
other make targets that let me test the system in both a jail(8) and chroot(8).
This soekris board is so cool :)