Archive for the ‘Development’ Category

My home setup

Monday, August 25th, 2014

I work in my home office which is upstairs in my house, perhaps 20 steps from my kitchen and the coffee refill. I have a largish desk with room for a number of computers. The photo below shows the three meter beauty. My two kids have their two machines on the left side while I use the right side of it for my desktop and laptop.

Daniel's home office

Many computers

The kids use my old desktop computer with a 20″ Dell screen and my old 15.6″ dual-core Asus laptop. My wife has her laptop downstairs and we have a permanent computer installed underneath the TV for media (an Asus VivoPC).

My desktop computer

I’m primarily developing C and C++ code and I’m frequently compiling rather large projects – repeatedly. I use a desktop machine for my ordinary development, equipped with a fairly powerful 3.5GHz quad-core Core-I7 CPU, I have my OS, my home dir and all source code put on an SSD. I have a larger HDD for larger and slower content. With ccache and friends, this baby can build Firefox really fast. I put my machine together from parts myself as I couldn’t find a suitable one focused on horse power but yet a “normal” 2D graphics card that works Fractal Designfine with Linux. I use a Radeon HD 5450 based ASUS card, which works fine with fully open source drivers.

I have two basic 24 inch LCD monitors (Benq and Dell) both using 1920×1200 resolution. I like having lots of windows up, nothing runs full-screen. I use KDE as desktop and I edit everything in Emacs. Firefox is my primary browser. I don’t shut down this machine, it runs a few simple servers for private purposes.

My machines (and my kids’) all run Debian Linux, typically of the unstable flavor allowing me to get new code reasonably fast.

Func KB-460 keyboardMy desktop keyboard is a Func KB-460, mechanical keyboard with some funky extra candy such as red backlight and two USB ports. Both my keyboard and my mouse are wired, not wireless, to take away the need for batteries or recharging etc in this environment. My mouse is a basic and old Logitech MX 310.

I have a crufty old USB headset with a mic, that works fine for hangouts and listening to music when the rest of the family is home. I have Logitech webcam thing sitting on the screen too, but I hardly ever use it for anything.

When on the move

I need to sometimes move around and work from other places. Going to conferences or even our regular Mozilla work weeks. Hence I also have a laptop that is powerful enough to build Firefox is a sane amount of time. I have Lenovo Thinkpad w540a Lenovo Thinkpad W540 with a 2.7GHz quad-core Core-I7, 16GB of RAM and 512GB of SSD. It has the most annoying touch pad on it. I don’t’ like that it doesn’t have the explicit buttons so for example both-clicking (to simulate a middle-click) like when pasting text in X11 is virtually impossible.

On this machine I also run a VM with win7 installed and associated development environment so I can build and debug Firefox for Windows on it.

I have a second portable. A small and lightweight netbook, an Eeepc S101, 10.1″ that I’ve been using when I go and just do presentations at places but recently I’ve started to simply use my primary laptop even for those occasions – primarily because it is too slow to do anything else on.

I do video conferences a couple of times a week and we use Vidyo for that. Its Linux client is shaky to say the least, so I tend to use my Nexus 7 tablet for it since the Vidyo app at least works decently on that. It also allows me to quite easily change location when it turns necessary, which it sometimes does since my meetings tend to occur in the evenings and then there’s also varying amounts of “family activities” going on!

Backup

For backup, I have a Synology NAS equipped with 2TB of disk in a RAIDSynology DS211j stashed downstairs, on the wired in-house gigabit ethernet. I run an rsync job every night that syncs the important stuff to the NAS and I run a second rsync that also mirrors relevant data over to a friends house just in case something terribly bad would go down. My NAS backup has already saved me really good at least once.

Printer

HP Officejet 8500ANext to the NAS downstairs is the house printer, also attached to the gigabit even if it has a wifi interface of its own. I just like increasing reliability to have the “fixed services” in the house on wired network.

The printer also has scanning capability which actually has come handy several times. The thing works nicely from my Linux machines as well as my wife’s windows laptop.

Internet

fiber cableI have fiber going directly into my house. It is still “just” a 100/100 connection in the other end of the fiber since at the time I installed this they didn’t yet have equipment to deliver beyond 100 megabit in my area. I’m sure I’ll upgrade this to something more impressive in the future but this is a pretty snappy connection already. I also have just a few milliseconds latency to my primary servers.

Having the fast uplink is perfect for doing good remote backups.

Router  and wifi

dlink DIR 635I have a lowly D-Link DIR 635 router and wifi access point providing wifi for the 2.4GHz and 5GHz bands and gigabit speed on the wired side. It was dead cheap it just works. It NATs my traffic and port forwards some ports through to my desktop machine.

The router itself can also update the dyndns info which ultimately allows me to use a fixed name to my home machine even without a fixed ip.

Frequent Wifi users in the household include my wife’s laptop, the TV computer and all our phones and tablets.

Telephony

Ping Communication Voice Catcher 201EWhen I installed the fiber I gave up the copper connection to my home and since then I use IP telephony for the “land line”. Basically a little box that translates IP to old phone tech and I keep using my old DECT phone. We basically only have our parents that still call this number and it has been useful to have the kids use this for outgoing calls up until they’ve gotten their own mobile phones to use.

It doesn’t cost very much, but the usage is dropping over time so I guess we’ll just give it up one of these days.

Mobile phones and tablets

I have a Nexus 5 as my daily phone. I also have a Nexus 7 and Nexus 10 that tend to be used by the kids mostly.

I have two Firefox OS devices for development/work.

I’m with Firefox OS!

Wednesday, August 13th, 2014

Tablet

I have received a Firefox OS tablet as part of a development program. My plan is to use this device to try out stuff I work on and see how it behaves on Firefox OS “for real” instead of just in emulators or on other systems. While Firefox OS is a product of my employer Mozilla, I personally don’t work particularly much with Firefox OS specifically. I work on networking in general for Firefox, and large chunks of the networking stack is used in both the ordinary Firefox browser like on desktops as well as in Firefox OS. I hope to polish and improve networking on Firefox OS too over time.

Firefox OS tablet

Phone

The primary development device for Firefox OS is right now apparently the Flame phone, and I have one of these too now in my possession. I took a few photos when I unpacked it and crammed them into the same image, click it for higher res:

Flame - Firefox OS phone

A brief explanation of Firefox OS

Firefox OS is an Android kernel (including drivers etc) and a bionic libc – simply the libc that Android uses. Linux-wise and slightly simplified, it runs a single application full-screen: Firefox, which then can run individual Firefox-apps that appears as apps on the phone. This means that the underlying fundamentals are shared with Android, while the layers over that are Firefox and then a world of HTML and javascript. Thus most of the network stack used for Firefox – that I work with – the http, ftp, dns, cookies and so forth is shared between Firefox for desktop and Firefox for Android and Firefox OS.

Firefox OS is made to use a small footprint to allow cheaper smartphones than Android itself can. Hence it is targeted to developing nations and continents.

Both my devices came with Firefox OS version 1.3 pre-installed.

The phone

The specs: Qualcomm Snapdragon 1.2GHZ dual-core processor, 4.5-inch 854×480 pixel screen, five-megapixel rear camera with auto-focus and flash, two-megapixel front-facing camera. Dual-SIM 3G, 8GB of onboard memory with a microSD slot, and a 1800 mAh capacity battery.

The Flame phone should be snappy enough although at times it seems to take a moment too long to populate a newly shown screen with icons etc. The screen surface is somehow not as smooth as my Nexus devices (we have the 4,5,7,10 nexuses in the house), leaving me with a constant feeling the screen isn’t cleaned.

Its dual-sim support is something that seems ideal for traveling etc to be able to use my home sim for incoming calls but use a local sim for data and outgoing calls… I’ve never had a phone featuring that before. I’ve purchased a prepaid SIM-card to use with this phone as my secondary device.

Some Good

I like the feel of the tablet. It feels like a solid and sturdy 10″ tablet, just like it should. I think the design language of Firefox OS for a newbie such as myself is pleasing and good-looking. The quad-core 1GHz thing is certainly fast enough CPU-wise to eat most of what you can throw at it.

These are really good devices to do web browsing on as the browser is a highly capable and fast browser.

Mapping: while of course there’s Google maps app, using the openstreetmap map is great on the device and Google maps in the browser is also a perfectly decent way to view maps. Using openstreetmap also of course has the added bonus that it feels great to see your own edits in your own neck of the woods!

I really appreciate that Mozilla pushes for new, more and better standardized APIs to enable all of this to get done in web applications. To me, this is one of the major benefits with Firefox OS. It benefits all of us who use the web.

Some Bad

Firefox OS feels highly US-centric (which greatly surprised me, seeing the primary markets for Firefox OS are certainly not in the US). As a Swede, I of course want my calendar to show Monday as the first day of the week. No can do. I want my digital clock to show me the time using 24 hour format (the am/pm scheme only confuses me). No can do. Tiny teeny details in the grand scheme of things, yes, but annoying. Possibly I’m just stupid and didn’t find how to switch these settings, but I did look for them on both my devices.

The actual Firefox OS system feels like a scaled-down Android where all apps are simpler and less fancy than Android. There’s a Facebook “app” for it that shows Facebook looking much crappier than it usually does in a browser or in the Android app – although on the phone it looked much better than on the tablet for some reason that I don’t understand.

I managed to get the device to sync my contacts from Google (even with my google 2-factor auth activated) but trying to sync my Facebook contacts just gave me a very strange error window in spite of repeated attempts, but again that worked on my phone!

I really miss a proper back button! Without it, we end up in this handicapped iphone-like world where each app has to provide a back button in its own UI or I have to hit the home button – which doesn’t just go back one step.

The tablet supports a gesture, pull up from the button of the screen, to get to the home screen while the phone doesn’t support that but instead has a dedicated home button which if pressed a long time shows up cards with all currently running apps. I’m not even sure how to do that latter operation on the tablet as it doesn’t’ have a home button.

The gmail web interface and experience is not very good on either of the devices.

Building Firefox OS

I’ve only just started this venture and dipped my toes in that water. All code is there in the open and you build it all with open tools. I might get back on this topic later if I get the urge to ventilate something from it… :-) I didn’t find any proper device specific setup for the tablet, but maybe I just don’t know its proper code word and I’ve only given it a quick glance so far. I’ll do my first builds and installs for the phone. Any day now!

More

My seven year old son immediately found at least one game on my dev phone (he actually found the market and downloaded it all by himself the first time he tried the device) that he really likes and now he wants to borrow this from time to time to play that game – in competition with the android phones and tablets we have here already. A pretty good sign I’d say.

Firefox OS is already a complete and competent phone operating system and app ecosystem. If you’re not coming from Android or Iphone it is a step up from everything else. If you do come from Android or Iphone I think you have to accept that this is meant for the lower end spectrum of smart-phones.

I think the smart-phone world can use more competition and Firefox OS brings exactly that.

firefox-os-bootscreen

Me in numbers, today

Thursday, July 31st, 2014

Number of followers on twitter: 1,302

Number of commits during the last 365 days at github: 686

Number of publicly visible open source commits counted by openhub: 36,769

Number of questions I’ve answered on stackoverflow: 403

Number of connections on LinkedIn: 608

Number of days I’ve committed something in the curl project: 2,869

Number of commits by me, merged into Mozilla Firefox: 9

Number of blog posts on daniel.haxx.se, including this: 734

Number of friends on Facebook: 150

Number of open source projects I’ve contributed to, openhub again: 35

Number of followers on Google+: 557

Number of tweets: 5,491

Number of mails sent to curl mailing lists: 21,989

TOTAL life achievement: 71,602

Crashed and recovered in no time

Wednesday, May 28th, 2014

Working from home, even writing software from home, my computer setup is pretty crucial for a productive work day.

Yesterday morning after I had sat down with my coffee and started to work on my latest patch iteration I noticed that some disk operations seemed to be very slow. I looked around and then suddenly an ‘ls’ of a directory returned an error!

I checked the system logs and I saw them filling up with error messages identifying problems with a hard drive. Very quickly I identified the drive as the bigger one (I have one SSD and one much larger HDD). Luckily, that’s the one I mostly store document, pictures and videos on and I backup that thing every night. This disk is not very old and I’ve never experienced this sort of disk crash before, not even with disks that I’ve used for many years more than I’ve used this…

boomI ripped the thing out, booted up again and I could still work since my source code and OS are on the SSD. I ordered a new one at once. Phew.

Tuesday morning I noticed that for some unexplainable reason I had my /var partition on the dead drive (and not backed up). That turned out to be a bit inconvenient since now my Debian Linux had no idea which packages I had installed and apt-get and dpkg were all crippled to death.

I did some googling and as my laptop is also a Debian sid install I managed to restore it pretty swiftly by copying over data from there. At least it (the /var contents) is now mostly back to where it was before.

On Tuesday midday, some 26 hours after I ripped out the disk, my doorbell bing-bonged and the delivery guy handed me a box with a new and shiny 3 TB drive. A couple of hours ago I inserted it, portioned it, read back a couple of hundred gigabytes of backup, put back the backup job in cron again and … yeah, I think I’m basically back to where I was before it went south.

All in all: saved by the backup. Not many tears. Phew this time.

My first Mozilla week

Friday, January 17th, 2014

Working from home

I get up in the morning, shave, eat breakfast and make sure all family members get off as they should. Most days I walk my son to school (some 800 meters) and then back again. When they’re all gone, the house is quiet and then me and my cup of coffee go upstairs and my work day begins.

Systems and accounts

I have spent time this week to setup accounts and sign up for various lists and services. Created profiles, uploaded pictures, confirmed passwords. I’ve submitted stuff and I’ve signed things. There’s quite a lot of systems in use.

My colleagues

I’ve met a few. The Necko team isn’t very big but the entire company is huge and there are just so many people and names. I haven’t yet had any pressing reason to meet a lot of people nor learn a lot of names. I feel like I’m starting out this really slowly and gradually.

Code base

Firefox is a large chunk of code. It takes some 20 minutes to rebuild on my 3.5GHz quad-core Core-i7 with SSD. I try to pull code and rebuild every morning now so that I can dogfood and live on the edge. I also have a bunch of local patches now, some of them which I want to have stewing in my own browser for a while so that I know they at least don’t have any major negative impact!

Figuring out the threading, XPCOM, the JavaScript stuff and everything is a massive task. I really cannot claim to have done more than just scratched the surface so far, but at least I am scratching and I’ve “etagged” the whole lot and I’ve spent some time reading and reviewing code. Attaching a gdb to a running Firefox and checking out behavior and how it looks has also helped.

Netwerk code size

“Netwerk” is the directory name of the source tree where most of the network code is located. It is actually not so ridiculously large as one could fear. Counting only C++ and header files, it sums up to about 220K lines of code. Of course not everything interesting is in this tree, but still. Not mindbogglingly large.

Video conferencing

I’ll admit I’ve not participated in this sort of large scale video conferences before this. Wiith Vidyo and all the different people and offices signed up at once – it is a quite impressive setup actually. My only annoyance so far is that I didn’t get the sound for Vidyo to work for me in Linux with my headphones. The other end could hear me but I couldn’t hear them! I had to defer to using Vidyo on a windows laptop instead.

Doing the video conferencing on a laptop instead of on my desktop machine has its advantages when I do them during the evenings when the rest of the family is at home since then I can move my machine somewhere and sit down somewhere where they won’t disturb me and I won’t disturb them.

Bugzilla

The bug tracker is really in the center for this project, or at least for how I view it and work with it right now. During my first week I’ve so far filed two bug reports and I’ve submitted a suggested patch for a third bug. One of my bugs (Bug 959100 – ParseChunkRemaining doesn’t detect chunk size overflow) has been reviewed fine and is now hopefully about to be committed.

I’ve requested commit access (#961018) as a “level 1″ and I’ve signed the committer’s agreement. Level 1 is entry level and only lets me push to the Try server but still, I fully accept that there’s a process to follow and I’m in no hurry. I’ll get to level 3 soon enough I’m sure.

Mercurial

What can I say. After having used it a bit this week without any particularly fancy operations, I prefer git so much more. Of course I’m also much more used to git, but I find that for a lot of the stuff where both have similar concepts I prefer to git way. Oh well, its just a tool. I’ll get around. Possibly I’ll try out the git mirror soon and see if that provides a more convenient environment for me.

curl

What impact did all this new protocol and network code stuff during my work days have on my curl activities?

I got inspired to fix both the chunked encoding parser and the cookie parser’s handling of max-age in libcurl.

What didn’t happen

I feel behind in the implementing-http2 department. I didn’t get my new work laptop yet.

Next weekDaniel's work place

More of the same, land more patches and figure out more code. Grab more smallish bugs others have filed and work on fixing them as more practice.

Also, there’s a HTTPbis meeting in Zürich on Wednesday to Friday that I won’t go to (I’ll spare you the explanation why) but I’ll try to participate remotely.

Parallel Spaghetti – decoded

Thursday, November 28th, 2013

Here’s the decoding procedure for the Parallel Spaghetti Decode challenge.

Step 1, the answers to all the questions. You will notice that I did have some fun in D6 and E2, but since they were boxes that weren’t on the right track anyway I thought you’d still enjoy them.

Step 2, let me illustrate how the above answers will take you through the maze. The correct path is made up out of yellow boxes and the correct answers are shown with red arrows leading forward. Click it for full resolution version.

The parallel spaghetti challenge correct track shown

Step 3, those different colors in the “Word” column give you the words used for the two questions. If you rearrange them, the two questions become:

which tr command line option specifies delete characters

and

what curl command line option specifies POST requests

So, it took about 14 minutes at our event for Oscar Andersson to bring the correct answer to me:

-d

Always have everything proven to work

Wednesday, November 27th, 2013

… the slides from my talk today at Techdays by Init in Stockholm:

Always have everything proven to work from Daniel Stenberg

source code survival rate

Tuesday, November 5th, 2013

The curl project has its roots in the late 1996, but we haven’t kept track of all of the early code history. We imported our code to Sourceforge late 1999 and that’s how far back we can see in our current git repository. The exact date is “Wed Dec 29 14:20:26 UTC 1999″. So, almost 14 years of development.

Warning: this blog post contains more useless info and graphs than many mortals can handle. Be aware!

How much old code remain in the current source tree? Or perhaps put differently: how is the refresh rate of the code? We fix bugs, we change things, we add features. Surely we’ll slowly over time rewrite the old code and replace it with new more shiny and better working code? I decided to check this. Here’s what I found!

The tools

We have all code in git. ‘git blame’ is the primary tool I used as it lists all lines of all source code and tells us when it was added. I did some additional perl scripting around it.

The code

I decided to check all code in the src/ and lib/ directories in the curl and libcurl source tree. The source code is used to create both the curl tool and the libcurl library and back in 1999 there was no libcurl like today so we do get a slightly better coverage of history this way.

In total this sums up to some 112000 lines in the current .c and .h files.

To count the total amount of commits done to those specific files through history I ran:

git log --oneline src/*.[ch] lib/*.[ch] | wc -l

6047 commits in total. (if I don’t specify the files and count all commits in the repo it ends up at 16954)

git stats

We run gitstats on the curl repo every day so you can go there for some more and current stats. Right now it tells us that average number of commits is 4.7 per active day (that means days when actually something was committed), or 3.4 per all days over the entire time. There was git activity 3576 days in total. By 224 authors.

Surviving commits

How much of the code would you think still remains that were present already that December day 1999?

How much of the code in the current code base would you think was written the last few years?

Commit vs Author vs Date

I wanted to see how much old code that exists, or perhaps how the age of the code is represented in the current code base. I decided to therefore base my logic on the author time that git tracks. It is basically the time when the author of a change commits it to his/her local tree as then the change can be applied later on by a committer that can be someone else, but the author time remains the same. Sometimes a committer commits multiple patches at once, possibly at a much later time etc so I figured the author time would be a better time stamp. I also decided to track the date instead of just the commit hash so that I can sort the changes properly and also make interesting graphs that are based on that time. I use the time with a second precision so changes done a second apart will be recorded as two separate changes while two commits done with the same author time stamp will be counted as the same time.

I had my script run ‘git blame –line-porcelain’ for all files and had my script sum up all changes done on the same time.

Some totals

The code base contains changes written at 4147 different times. Converted to UTC times, they happened on 2076 unique days. On 167 unique months. That’s every month since the beginning.

We’re talking about 312 files.

Number of lines changed over time

A graph with changes over time. The Y axis is number of lines that were changed on that particular time. (click for higher res)

Lines changed over time

Ok you object, that doesn’t look very appealing. So here’s the same data but with all the changes accumulated over time.

accumulated

Do you think the same as I do? Isn’t it strangely linear? It seems that the number of added lines that remain in the code today is virtually the same over time! But fair enough, the changes in the X axis are not distributed according to the time/date they represent so we shouldn’t be fooled by the time, but certainly we can see that changes in general only bring in a certain amount of surviving modified lines.

Another way to count the changes is then to check all the ~4000 change times of the present code, and see how many days between them there are:

delta

Ah, now finally we’re seeing something. Older code that is still present clearly was made with longer periods in between the changes that have lasted. It makes perfect sense to me, since the many years of development probably have later overwritten a lot of code that was written in between.

Also, it is clearly that among the more recent changes that have survived they were often done on the same day or just a few days away from another lasting change.

Grouped on date ranges

The number of modified lines split up on the individual year the change came in.

year

Interesting! The general trend is clear and not surprising. Two years stand out from the trend, 2004 and 2011. I have not yet investigated what particular larger changes that were made those years that have survived. The bump for 1999 is simply the original import and most of those lines are preprocessor lines like #ifdef and #include or just opening and closing braces { and }.

Splitting up the number of surviving lines on the specific year+month they were added:

month

This helps us analyze the previous chart. As we can see, the rather tall bars from 2004 and 2011 are actually several months wide and explains the bumps in the year-chart. Clearly we made some larger effort on those periods that were good enough to still remain in the code.

Correlate to added or removed lines?

So, can we perhaps see if some years’ more activity in number of added or removed source lines can be tracked back to explain the number of surviving source code lines? I ran “git diff [hash1]..[hash2] –stat — lib/*.[ch] src/*.[ch]” for all years to get a summary of number of added and removed source code lines that year. I added those number to the table with surviving lines and then I made another graph:

year-again

Funnily enough, we see almost an exact correlation there for the first eight years and then the pattern breaks. From the year 2009 the number of removed lines went down but still the amount of surving lines went up quite a bit and then the graphs jump around a bit.

My interpretation of this graph is this boring: the amount of surviving code in absolute numbers is clearly correlating to the amount of added code. And that we removed more code yearly in the 2000-2003 period than what has survived.

But notice how the blue line is closing the gap to the orange/red one over time, which means that percentage wise there’s more surviving code in more recent code! How much?

Here’s the amount of surviving lines/added lines and a second graph looking at surviving lines/(added + removed) to see if the mere source code activity would be a more suitable factor to compare against…

relation survival vs added and removed lines

Code committed within the last 5 years are basically 75% left but then it goes downhill down to the 18% survival rate of the 1999 code import.

If you can think of other good info to dig out, let me know!

1999,1699
2000,1115
2001,3061
2002,2432
2003,2578
2004,7644
2005,4016
2006,5101
2007,7665
2008,7292
2009,9460
2010,11762
2011,19642
2012,11842
2013,16844

Another embedded hacking day

Monday, June 3rd, 2013

enea We started off this second embedded hacking day (the first one being the one we had in October) when I sent out the invitation email on April 22nd asking people to sign up. We limited the number of participants to 40, and within two hours all seats had been taken! Later on I handed out more tickets so we ended up with 49 people on the list and interestingly enough only 13 of these were signed up for the previous event as well so there were quite a lot of newcomers.Daniel Stenberg, a penguin

Arrival

At 10 in the morning on Saturday June 1st, the first people had already arrived and more visitors were dropping in one by one. They would get a goodie-bag from our gracious host with t-shirt (it is the black one you can see me wearing on the penguin picture on the left), some information and a giveaway thing. This time we unfortunately did not have a single female among the attendees, but the all-male crowd would spread out in the room and find seating, power and switches to use. People brought their laptops and we soon could see a very wide range of different devices, development boards and early design ideas showing up on the tables. Blinking leds and cables everywhere. Exactly the way we like it!

A table full of hackers and equipment!

Giveaway

A USB wifi thing

We decided pretty early on the planning for this event that we wouldn’t give away a Raspberry Pi again like we did last time. Not that it was a bad thing to give away, it was actually just a perfect gift, but simply because we had already done that and wanted to do something else and we reasoned that by now a lot of this audience already have a Raspberry pi or similar device.

So, we then came up with a little device that could improve your Raspberry Pi or similar board: a USB wifi thing with Linux drivers so that you easily can add wifi capabilities to your toy projects!

And in order to provide something that you can actually hack on during the event, we decided to give away an Arduino Nano version. Unfortunately, the delivery gods were not with us or perhaps we had forgot to sacrifice the correct animal or something, so this second piece didn’t arrive in time. Instead we gathered people’s postal addresseAns and once the package arrives in a couple of days we will send it out to all attendees. Sort of a little bonus present afterwards. Not the ideal situation, but hey, we did our best and I think this is at least a decent work-around.

So the fun begun

In the big conference room next to the large common room, I said welcome to everyone at 11:00 before I handed over to Magnus from Xilinx to talk about Xilinx Zynq and combining ARM and FPGAs. Magnus Lindblad, Xilinx The crowd proved itself from the first minute and Magnus got a flood of questions immediately. Possibly it was also due to the lovely combo that Magnus is primarily a HW-guy while the audience perhaps was mostly SW-persons but with an interest in lowlevel stuff and HW and how to optimize embedded systems etc.

Audience listening to Magnus

After this initial talk, lunch was served.

Contest

I got lots of positive feedback the last time on the contest I made then, so I made one this time around as well and it was fun again. See my separate post on the contest details.

Flying

After the dust had settled and everyones’ pulses had started to go back to normal again after the contest, Björn Stenberg “took the stage” at 14:00 and educated us all in how you can use 7 Arduinos when flying an R/C plane.

Björn talks about open source flying

Modellflyg med open source from bjornhaxx

Björn Stenberg, a penguin

It seemed as if Björn’s talk really hit home among many people in the audience and there was much talking and extra interest in Björn’s large pile of electronics and “stuff” that he had brought with him to show off. The final video Björn showed during his talk can be found here.

Stuff to eat

Buns for the masses!People actually want to get something done too during a day like this so we can’t make it all filled up with talks. Enea provided candy, drinks and buns. And of course coffee and water during the entire day.

Even with buns and several coffee refills, I think people were slowly getting soft in their brains when the afternoon struck and to really make people wake up, we hit them with Erik Alapää’s excellent talk…

Aliasing in C and C++

Or as Erik specified the full title: “Aliasing in C99/C++11 and data transfer between hard real-time systems on modern RISC processors”…

Erik helped put the light on some sides of the C programming language that perhaps aren’t the most used or understood. How aliasing can be used and what pitfalls it can send us down into!

Erik Alapää on C aliasing

Kjell Ericson's blinking ledsPersonally I don’t really had a lot of time or comfort to get much done this day other than making sure everything ran smooth and that everyone was happy and the schedule was kept. My original hopes was to get some time to do some debugging on a few of my projects during the day but I failed that ambition…

We made sure to videofilm all the talks so we should hopefully be able to provide online versions of them later on.

Real-time Linux

I took the last speaker slot for the day. I think lots of brains were soft by then, and a few people had already started to drop off. I talked for a while generically about how the real-time problem (or perhaps low-latency) is being handled with Linux these days and explained a bit about PREEMPT_RT and full dynamic ticks and what the differences of the methods are.

Daniel Stenberg talks Real-time Linux

Overview of Linux real-time challenges from Daniel Stenberg

The end

At 20:00 we forced everyone out of the facilities. A small team of us grabbed a bite and a couple of beers to digest the day and to yap just a little bit more before we split up for the evening and took off home…

Thank you everyone who was there for making it another great event. Thank you all speakers for giving the event the extra brightness! Thank you Enea for sponsoring, hosting and providing all the goodies in such an elegant manner! It is indeed possible that we make a 3rd embedded hacking day in the future…

Embedded hacking contest #2, decoded

Monday, June 3rd, 2013

Okay, so here are the correct answers to the embedded hacking #2 contest (click for larger pictures):

The contests correct answers marked

The fact that you get the clues as hexadecimal uppercase ASCII was pretty quickly clear to everybody. I found it interesting to hear how people attacked the problem of decoding the hex into letters. Most people seem to have made a lookup-table fairly soon, and at least one contestant I talked to made a mistake in his table that turned W into X instead! This year’s winner did the conversion completely without a written down table…

So all the pieces are decoded like this:

The final question

Of course, now a pedant would argue that FORK() isn’t correct, but I decided to use all uppercase just to make the conversion slightly easier. At least I think converting only uppercase ASCII as hex is easier. So the question is “What does fork() return in the child process?”

The answer to the question is 0 (zero). Short and simple. See fork’s man page.

Linus Nielsen Feltzing is the happy winner!

After 13 minutes and 20 seconds since I clicked start on the timer, Linus Nielsen Feltzing approached me with a little note with the correct answer and we had a winner!

The very happy Linus was very disappointed in the previous competition when he was very close to winning but was beaten just within seconds by last time’s winner.

Now, the Chromebook that Enea donated to the winner of the contest was handed over to Linus. (The Samsung Cortex-A15 version.)