A potential new contributor dropped by on IRC asking about a problem on FreeBSD. My interest was piqued since we don't support freebsd. I hope he will start getting us some patches soon! (update, 2016-06-15: Many, many patches. So many patches.)

Anyway, I was interested enough to spin up a FreeBSD (10.2) instance and get it to the point where I could work on configure and compile errors. These are my very terse notes: 

sudo pkg install git python \
    tk86 blt tclx bwidget \
    autoconf readline pkgconf \
    boost-all gcc5 pidof gettext py27-tkinter \
    boost-python-libs \
    libGL libGLU libXmu gmake

./autogen.sh
./configure --with-realtime=uspace CC=gcc5 CXX=g++5 --without-libmodbus --disable-gtk --disable-check-runtime-deps --enable-non-distributable=yes
gmake
however in an evening's work I'm still well short of getting the software to build. One thing I ran into is that clock_nanosleep, something we use thousands of times a second, isn't available on FreeBSD, despite being in POSIX 2008.1!

(and just like their branch, mine is way too green to be ready to share with anyone)