Tag Archives: Linus

Good bye Rockbox

I’m officially not taking part in anything related to Rockbox anymore. I’ve unsubscribed and I’m out.

In the fall of 2001, my friend Linus and my brother Björn had both bought the portable Archos Player, a harddrive based mp3 player and slightly underwhelmed by its firmware they decided they would have a go at trying to improve it. All three of us had been working with embedded systems for many years already and I was immediately attracted to the idea of reverse engineering this kind of device and try to improve it. It sounded like a blast to me.

In December 2001 we had the first test program actually running on the device and flashing a led. The first little step of what would become a rather big effort. We wrote a GPLed mp3 player firmware replacement, entirely from scratch without re-using any original parts. A full home-grown tiny multitasking operating system with a UI.

Fast-forwarding through history: we managed to get a really good firmware done for the early Archos players and we managed to move on to follow-up mp3 players too. After a decade or so, we supported well over 60 different mp3 player models and we played every music format known to man, we usually had better battery life than the original firmwares. We could run doom and we had a video player, a plugin system and a system full of crazy things.

We gathered large amounts of skilled and intelligent hackers from all over the world who contributed to make this possible. We had yearly meetups, or developer conferences, and we hung out on IRC every day of the week. I still hang out on our off-topic IRC channel!

Over time, smart phones emerged as the preferred devices people would use to play music while on the go. We ported Rockbox over to Android as an app, but our pixel-based UI was never really suitable for the flexible Android world and I also think that most contributors were more interested in hacking devices than writing Android apps. The app never really attracted many users or developers so while functional it never “took off”.

mp3 players are now already a thing of the past and will soon fall into the cave of forgotten old things our children will never even know or care about.

Developers and users of Rockbox have mostly moved on to other ventures. I too stopped actually contributing to the project several years ago but I was running build clients for a long while and I’ve kept being subscribed to the development mailing list. Until now. I’m now finally cutting off the last rope. Good bye Rockbox, it was fun while it lasted. I had a massive amount of great fun and I learned a lot while in the project.


A payment on a flight story

“Three beers and three chicken sandwiches, thanks” – I said, graciously handing over my VISA card to the flight stewardess to pay for everything for me and my two Haxx friends Björn and Linus. 20 something Euros. Neither of us were carrying any cash.

We were happy that we had seats in the 7th row on the way back to Stockholm since when we flew down to FOSDEM Brussels just two days earlier we were in the 18th row and by then they had ran out of sandwiches. Brussels Airlines on a direct flight.

The lady inserted the card into her handheld card-reader, messed around a while since it wouldn’t “take” at the first attempt and then she handed it to me to enter my PIN. So I did.

credit cardsMs stewardess pressed some buttons or something and then she said, “no it doesn’t work” and continued to try inserting my card in basically every variation you can (especially having the chip side turned out has to be a very clever way) while repeating to me that it doesn’t work. This is the same card I’ve used numerous times during the weekend and I used it several times at the airport less than an hour ago. I know it works.

“OK let’s say you’re right”, I sighed as I really didn’t think I nor my card were to blame but I also didn’t feel like just causing trouble. I handed her my second VISA card. “Here, try this instead then”.

“No it doesn’t work either”. This certainly wasn’t right.

Linus reached over and offered his MasterCard. Perhaps there was a VISA problem with the device but “Sorry sir, it doesn’t work” came back. We’re now at farce level. Björn joins the fun and offers a 4th card, another MasterCard.

By this time we’ve eaten most of the sandwiches and were enjoying the beers.

The lady continued to struggle and it still didn’t work. She was starting to act a bit troubled about this and I asked her if she really insisted that all our cards are broken and she admitted that she suspected the machine wasn’t working quite as it should. Then she leaned towards the male steward who was serving drinks a couple of steps away. They fiddled a bit more and then she came back to us.

“That worked, I swiped it” she said without much further explanation and returned with Björn’s card and the receipt for the purchase. I felt quite done with this by now so I didn’t ask nor pushed her why she didn’t do that earlier. I was glad it finally was fixed. So much for me paying, now Björn did it instead. Oh well, truly fascinating that they would do like this on an airline where people have to do purchases with credit cards all the time.

Then Björn looked at the receipt he got back:

Pringles and a bottle of water, 5 Euro.

It made all three of us burst out in uncontrolled laughter. It was then followed by some contemplation what it actually meant. What exactly did Björn pay for? Did he only get the wrong receipt or did he pay for it? If so, who paid for our food and drinks?

It is 2014 and we haven’t come further than this.

(Update: Björn reminded me that we did verify the last 4 digits of the card number on the receipt and it didn’t match any of our cards…)

I go Mozilla

Mozilla dinosaur head logo

In January 2014, I start working for Mozilla

I’ve worked in open source projects for some 20 years and I’ve maintained curl and libcurl for over 15 years. I’m an internet protocol geek at heart and Mozilla seems like a perfect place for me to continue to explore this interest of mine and combine it with real open source in its purest form.

I plan to use my experiences from all my years of protocol fiddling and making stuff work on different platforms against random server implementations into the networking team at Mozilla and work on improving Firefox and more.

I’m putting my current embedded Linux focus to the side and I plunge into a worldwide known company with worldwide known brands to do open source within the internet protocols I enjoy so much. I’ll be working out of my home, just outside Stockholm Sweden. Mozilla has no office in my country and I have no immediate plans of moving anywhere (with a family, kids and all established here).

I intend to bring my mindset on protocols and how to do things well into the Mozilla networking stack and world and I hope and expect that I will get inspiration and input from Mozilla and take that back and further improve curl over time. My agreement with Mozilla also gives me a perfect opportunity to increase my commitment to curl and curl development. I want to maintain and possibly increase my involvement in IETF and the httpbis work with http2 and related stuff. With one foot in Firefox and one in curl going forward, I think I may have a somewhat unique position and attitude toward especially HTTP.

I’ve not yet met another Swedish Mozillian but I know I’m not the only one located in Sweden. I guess I now have a reason to look them up and say hello when suitable.

Björn and Linus will continue to drive and run Haxx with me taking a step back into the shadows (Haxx-wise). I’ll still be part of the collective Haxx just as I was for many years before I started working full-time for Haxx in 2009. My email address, my sites etc will remain on haxx.se.

I’m looking forward to 2014!

Haxx turns 0x10

On October 17th 1997 we registered Haxx as a company. Today we’re 0x10 years old. We like hexadecimal numbers.

BirthdaycakeHaxx was founded before the first curl version was released.

It was before Google.

It was long before Firefox and Chrome and even before the Mozilla browser appeared.

Heck, a lot of things of today didn’t exist those 16 long years ago.

It was a different and in many ways simpler world back then, but I would say that we’ve manage quite good to keep with the times and we’ve progressed fine as a company and as individuals all since then.

Me, Björn and Linus are still going strong with more contacts, more customers and possibly more fun than ever.

Happy birthday to us!

Better pipelining in libcurl 7.30.0

Back in October 2006, we added support for HTTP pipelining to libcurl. The implementation was naive and simple: it basically preferred to pipeline everything on the single connection to a given host if it could. It works only with the multi interface and if you do a second request to the same host it will try to pipeline that.


Over the years the feature was bugfixed and improved slightly, which proved that at least a couple of applications actually used it – but it was never any particularly big hit among libcurl’s vast amount of features.

Related background information that gives details on some of the problems with pipelining in the wild can be found in Mark Nottingham’s Making HTTP Pipelining Usable on the Open Web internet-draft, Mozilla’s bug report “HTTP pipelining by default” and Chrome’s pipelining docs.

Now, more than six years later, Linus Nielsen Feltzing (a colleague and friend at Haxx) strikes back with a much improved and almost completely revamped HTTP pipelining support (merged into master just hours before the new-feature window closed for the pending 7.30.0 release). This time, the implementation features and provides:

  • a configurable number of connections and pipelines to each unique host name
  • a round-robin approach that favors starting new connections first, and then pipeline on existing connections once the maximum number of connections to the host is reached
  • a max-depth value that when filled makes the code not add any more requests on that connection/pipeline
  • a pipe penalization system that avoids adding new requests to pipes that are known to be receiving very large contents and thus possibly would stall subsequent requests for an extended period of time
  • a server blacklist that allows the application to specify a list of servers for which HTTP pipelining should not be attempted – real world tests has proven that some servers are too broken to be allowed to play the game

The code also adds a feature that helps out applications to do massive amount of requests in a controlled manner:

A hard maximum amount of connections, that when reached makes libcurl queue up easy handles internally until they can create a new connection or re-use a previously used one. That allows an application to for example set the limit to 50 and then add 400 handles to the multi handle but it will still only use 50 connections as a maximum so over time when requests get completed it will start new transfers on the requests that are waiting in line and thus shrinking the queue and keeping the maximum amount of connections until there’s less than 50 left to do…

Previously that kind of queuing had to be done by the application itself, but now with the much more extensive pipelining support it really isn’t as easy for an application to know when the new request can get pipelined or create a new connection so this logic is now provided by libcurl itself. It is likely going to be appreciated and used also by non-pipelining applications…

This implementation is accompanied with a bunch of new test cases for libcurl (and even a new HTTP test server for the purpose), and it has been tested in the wild for a while with libcurl as the engine in a web browser implementation (the company doing that has requested to remain anonymous). We believe it is in fairly decent state, but as this is a large step and the first release it is shipped with I expect there to be some hiccups along the way.

Two things to take note of:

  1. pipelining is only available for users of libcurl’s multi interface, and only if explicitly enabled with CURLMOPT_PIPELINING
  2. the curl command line tool does not use the multi interface and thus it will not use pipelining

Embedded Linux hacking day

eneaOn September 10th, I sent out the invite to the foss-sthlm community for an embedded hacking event just before lunch. In just four hours, the 40 available tickets had been claimed and the waiting list started to get filled up as well… I later increased the amount to 46, we had some cancellations and I handed out more tickets and we had 46 people signed up at the day of the event (I believe 3 of these didn’t show up). At the day the event started, we still had another 20 people in the waiting list with hopes of getting a spot!

(All photos in this post are scaled down versions, click the picture to see a slightly higher resolution version!)

In Enea we had found an excellent sponsor for this event. They provided the place, the food, the raspberry pis, the coffe, the tshirts, the infrastructure and everything else that had to be there to make it an awesome day.

the-roomWe started off the event at 10:00 on October 20 in the Enea offices in Kista, Stockholm Sweden. People dropped in one by one and were handed their welcome present containing a raspberry pi board, a 2GB SD card and a USB-to-serial cable to interface/power the board with. People then found their seats in the room.

There were fruit, candy, water and coffee to start off and keep the mood high. We experienced some initial wifi and internet access problems but luckily we had no less than two dedicated Enea IT support people present and they could swiftly fix the little hiccups that occurred.

coffee machines

Once everyone seemed to have landed, I welcomed everyone and just gave a short overview of what to expect from the day, where the toilets are and so on.

In order to try to please everyone who couldn’t be with us at this event, due to plans or due to simply not having got one of the attractive 40 “tickets”, Björn the cameramanEnea helped us arrange a video camera which we used during the entire day to film all talks and the contest. I can’t promise any delivery time for them but I’ll work on getting them made public as soon as possible. I’ll make a separate blog post when there’s something to see. (All talks were in Swedish!)

At 11:30 I started off the day for real by holding the first presentation. We used one of the conference rooms for this, just next to the big room where everyone say hacking. This day we had removed all tables and only had chairs in the room movie theater style and it turned out we could fit just about all attendees in the room this way. I think that was good as I think almost everyone sat down to hear and see me:

Open Source in Embedded Systems

daniel talks open source I did a rather non-technical talk about a couple of trends in the embedded operating systems market and how I see the upcoming future and then some additional numbers etc. The full presentation (with most of the text in Swedish) can be found on slideshare.

I got good questions and I think it turned out an interesting discussion on how things run and work these days.

After my talk (which I of course did longer than planned) we served lunch. Three different sallads, bread and stuff were brought out. Several people approached me to say how they appreciated the food so I must say that Enea managed really well on that account too!

Development and trends in multicore CPUs

jonas talks about CPUs
Jonas Svennebring from Freescale was up next and talked about current multicore CPU development trends and what the challenges are for the manufacturers are today. It was a very good and very technical talk and he topped it off by showing off his board with T4240 running, Freecale’s latest flagship chip that is just now about to become available for companies outside of Freescale.

T4240 from FreeescaleOn this photo on the left you see the power supply in the foreground and the ATX board with a huge fan and cooler on top of the actual T4240 chip.

T4240 is claimed to have a new world record in coremark performance, features 12 hyper-threaded ppc cores in up to 1.8GHz.

There were some good questions to Jonas and he delivered good and well thought out answers. Then people walked out in the big room again to continue getting some actual hacking done.

We then took the opportunity to hand out the very nice-looking tshirts to all attendees, again kindly done so by Enea.

The Contest

The next interruption was the contest. Designed entirely by me to allow everyone to participate, even my friends and Enea employees etc. On the photo on the right you can see I now wear the tshirt of the day.

the contest
The contest was hard. I knew it was hard as I wanted it really make it a race that was only for the ones who really get embedded linux and have their brain laid out properly!

I posted the entire contest in separate blog post, but the gist of it was that I presented 16 questions with 3 answer alternatives. Each alternative had a sequence of letters. So after 16 questions you had 16 letter sequences you had to put in the right order to get a 17th question. The first one to give a correct answer to that 17th question would win.

A whole bunch of people gave up immediately but there was a core group who really fought hard, long and bravely and in the end we got a winner. The winner had paired up so the bottle of champagne went jointly to Klas and Jonas. It was a very close call as others were within seconds of figuring it out too.

I think the competition was harder than I thought. Possibly a little too hard…

Your own code on others’ hardware

linus talksLinus from Haxx (who shouldn’t be much of a stranger to readers of this blog) then gave some insights on how he reversed engineered mp3 players for the Rockbox project. Reverse engineering is a subject that attracts many people and I believe it has some sort of magic aura around it. Again many good questions and interested people in the room.

Linus bare targets as seen during his talk On the photo on the right you can see Linus’ stripped down hardware which he explained he had ripped off all components from in order to properly hunt down how things were connected on the PCB.


We did not keep the time schedule so we had to get the coffee break in after Linus, and there were buns and so on.


Björn from Haxx then educated the room on the Yocto Project. What it is, why it is, who it is and a little about how it is designed and how it works etc.

bjorn talks on yocto

I think perhaps people started to get a little soft in their brain as we had now blasted through all but one of the talks, and as a speaker finale we had Henrik…

u-boot on Allwinner A10

Henrik Nordström did a walk-through explaining some u-boot basics and then explained what he had done for the Allwinner targets and related info.

Henrik talks u-boot
I believe the talks were kind of the glue that made people stick around. Once Henrik was done and there was no more talks planned for the day, it was obvious that it was sort of the signal for people to start calling it a day even though there was still over one hour left until the official end time (20:00).

Henriks hardware
Of course I don’t blame anyone for that. I had hardly had any time myself to sit down or do anything relaxing during the day so I was kind of exhausted myself…


I got a lot of very positive comments from people when they left the facilities with big smiles on their faces, asking for more of these sorts of events in the future.

The back of the Enea tshirtI am very happy with the overly positive response, with the massive interest from our community to come to such an event and again, Enea was an awesome sponsor for this.

Talk audienceI didn’t get anything done on the raspberry pi during this day. As a matter of fact I never even got around to booting my board, but I figure that wasn’t a top priority for me this day.

The crowd size felt really perfect for these facilities and 40 something also still keeps the spirit of familiarity and it doesn’t feel like a “big” event or so.

Will I work on making another event similar to this again? Sure. It might not happen immediately, but I don’t see why it can’t be made again under similar circumstances.


rpi accessed with tabletAll photos on this page were taken by me, Björn Stenberg, Kjell Ericson, Mats Lidell and Mia Åkerström.

Thanks to Jonas, Björn, Linus and Henrik for awesome talks.

Thanks to Enea for sponsoring this event, and Mia then in particular for being a good organizer.

Three years of Haxx

Haxx logoAt October first, another full year of work at Haxx has been spent since I last summed up the past year (my previous posts about Haxx’s first year and second year). Three years working for Haxx full-time, and it has been another great year with lots of fun, challenges and us enjoying being independent.

During this year I ended my previous engagement with that large chip company and got a new assignment for the same customer both Björn and Linus were working for at the time. It has been a big adventure for me as I dove straight into unknown territories and I’ve spent my work days since then as a product manager, making an embedded Linux distribution. In this role I’ve travelled to US, China and South Korea during the year and I’m serving as a member of an advisory board in a related organization on behalf of my customer! I recently agreed to extending this contract to at least April 2013. Partly due to this new assignment I’ve not worked very much on foss-sthlm activities recently, but after the summer I’ve really made an effort to get this back up to speed.


Later during the year, Linus changed assignment to a new customer when we signed a sort of partnership contract with a leading global embedded software company and he then continued to do a whole series of little projects for them. After the summer Linus has grabbed a couple of curl related projects, partly still in progress.

Björn stuck around at the same customer during the entire year, and he’s been working as an engineer and developer in the team that actually makes the product I am a manager for.

Haxx towelThis year we made more Haxx merchandise. Towels, stickers and jackets have now been sent out in the world to make our name more visible in a few weird corners of the universe.

We visisted FSCONS 2011 and FOSDEM 2012, two really nice conferences for FOSS fans like us and we got to meet a lot of friends and like-minded people there.

We continue to see a demand on the market for highly skilled embedded developers, including embedded Linux and open source related activities. We wouldn’t mind extending our merry team, so we decided to document a list of requirements of what to have in order to get hired by us. So far not a single person has applied…

Haxx, the second year

Last year I posted my report of what I and my fellows did at Haxx after the first year of true and real independence. As I probably mentioned before, we registered our company 1997 but it was just a side project for over a decade.Haxx logo

Now, when we’re slowly approaching two years it is time to look back and what we’ve done during the past twelve months and what we’re doing right now.

We have firmly established ourselves even more as expert developers within embedded systems. We’re over and over again being hired by the teams that themselves are hired by companies to provide services or products. During the last twelve months, we’ve written software and software designs for a huge medical equipment company, a small video equipment manufacturer, a major international telecom, a market-leading embedded systems provider and a global chip manufacturer. We’ve debugged simulation software, designed video streaming servers, done video subtitling magic, poked on Linux kernel code and we’ve done old-school 8051 and 16bit x86 assembly. I’ve also managed to do a Embedded Linux development (in user-space) training course – twice. All this, in just the past year!

Haxx was (and presented) at FSCONS in Gothenburg, we went to (and presented at) FOSDEM in Brussels and we went to the Rockbox devcon in London. We did lots of work within the foss-sthlm community.

Oh, and we’ve revamped our logo and graphical design.

Haxx consists of three full-time employed senior expert embedded systems consultants. We’ve all been in the industry for over twenty years: Daniel Stenberg, Björn Stenberg and Linus Nielsen Feltzing.

We continuously work with partners in the area to reach out to new and existing customers. As we’re very small and rather spend our time on working in our actual assignments we appreciate the help with sales and marketing. If you’re in the Stockholm area and ever end up needing devoted and skilled embedded software hackers, call us!

I’m gonna do my very best to make sure we get another great year! I’ll report back and tell you how it went.

Haxx gets Linus over to the good side

Linus Nielsen Feltzing and I founded Haxx a long time ago, so therefore it is extra fun to welcome him to join me and Björn to work full-time for our small but already now skill-packed company. Starting December this year, Linus will do all his consultancy and contract work wearing his Haxx hat and no other. Employee number three.

He comes from an employment at the same consultant company I was employed by before (and Björn was too a while ago). With this addition Haxx is now having three full-time consultants with more than 20 years of experience each within software development and embedded systems. We have a long and thorough experience in Linux and networks, in embedded and in larger systems.Haxx

Björn and I originally got to know Linus back in 1988 when we visited a “copy-party” in Alvesta Sweden. There we (the C64 demo group named Horizon) competed against the other teams in the demo competition. We won the competition with our demo “Love This Now” while the fellows in Microsystems Digital Technology (MDT) came at second place with their “Bonanza“.

MDT consisted of two persons, and one of them was Linus.

After Alvesta, Linus and Jörgen (the other MDT member) joined Horizon and we’ve known each other since. We’ve worked on the same companies since the late 90s something until the day last year when I started working full-time for Haxx.

Linus is a hardcore embedded developer, working close to hardware and the OS, writing primarily C and assembler code. He has worked a lot with various RTOSes and Linux.

Linus is also known as one of the founders of the Rockbox project together with me and Björn.