openbsd

Hacking Your First Hackathon

Submitted by tomo on June 8, 2013 - 2:13pm

Today I'll be speaking, mentoring, then judging at Keewi's Hack Day event.

Over a decade ago I joined a group of "hackers" in developing an open source ultra-secure UNIX operating system called OpenBSD. As the most secure OS in the world, it was designed to keep out hackers, as in crackers, those seeking unauthorized access to computer systems. But we were also hackers, a type of "artisanal" programmer. OpenBSD hackers are spread across the world and they gather themselves together periodically into one place to be super productive on a common goal over the course of several days. OpenBSD invented the hackathon, even coining the word itself.

I attended my first hackathon back when I was still in school, which I graduated from over 10 years ago. It was organized by our university's open source club, the only extracurricular activity I was involved in. We got permission to use one of the classrooms overnight and even got funding to buy a couple pizzas and pop. That was it. There were no corporate sponsors. There were no spectators watching us code except for our confused girlfriends. There were no headhunters or suits looking for geeks they could make use of. And there was no prize money because we were just there to see what hacks we could pull off in a night and then show each other.

Nowadays, hackathons are more and more common and are seen by corporations as something they can take advantage of.

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OpenBSD uvm_mapent_alloc: out of static map entries

Submitted by tomo on April 2, 2011 - 3:02am

Every few months, I've had remote OpenBSD servers die mysteriously, without any visible console messages, and still responding to pings, although higher level networking (http, ssh) are unresponsive. The crontab I setup to dump output from top (or systat) also stops. But before the kernel failure load was low and swap was unused.

After rebooting and checking dmesg, I see before the most recent reboot:

uvm_mapent_alloc: out of static map entries

Doing some research, it seems like it could be a problem with kmem_map fragmentation, possibly from long-running processes (like apache, which is being used more heavily now). The problem appears to have been fixed in recent releases of OpenBSD which dynamically increase kmem, but upgrading the server right now isn't feasible.

So the solution is to compile a custom kernel with an increased MAX_KMAPENT added to GENERIC config:

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About the author

Asian-American expat living in Vietnam over 3 years. I am involved in tech startups and do Drupal consulting. I choose to live in Saigon and Vietnam and I want to see the city and its people reach their true potential.

Where is Saigon?

It's not wrong to wonder where in the world Saigon is.

Saigon is the name of the city now officially known as Ho Chi Minh City. But most people who call Saigon home call their home Saigon and it's mostly tourists who I hear refer to it as Ho Chi Minh City (or Ho Chi Minh Ville for the French).

After the Vietnam/American War ended in 1975, many place names ceased to exist such as Saigon, South Vietnam, and plenty of street names.

Tu Do is now Dong Khoi, Thong Nhat is Le Duan. And Tan Son Nhut Airport is now Tan Son Nhat International Airport. Rue Paul Blanchy has been Hai Ba Trung since the 1950s.

Those who haven't seen Vietnam for decades will be confused not just by the geographical changes but the incredible amount of development and modernization that has since taken place.

Latest Technical Posts

I also post a lot of technical material unrelated to Vietnam that doesn't hit the home page. Starting from November 2015 I am only posting technical articles on my new sub-blog: TECH.saigonist.com

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