Looking for kernel and embedded Linux experts
Bootlin is looking for experienced members of the Free Software community to satisfy increasing demand for development, consulting and training on embedded Linux and on the Linux kernel.
One thing that distinguishes our positions from others is that contributing to the community will be part of your objectives.
All the details can be found on our careers page.
Videos from the Embedded Linux Conference Europe, Grenoble, October 2009
Just a few weeks before the next edition of the Embedded Linux Conference in San Francisco, here are the videos from the previous edition in Europe a few months ago.
These videos were shot by Satoru Ueda and Tim Bird (Sony), Ruud Derwig (NXP) and by Thomas Petazzoni and Michael Opdenacker (Bootlin). As usual, they are released under the terms of the Creative Commons Attribution – ShareAlike Licence version 3.0.
If you have never been to an Embedded Linux Conference yet, these videos should show you how useful this conference is for embedded Linux system developers. This is the place where you can discover new development tools and technologies that will change your working life, benefit from the experience from your peers, get the opportunity to talk to the fantastic people who implement the Free and Open Source software that makes your system run, and win cool penguin goodies. So, don’t miss next next edition in San Francisco.
Welcome speech, by Ruud Derwig (NXP)
Customizing Embedded Linux Systems with PTXdist, by Robert Schwebel (Pengutronix)
e2factory – Open Source Embedded Linux Build System, by Gordon Hecker (Emlix)
State of real-time Linux: Don’t stop until history follows, by Philippe Gerum (Sourcetrek)
A Survey of Linux Measurement and Diagnostic Tools, by Frank Rowand (Sony)
Technical Features and Components of Open Source Build Systems, by Alex de Vries (Wind River Systems)
Analyzing Kernel Function Execution with Ftrace, by Tim Bird (Sony)
Linux Embedded Applications in Machine Vision, by Pascal Pellet (e2v)
U-Boot-v2, by Sascha Hauer, Marc Kleine-Budde (Pengutronix)
Porting Android to Power Architecture, by Nina Wilner (Power.org / IBM)
Genivi Alliance : An Effort to Build a Linux-based In Vehicle Infotainment Platform, by Jean-Marc Temmos (Visteon Software Technologies)
Mythbusters: Android, by Matt Porter (Mentor Graphics)Interesting features for embedded Linux system developers
Linux 2.6.33 was out on Feb. 24, 2010, and to incite you to try this new kernel in your embedded Linux products, here are features you could be interested in.
The first news is the availability of the LZO algorithm for kernel and initramfs compression. Linux 2.6.30 already introduced LZMA and BZIP2 compression options, which could significantly reduce the size of the kernel and initramfs images, but at the cost of much increased decompression time. LZO compression is a nice alternative. Though its compression rate is not as good as that of ZLIB (10 to 15% larger files), decompression time is much faster than with other algorithms. See our benchmarks. We reduced boot time by 200 ms on our at91 arm system, and the savings could even increase with bigger kernels.
This feature was implemented by my colleague Albin Tonnerre. It is currently available on x86 and arm (commit, commit, commit, commit), and according to Russell King, the arm maintainer, it should become the default compression option on this platform. This compressor can also be used on mips, thanks to Wu Zhangjin (commit).
For systems lacking RAM resources, a new useful feature is Compcache, which allows to swap application memory to a compressed cache in RAM. In practise, this technique increases the amount of RAM that applications can use. This could allow your embedded system or your netbook to run applications or environments it couldn’t execute before. This technique can also be a worthy alternative to on-disk swap in servers or desktops which do need a swap partition, as access performance is much improved. See this LWN.net article for details.
This new kernel also carries lots of improvements on embedded platforms, especially on the popular TI OMAP platform. In particular, we noticed early support to the IGEPv2 board, a very attractive platform based on the TI OMAP 3530 processor, much better than the Beagle Board for a very similar price. We have started to use it in customer projects, and we hope to contribute to its full support in the mainline kernel.
Another interesting feature of Linux 2.6.33 is the improvements in the capabilities of the perf tool. In particular, perf probe allows to insert Kprobes probes through the command line. Instead of SystemTap, which relied on kernel modules, perf probe now relies on a sysfs interface to pass probes to the kernel. This means that you no longer need a compiler and kernel headers to produce your probes. This made it difficult to port SystemTap to embedded platforms. The arm architecture doesn’t have performance counters in the mainline kernel yet (other architectures do), but patches are available. This carries the promise to be able to use probe tools like SystemTap at last on embedded architectures, all the more if SystemTap gets ported to this new infrastructure.
Other noticeable improvements in this release are the ability to mount ext3 and ext2 filesystems with just an ext4 driver, a lightweight RCU implementation, as well as the ability to change the default blinking cursor that is shown at boot time.
Unfortunately, each kernel release doesn’t only carry good news. Android patches got dropped from this release, because of a lack of interest from Google to maintain them. These are sad news and a threat for Android users who may end up without the ability to use newer kernel features and releases. Let’s hope that Google will once more realize the value of converging with the mainline Linux community. I hope that key contributors that this company employs (Andrew Morton in particular) will help to solve this issue.
As usual, this was just a selection. You will probably find many other interesting features on the Linux Changes page for Linux 2.6.33.
Tourist tips for participants to our training sessions in Nice, France.
We used to organize public training sessions about embedded Linux and kernel and drivers training sessions in Vence, near nice. The sessions are now run in Avignon, but we can still organize sessions for customers in the area, or anywhere in the world.
To explore the area, we recommend to rent a car. Cheap public transportation is available, but their service doesn’t go everywhere, and above all, doesn’t respect its schedules well. You should leave your car though, if you wish to visit the centers of Nice or Cannes. Traffic and parking rates are horrible, and a good solution is to park at a train station, and reach the center of these cities by local train.
Of course, these tips only reflect my own interests and tastes. There are certainly others other worthy things to do and see in the area. I would recommend to buy a tourist guide book about the French Riviera, which will have a much more exhaustive and objective coverage. See also the French Riviera tourism website.
Vence itself, where our sessions took place, is a nice medieval old town with very nice pedestrian streets. It takes just 5 minutes to reach the old town by foot from the hotel.
In the area, you mustn’t miss Saint Paul de Vence, a beautiful medieval village 3 kilometers away, which is famous worldwide. It is very nice to visit, though you may be disappointed by its lack of real life there. There are lots of foreign tourists and only art galleries and restaurants. If you look for similar but more authentic villages in the area, you can also visit Gourdon, Tourrettes sur Loup or Valbonne.
You shouldn’t miss Antibes either. It is the only well preserved old town on the sea shore, like the old villages uphill, Unlike Nice, and above all Monaco and Cannes, it’s an authentic place, with people like you and me, and less display of money and luxury.
I would suggest to visit Nice and Monaco, and skip Cannes, which doesn’t really have anything special the others don’t have. Nice has a nice old town, and a beautiful park above. You can also enjoy walking or roller skating on the beach front (La Promenade des Anglais).
I don’t find Monaco as attractive as it is famous. The old town and the castle are nice, but the whole area is very dense with lots of tall, ugly concrete buildings. One thing that you shouldn’t miss there is its amazing oceanographic museum.
I would still recommend to visit Monaco if you have enough time though, not for the place itself, but for the road between Nice and itself. You can go to Monaco through the Moyenne Corniche, a road on a very steep cliff and breathtaking views over the Mediterranean. A few James Bond movie scenes where shot there by the way, and the place should look familiar to you. On your way, you must stop at Èze, a beautiful village 1,200 feet above the sea. On the way back, you can take the Grande Corniche which offers a very nice scenery as well.
Even if you don’t have a car, you can hike up a hill on top of Vence, called the Baou des Blancs. Ask the hotel people for where the trail starts. On top of it, you will discover a fantastic view on the whole “Bay of Angels”. Depending on how fast you walk, you may need from 3 to 4 hours from Vence for the whole hike. If you have a car or take a taxi to get you to the beginning of the trail, 90 minutes may be sufficient.
If you have a car, good hiking shoes and enough time, you could visit the neighboring Alp mountains, locally culminating at more than 9,000 feet. In particular, you could go to the Valley of Marvels.
With the same equipment, you could also explore the Verdon Gorge, a spectacular canyon 90 minutes away from Nice.
If you have at least 2 days available, you could also go to the Cinque Terre in Italy, 3 hours away driving. You can also reach the place by train, though you may have 1 or 2 train connections on your way. Just look at the pictures.
You should also be interested in visiting Provence, within 1 to 3 hours of driving. This is one of the most celebrated parts of France, with beautiful scenery, monuments and a special “art de vivre”. There are so many things to do and see there that its worth buying a special book about it.
Last but not least, if you have at least 4 to 5 days, what about going to Corsica? You can reach this island by ferry boat (3 to 4 hours from Nice) or by plane. This is one of the most beautiful places on earth, with an amazing varianty of breathtaking landscapes: mountains, beaches, rivers. You won’t forget your stay.
Note: the materials for training with the Beagle Board are no longer available, and would be significantly out of date anyway. We advise you to check our Embedded Linux System Development and Linux Kernel and Driver Development training courses for up-to-date instructions that work on cheaper boards, which are still available on the market today. And if you still have an old Beagle board, it will be an interesting exercise to adapt our current labs to run them on such hardware.
We were asked to customize our embedded Linux training session with specific labs on OMAP 3530 hardware. After a successful delivery on the customer site, using Beagle boards, here are our training materials, released as usual under the terms of the Creative Commons Attribution-ShareAlike 3.0 license:
If you are the happy owner of such a board (both attractive and cheap), or are interested in getting one, you can get valuable embedded Linux experience by reading our lecture materials and by taking our practical labs.
Here’s what you would practise with if you decide to take our labs:
Note that the labs were tested with Rev. C boards, but are also supposed to work fine with Rev. B ones. You may also be able to reuse some of our instructions with other boards with a TI OMAP3 processor.
Of course, if you like the materials, you can also ask your company to order such a training session from us. We will be delighted to come to your place and spend time with you and your colleagues.
As usual, we won’t miss this year’s edition of the Embedded Linux Conference Europe, which has always been a great source of information and encounters for embedded Linux developers.
Here are details about our involvement this year.
Hope to see you in Grenoble!
Looking for kernel and embedded Linux experts
Bootlin is looking for experienced members of the Free Software community to satisfy increasing demand for development, consulting and training on embedded Linux and on the Linux kernel.
All the details can be found on our careers page.
To produce new HD videos from the Embedded Linux Conference, we needed a new script to add an introduction sequence to the videos we processed.
To make all this automatic, and to suppress the need to go through interactive tools (such as kdenlive) to produce a title with a fade-in / fade-out effect, I created a new theora-intro script. The process got much more complex than I expected, but fortunately, I got a lot of valuable advise and help from the Theora mailing list, and could hide all this complexity inside the script. That’s what scripts are for!
A nice feature. compared to the interactive video editors, is that no extra video processing pass is needed. Thanks to this, even a big video file can be processed within a few minutes. Another useful feature is that the script preserves the Ogg metadata (artist, title, location, copyright…).
So, if you wish to add an introduction sequence to your own videos, whatever their initial format, first convert them to Theora using ffmpeg2theora. Then, create a title image for your video, and then run theora-intro on it.
You can find all useful details on our theora-intro page.
My Colleague Thomas and I had the privilege to participate to the 2009 edition of the Embedded Linux Conference, which took place in San Francisco, on April 6-8. In spite of the weak economy, this event was once again a success. It attracted major developers from the embedded Linux community, as well as participants from all over the word.
Following the tradition, we are proud to release new videos about this event. These videos were shot by Satoru Ueda and Tim Bird (Sony), and by Thomas Petazzoni and Michael Opdenacker (Bootlin). For the first time, we used an HD camcorder to shoot some of the videos. A higher resolution allows to read the slides projected on the screen. As usual, the videos are released with a Creative Commons Attribution – ShareAlike 3.0 license.
Thomas and I found the following talks particularly interesting:
You may be interested in watching the presentations we made and the BOFs we led:
Of course, lots of other talks were very interesting. See the whole list by yourself:
Ubiquitous Linux, by Dirk Hohndel (Intel)
Update on filesystems for flash storage, by Michael Opdenacker (Bootlin)
Embedded Security BOF, by Matthew Locke (Embedded Alley)
Cooperative Development Inside Communities, by Jeffrey Osier-Mixon (MontaVista Software)
Video4Linux: What about Output ?, by Matthew Porter (Embedded Alley)
Maemo 5 (Fremantle), mobile Linux platform with cellular connectivity, by Kate Alhola (Nokia)
Ubuntu ARM Distribution, by David Mandala (Canonical)Add an introduction sequence to a Theora video
For the needs of producing conference videos, we developed a Python script to add an introduction sequence to a given Ogg/Theora video:
Usage: theora-intro [options] input-video title-image output-video
Adds an introduction to a source Ogg/Theora video, using the given title image
Options:
--version show program's version number and exit
-h, --help show this help message and exit
-v, --verbose Verbose mode
--artist=ARTIST Overrides the ARTIST Ogg metadata
--title=TITLE Overrides the TITLE Ogg metadata
--date=DATE Overrides the DATE Ogg metadata
--location=LOCATION Overrides the LOCATION Ogg metadata
--organization=ORGANIZATION
Overrides the ORGANIZATION Ogg metadata
--copyright=COPYRIGHT
Overrides the COPYRIGHT Ogg metadata
--license=LICENSE Overrides the LICENSE Ogg metadata
--contact=CONTACT Overrides the CONTACT Ogg metadata
This script was created especially for people who need to produce multiple videos, typically from the same event. So far, the only way to add an introduction video with fade-in and fade-out was through interactive video editors, such as kdenlive, and this required to encode the video again. Another reason to create a script is that the sequence of commands to run and the amount of data to extract and generate is rather complex. Having a script rather than just a howto thus reduces the risk of errors and mistakes.
All the releases of theora-intro can be found here.
To create an introduction sequence and concatenate it to the input video, theora-intro first needs to collect information from the input video. In particular, it reads the video width, height, the number of frames per seconds, as well as the audio bitrate and sample frequency, which need to be the same in the introduction sequence.
The introduction sequence shows the input title image (scaled), which fades in from a black picture, and eventually fades out to black again. The script actually generates a series of PNG images (using ImageMagick‘s convert utility), and converts this series into a video using ffmpeg2theora. Any input image format should work (JPG, GIF, PNG…), as ImageMagick supports most existing formats.
To be complete, the introduction sequence also needs an audio track. If it didn’t, the output video wouldn’t have any. Therefore, theora-intro generates a silent sample in WAV format, and converts it to Ogg/Vorbis.
The audio and video for the introduction sequence are then merged and concatenated. For some reasons still a bit unclear, the audio tracks of the introduction and input videos need to be resampled, but at last, there is no need to encode the video again. This makes theora-intro much faster than the time it takes to encode the video (just a few minutes even for big video files encoded in several hours).
You can find out more details by reading the code! It shoudn’t be difficult to understand it.
It is useful to produce Ogg/Theora videos with appropriate metadata (artist, title, location, copyright…). If the input video contains such metadata, these metadata are also replicated to the generated video. Note that theora-intro has options to override these metadata when needed, or when there are no such metadata in the input video.
This script relies on several software packages and libraries:
In Ubuntu and Debian, you can get the first four packages as follows:
sudo apt-get install vorbis-tools imagemagick ffmpeg2theora oggz-tools
Anyway, if any of the above packages is missing, theora-intro will let you know.
theora-intro was used to produce videos from the 2009 edition of the Embedded Linux Conference.
At the moment, videos generated with the latest release still show a few warnings with the ogginfo command:
$ ogginfo elc2009-bird-closing.ogv Processing file "elc2009-bird-closing.ogv"... New logical stream (#1, serial: 376a8b22): type theora New logical stream (#2, serial: 06fd37a7): type vorbis Theora headers parsed for stream 1, information follows... Version: 3.2.1 Vendor: Xiph.Org libTheora I 20081020 3 2 1 Width: 1280 Height: 720 Total image: 1280 by 720, crop offset (0, 0) Framerate 25/1 (25.00 fps) Aspect ratio undefined Colourspace: Rec. ITU-R BT.470-6 Systems B and G (PAL) Pixel format 4:2:0 Target bitrate: 0 kbps Nominal quality setting (0-63): 63 User comments section follows... TITLE=Tim Bird (Sony)- ELC Closing DATE=May 2009 LOCATION=San Francisco ORGANIZATION=Bootlin COPYRIGHT=Bootlin LICENSE=Creative Commons BY-SA 3.0 CONTACT=feedback@... ENCODER=ffmpeg2theora-0.23 Vorbis headers parsed for stream 2, information follows... Version: 0 Vendor: Xiph.Org libVorbis I 20070622 (1.2.0) Channels: 2 Rate: 48000 Nominal bitrate: 48.000000 kb/s Upper bitrate not set Lower bitrate not set User comments section follows... ENCODER=oggVideoTools 0.8 Warning: Expected frame 5265, got 5266 Warning: Expected frame 5270, got 5269 Warning: Expected frame 12663, got 12664 Warning: Expected frame 12667, got 12666 Warning: Expected frame 13657, got 13658 Warning: Expected frame 13660, got 13659 Warning: Expected frame 14213, got 14214 Warning: Expected frame 14218, got 14217 Warning: Expected frame 14875, got 14876 Warning: Expected frame 14879, got 14878 Warning: Expected frame 17635, got 17636 Warning: Expected frame 17638, got 17637 Vorbis stream 2: Total data length: 4322809 bytes Playback length: 11m:57.264s Average bitrate: 48.214426 kb/s Logical stream 2 ended Theora stream 1: Total data length: 49233283 bytes Playback length: 11m:57.320s Average bitrate: 549.080277 kb/s Logical stream 1 ended
These warnings don’t seem to create any issue in Ogg/Theora players. They are probably caused by an issue in the Ogg Video Tools, and we have reported this to their maintainer.