Tag Archives: reverse engineering

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.

A stream of streamings

I’m a last.fm fan. I love its ability to not only stream music without needing a dedicated client installed (yes a flash application I think suits a purpose) and I think it’s ability to provide music I might also like is amazingly nice. I’m a “random it all” kind of guy when I listen to my local music collection in most situations as well. It is not specifly well suited for listening on exact the songs you want, as if you select a specific song it won’t even play the full-length version of it.

Lately there’s been a lot of buzz in Swedish tech media about spotify, which is a similar idea (at the moment still an on invitation-only thing in Sweden). They stream music, but only to a proprietary Windows or Mac client and currently they offer free listening with ads (embedded in the audio and visible in the client) or 99 SEK (== 9 Euros == 11 USD) per month. The client is highly focused on specific songs or artists and it has nothing in the way of “random artitists I generally like and similar ones”. I’m not too thrilled.

Spotify offers its service in several places, and I hear in the UK it’s not even invitation-only (which of course is useful for the more forward-thinking hacking kind of guys who thus use a UK based proxy to reach them). There’s however no sign of a Linux client. We’re forced to run their windows client with Wine.

I’ve gotten the impression that Pandora is a similar concept to play with if you happen to be based in the US. I’m in Sweden and Pandora just shows me a “We are deeply, deeply sorry to say that due to licensing constraints, we can no longer allow access to Pandora for listeners located outside of the U.S.”

The other day despotify.se showed up. A bunch of clever hackers reverse engineered the Spotify protocol and stream and offer a full unofficial open sourced ncurses/libvorbis/pulse-audio/gstreamer/expat/zlib/openssl-based player! Reading the code shows that these guys certainly had to crack some hard nuts, but the activity in their IRC channel seems fierce and the code is rather clean so I expect it to turn out to eventually become a fine player if Spotify just doesn’t decide to play hard ball with them. Unfortunately, despotify hasn’t yet been able to produce a single sound for me since it has just died on assert()s on basically any attempts I’ve tried. The interface is also a bit… strange and not the easiest to figure out. (It should be noted that the despotify client still requires you who have an actual spotify account.)

It’ll be interesting to see how Spotify, or perhaps the big media companies owning all the music rights, will act on this initiative. This client does open up abilities for new fancy features. How about ripping the stream? How about re-distributing the stream like as a proxy? And of course it being open, it does open up for adding features I want to add.

Update: just hours after I posted this, Spotify closed access to their service using the despotify client as long as you’re not a “premium” (paying) user…

Rockbox on iAudio M3

iAudio M3This player’s been out for quite some time and most certainly won’t be found anywhere to be bought as new. Still, Jens Arnold’s been working hard on this port lately and just minutes ago he mentioned that he got sound working on it – and the build table subsequently has all three kinds of the M3 build added to it.

The M3 is roughly an M5 but without any LCD on the main unit, there’s only that one on the LCD! And of course the M5 was almost an X5 but with a greyscale LCD… So it is another one of them Coldfire 5249 based targets. The LCD on the remote is 128×96 2bit greyscale,

The M3 comes with 20 or 40GB harddisk and there’s an M3L around with a larger capacity battery

How many Rockbox ports are there now? It’s hard to tell as it really depends on what level of maturity and how much functionality you require before you count it as an actual port, but the configure script in our source tree has 38 different ones mentioned. I believe some of them are not more than embryos, but there are also other initial efforts not yet added to this script.

Cowon’s spec page on the M3.

Rockbox on Meizu M6

Meizu M6In the eternal chase for new targets to port Rockbox to, the turn seems to have come to the tiny Meizu M6 player.

This 55 gram thing is slightly smaller than a credit card (width and height at least) and it boasts a 2.4″ LCD, 4GB flash and is powered by a Samsung SA58700 (ARM940T core and a CalmRISC16 DSP thing). It has an FM tuner and built-in mic for recording as well.

There’s of course the standard Rockbox forum thread,and an HW info page in the Rockbox wiki.

Other targets with the exact same SoC include the irivers E10, clix and S10. But none of those have a Rockbox port yet.