In Memoriam: Hans Petter William Sirevåg Selasky

20 July, 2023 by carlavilla@freebsd.org | freebsd
The FreeBSD community was saddened this month by the tragic death of
one of its most prolific contributors.  We learned that Hans Petter
Selasky passed away in a traffic accident in Lillesand, Norway on June
23, 2023 at the age of 41.  Hans was an incredibly brilliant and kind
person, and made many valuable contributions to FreeBSD.  He was
preceded in death by his father Gordon, and is survived by his mother,
Inger Elisabeth, his brothers Mark and Leif Conrad, and his nieces and
nephews Petra, David and Signe.

Hans began contributing to FreeBSD roughly 25 years ago, with fixes to
FreeBSD’s ISDN support.  He was a FreeBSD committer for nearly 15
years, and was best known for re-writing and maintaining the USB
stack.  Hans wrote the webcamd package which supports running Linux
webcam drivers in userspace on FreeBSD, and which enables those of us
using FreeBSD on the desktop to participate in modern
teleconferencing.  Most recently, he worked for Mellanox (now Nvidia)
to support their ConnectX series of high speed NICs on FreeBSD.
Hans’s work included major contributions to the kernel TLS framework,
as well as support for NIC kTLS send and receive offload in the mce(4)
driver, and many improvements to the Linux device driver compatibility
layer.

I first met Hans in 2015, in the context of his work on the mce(4)
driver for Mellanox NICs.  We worked together to make the mce(4)
driver one of highest performance NIC drivers in FreeBSD.  It was
during this time that I learned how brilliant Hans was.  He often had
ideas that sounded “crazy”, but which were actually brilliant.  One
example of this was his idea to sort incoming TCP packets using the
NIC provided RSS flow identifiers in order to present LRO with all
packets from the same TCP connection back to back.  This idea, which I
initially discounted as impractical, was crucial to Netflix being able
to meet our performance target of serving 100Gb/s of video traffic
from a single machine, and continues to save Netflix a large amount of
CPU resources.

Hans was a very kind and welcoming person.  The first time I attended
EuroBSDCon was in 2019 in Lillehammer, Norway where Hans insisted on
playing host to me.  Hans had driven across Norway from his home in
Grimstad to EuroBSDCon in Lillehammer with his father, and took me
around to see the Olympic ski jump, along with several other sites in
the town.  He then took me out to dinner, and back to the house he’d
rented with his father for an evening of great conversation.

Outside of FreeBSD, Hans’s hobbies included music and mathematics.  He
was active in his church, and contributed to its sound team.  He was a
loving and dedicated uncle to his nieces and nephews.  He loved
animals, especially his cat Pumba.

Even if you don’t use FreeBSD yourself, odds are good that Han’s work
touches on your daily life. For example, if you use a Playstation,
chances are you are using Hans’ USB stack.  If you watch Netflix, the
odds are good that the show you’re watching was delivered to you by a
ConnectX NIC running Hans’s mce(4) driver.

Hans, if you are reading this, know that you will be missed.

-- Drew Gallatin