One of the HPC clusters we have at work has a mixed set of nodes: a few of them have InfiniBand interfaces and the others don’t. A few weeks ago we were requested to install the SoftiWARP kernel module on those nodes that lack the InfiniBand interface. We had already tried to build the module from source and it worked well, but now the challenge was to install it as a Debian package with DKMS, so it would be built for all installed kernel versions on each node.

We use Puppet to manage cluster node configuration, so you may wonder why not using Puppet instead. Well, for one we’re talking about installing the source of a kernel module, with no configuration at all. But there’s also the fact that Puppet delegates to package providers the management of software, which know much better how to deal with software upgrades. Lastly, there’s the challenge of learning something new: though I had previous knowlegde of DKMS, I had no idea on how to make a Debian package out of it.

Fortunately, I found Evgeny Golov‘s DKMS playground on Debian wiki. With those tips and my recently updated experience on packaging Perl modules for Debian, I was confident enough to try my first DKMS Debian package. Actually, it came out quite easy: I just had to adapt debian/rules a bit to accommodate modern debhelper best practices:

#!/usr/bin/make -f
pdkms:=siw-dkms
sname:=siw
sversion:=$(shell dpkg-parsechangelog|grep "^Version:"|cut -d" " -f2|rev|cut -d- -f2-|rev|cut -d':' -f2)
 
%:
    dh $@
 
override_dh_auto_install:
    dh_installdirs -p$(pdkms)  usr/src/$(sname)-$(sversion)
    cp -a *.txt Makefile *.c *.h debian/$(pdkms)/usr/src/$(sname)-$(sversion)
    sed "s/__VERSION__/$(sversion)/g" debian/dkms.conf.in > debian/$(pdkms)/usr/src/$(sname)-$(sversion)/dkms.conf

Funny enough, I spend more time filling the details on debian/copyright and debian/control files than actually setting up DKMS, so big kudos to Evgeni!

Take a look at the full debian packaging for further details. You may notice that this package has a dependency on libsiw-dev (SoftiWARP userland library), which I had to package first and was a bit trickier. More on that next time.