Embedded topics at the Libre Software Meeting, Geneva, July 9-11

Libre Software Meeting, Geneva
Libre Software Meeting, Geneva

The Libre Software Meeting is a community-driven free software event that exists since 2000, composed of talks and workshops. Its 2012 edition will take place from July 7th to July 12th in Geneva, Switzerland.

In the context of this conference, I was responsible with Florian Fainelli from the OpenWRT project to organize the Embedded systems and open hardware track. This track will offer an interesting selection of talks related to embedded topics, concentrated between July 9th and July 11th:

Geneva
Geneva

In the Operating Systems track, some other conferences might be of interested to Embedded Linux developers as well:

The entrace to the Libre Software Meeting is free, so don’t hesitate to book your train or flight tickets, and join us at this event!

Embedded Linux Conference 2012 videos

The 2012 edition of the Embedded Linux Conference took place on February 15-17th 2012 at Redwood Shores near San Francisco in California. Three engineers of Bootlin attended this conference, and we reported every day our impressions about the talks, see our blog posts for day 1, day 2 and day 3. We have now taken the time to encode all the videos we have recorded during this event, and are proud to distribute them today.

It is worth noting that for the first time, the Linux Foundation was also recording videos of the talks, the Linux Foundation videos are available from video.linux.com, and we included links to these videos below for the different talks.

We hope that those of you who couldn’t attend the conference will enjoy those videos, with many great talks on technical embedded Linux topics.

Jon CorbetVideo capture
Editor at LWN.net
The Kernel Report
Slides
Linux Foundation video
Bootlin video (53 minutes):
full HD (525M), 450×800 (154M)

Loïc PallardyVideo capture
Saving the Power Consumption of the Unused Memory
Slides
Bootlin video (46 minutes):
full HD (378M), 450×800 (125M)

Bernhard RosenkränzerVideo capture
Linaro
What Android and Embedded Linux Can Learn From Each Other
Slides
Linux Foundation video
Bootlin video (40 minutes):
full HD (370M), 450×800 (129M)

Ricardo Salveti de AraujoVideo capture
Linaro
Ubuntu on ARM: Improvements and Optimizations Done By Linaro
Slides
Linux Foundation video
Bootlin video (46 minutes):
full HD (301M), 450×800 (140M)

Zach PfefferVideo capture
Linaro
Binary Blobs Attack
Slides
Linux Foundation video
Bootlin video (50 minutes):
full HD (486M), 450×800 (157M)

Hisao MunakataVideo capture
Renesas Electronics
Close Encounters of the Upstream Resource
Slides
Linux Foundation video
Bootlin video (37 minutes):
full HD (394M), 450×800 (121M)

Daniel HurshVideo capture
IBM
Open Source Automated Test Framework
Slides
Bootlin video (45 minutes):
full HD (303M), 450×800 (132M)

Saul WoldVideo capture
Intel
The Yocto Project Overview and Update
Slides
Linux Foundation video
Bootlin video (54 minutes):
full HD (543M), 450×800 (171M)

Sean HudsonVideo capture
Mentor Graphics, Inc.
Embedded Linux Pitfalls
Slides
Bootlin video (51 minutes):
full HD (483M), 450×800 (176M)

Vincent GuittotVideo capture
Linaro
Comparing Power Saving Techniques For Multicore ARM Platforms
Slides
Linux Foundation video
Bootlin video (57 minutes):
full HD (307M), 450×800 (154M)

Tim BirdVideo capture
Sony Network Entertainment
Status of Embedded Linux
Slides
Linux Foundation video
Bootlin video (49 minutes):
full HD (492M), 450×800 (159M)

Bruce AshfieldVideo capture
Wind River
A View From the Trenches: Embedded Functionality and How It Impacts Multi-Arch Kernel Maintenance
Slides
Bootlin video (54 minutes):
full HD (741M), 450×800 (222M)

R DurgadossVideo capture
Intel
PeakCurrent Management in x86-Based Smartphones
Slides
Linux Foundation video
Bootlin video (50 minutes):
full HD (296M), 450×800 (141M)

Matt PorterVideo capture
Texas Instruments
Passing Time With SPI Framebuffer Driver
Slides

Bootlin video (54 minutes):
full HD (565M), 450×800 (172M)

WookeyVideo capture
Linaro
Multiarch and Why You Should Care: Running, Installing and Crossbuilding With Multiple Architectures
Slides
Bootlin video (42 minutes):
full HD (453M), 450×800 (143M)

Amit Daniel KachhapVideo capture
Linaro/Samsung
A New Simplified Thermal Framework For ARM Platforms
Slides
Linux Foundation video
Bootlin video (41 minutes):
full HD (226M), 450×800 (115M)

Tsugikazu ShibataVideo capture
NEC
On The Road: To Provide the Long-Term Stable Linux For The Industry
Slides
Linux Foundation video
Bootlin video (32 minutes):
full HD (304M), 450×800 (95M)

Thomas P. AbrahamVideo capture
Samsung Electronics
Experiences With Device Tree Support Development For ARM-Based SOC’s
Slides
Bootlin video (44 minutes):
full HD (509M), 450×800 (155M)

Paul E. McKenneyVideo capture
IBM
Making RCU Safe For Battery-Powered Devices
Slides
Linux Foundation video
Bootlin video (52 minutes):
full HD (506M), 450×800 (186M)

Mike AndersonVideo capture
Chief Technology Officer at The PTR Group
The Internet of Things
Slides
Linux Foundation video
Bootlin video (50 minutes):
full HD (580M), 450×800 (186M)

Thomas PetazzoniVideo capture
Bootlin
Buildroot: A Nice, Simple, and Efficient Embedded Linux Build System
Slides
Linux Foundation video
Bootlin video (56 minutes):
full HD (594M), 450×800 (182M)

Steven RostedtVideo capture
Red Hat
Automated Testing with ktest.pl (Embedded Edition)
Slides
Linux Foundation video
Bootlin video (102 minutes):
full HD (1,2G), 450×800 (354M)

David VomLehnVideo capture
Cisco
Intricacies of a MIPS Stack Backtrace Implementation
Slides
Linux Foundation video
Bootlin video (52 minutes):
full HD (345M), 450×800 (153M)

Edward HerveyVideo capture
Collabora
GStreamer 1.0: No Longer Compromise Flexibility For Performance
Slides
Linux Foundation video
Bootlin video (49 minutes):
full HD (540M), 450×800 (174M)

Tim BirdVideo capture
Sony Network Entertainment
Embedded-Appropriate Crash Handling in Linux
Slides
Linux Foundation video
Bootlin video (49 minutes):
full HD (292M), 450×800 (142M)

Arnd BergmannVideo capture
Linaro
ARM Subarchitecture Status
Slides
Linux Foundation video
Bootlin video (49 minutes):
full HD (416M), 450×800 (140M)

Mark GisiVideo capture
Wind River Systems
The Power of SPDX – Sharing Critical Licensing Information Within a Linux Device Supply Chain
Linux Foundation video
Bootlin video (49 minutes):
full HD (498M), 450×800 (164M)

Yoshitake KobayashiVideo capture
Toshiba
Ineffective and Effective Ways To Find Out Latency Bottlenecks With Ftrace
Slides
Linux Foundation video
Bootlin video (37 minutes):
full HD (251M), 450×800 (108M)

Ohad Ben-CohenVideo capture
Wizery / Texas Instruments
Using virtio to Talk With Remote Processors
Slides
Linux Foundation video
Bootlin video (54 minutes):
full HD (582M), 450×800 (182M)

Elizabeth FlanaganVideo capture
Intel
Embedded License Compliance Patterns and Antipatterns
Linux Foundation video
Bootlin video (44 minutes):
full HD (391M), 450×800 (144M)

David AndersVideo capture
Texas Instruments
Board Bringup: LCD and Display Interfaces
Slides
Linux Foundation video
Bootlin video (40 minutes):
full HD (207M), 450×800 (113M)

Rob ClarkVideo capture
Texas Instruments
DMA Buffer Sharing: An Introduction
Slides
Linux Foundation video
Bootlin video (35 minutes):
full HD (306M), 450×800 (100M)

Ken ToughVideo capture
Intrinsyc
Linux on eMMC: Optimizing For Performance
Slides
Linux Foundation video
Bootlin video (52 minutes):
full HD (468M), 450×800 (165M)

Paul LarsonVideo capture
Linaro
LAVA Project Update
Slides
Linux Foundation video
Bootlin video (52 minutes):
full HD (366M), 450×800 (159M)

Frank RowandVideo capture
Sony Network Entertainment
Real Time (BoFs)
Slides
Bootlin video (77 minutes):
full HD (924M), 450×800 (288M)

Mike TurquetteVideo capture
Texas Instruments
Common Clock Framework (BoFs)
Slides
Bootlin video (53 minutes):
full HD (333M), 450×800 (148M)

Hunyue YauVideo capture
HY Research LLC
Userland Tools and Techniques For Linux Board Bring-Up and Systems Integration
Slides
Linux Foundation video
Bootlin video (51 minutes):
full HD (407M), 450×800 (136M)

Matt WeberVideo capture
Rockwell Collins Inc.
Optimizing the Embedded Platform Using OpenCV
Slides
Linux Foundation video
Bootlin video (37 minutes):
full HD (388M), 450×800 (125M)

Greg UngererVideo capture
McAfee
M68K: Life in the Old Architecture
Slides
Linux Foundation video
Bootlin video (46 minutes):
full HD (452M), 450×800 (166M)

Gary BissonVideo capture
Adeneo Embedded
Useful USB Gadgets on Linux
Slides
Linux Foundation video
Bootlin video (43 minutes):
full HD (402M), 450×800 (129M)

Jason KridnerVideo capture
Texas Instruments
GUIs: Coming To Uncommon Goods Near You
Slides
Linux Foundation video
Bootlin video (52 minutes):
full HD (476M), 450×800 (166M)

Mike AndersonVideo capture
The PTR Group
Adapting Your Network Code For IPv6 Support
Slides
Linux Foundation video
Bootlin video (63 minutes):
full HD (485M), 450×800 (216M)

Koen KooiVideo capture
The Angstrom Distribution
Producing the Beaglebone and Supporting It
Linux Foundation video
Bootlin video (42 minutes):
full HD (398M), 450×800 (126M)

Danny BennettVideo capture
basysKom GmbH
HTML5 in a Plasma-Active World
Slides
Linux Foundation video
Bootlin video (34 minutes):
full HD (258M), 450×800 (75M)

Marcin MielczarczykVideo capture
Tieto
Getting the First Open Source GSM Stack in Linux
Slides
Linux Foundation video
Bootlin video (54 minutes):
full HD (439M), 450×800 (178M)

Pierre TardyVideo capture
Intel
PyTimechart Practical
Slides
Linux Foundation video
Bootlin video (32 minutes):
full HD (260M), 450×800 (86M)

Linus WalleijVideo capture
ST-Ericsson
Pin Control Subsystem Overview
Slides
Linux Foundation video
Bootlin video (60 minutes):
full HD (638M), 450×800 (200M)

Khem RajVideo capture
OpenEmbedded Project
OpenEmbedded – A Layered Approach
Slides
Linux Foundation video
Bootlin video (39 minutes):
full HD (227M), 450×800 (108M)

Lucas De MarchiVideo capture
ProFUSION Embedded Systems
Managing Kernel Modules With kmod
Slides
Linux Foundation video
Bootlin video (46 minutes):
full HD (443M), 450×800 (140M)

Jean PihetVideo capture
NewOldBits
A New Model for the System and Devices Latency
Slides
Bootlin video (49 minutes):
full HD (431M), 450×800 (146M)

Android Builders Summit 2012 videos

On February 13-14th 2012, the second edition of the Android Builders Summit took place in Redwood Shores, near San Francisco in California. While Bootlin was not officially in charge of video recording for this conference, we recorded the talks we attended and that we are glad to share below. The Linux Foundation has also recorded those talks (except a few of them for which they had technical issues), and we provide those additional links below. You can also follow our reports from day 1 and day 2 of this conference.

You’ll find below our videos of the main talks we recorded, and also the videos of the lightning talks that took place on the evening of the first day of the conference. Enjoy!

Main talks

Karim YaghmourVideo capture
Opersys
Leveraging Linux’s History With Android
Slides
Bootlin video (32 minutes):
full HD (386M), 450×800 (107M)

Arnd Bergmann, Tim Bird, Greg Kroah-Hartmann, Zach Pfeffer, moderated by Jonathan CorbetVideo capture
IBM/Linaro, Sony Network Entertainment, The Linux Foundation, Linaro, LWN.net
Panel: Android and the Linux Kernel Mainline: Where Are We?
Bootlin video (38 minutes):
full HD (525M), 450×800 (156M)

Marko GargentaVideo capture
Marakana
Customizing Android
Slides
Linux Foundation video
Bootlin video (50 minutes):
full HD (409M), 450×800 (131M)

Tetsuyuki KobayashiVideo capture
Kyoto Microcomputer
How ADB(Android Debug Bridge) Works
Slides
Linux Foundation video
Bootlin video (33 minutes):
full HD (365M), 450×800 (100M)

Andrew BoieVideo capture
Intel
Android OTA SW Updates
Slides
Linux Foundation video
Bootlin video (61 minutes):
full HD (698M), 450×800 (189M)

Benjamin ZoresVideo capture
Alcatel-Lucent
Android Device Porting Walkthrough
Slides
Linux Foundation video
Bootlin video (69 minutes):
full HD (534M), 450×800 (179M)

Jason Kridner, Khasim Syed MohammedVideo capture
Texas Instruments
Using Android outside of the Mobile Phone Space
Slides
Linux Foundation video
Bootlin video (34 minutes):
full HD (414M), 450×800 (120M)

Tom MossVideo capture
3LM
The Android Ecosystem
Linux Foundation video
Bootlin video (27 minutes):
full HD (267M), 450×800 (82M)

Karim YaghmourVideo capture
Opersys
Headless Android
Slides
Bootlin video (50 minutes):
full HD (462M), 450×800 (145M)

Tom FoyVideo capture
Intrinsyc
Android on eMMC: Optimizing for Performance
Slides
Bootlin video (34 minutes):
full HD (234M), 450×800 (90M)

Wolfgang MauererVideo capture
Siemens
Real-Time Android
Slides
Bootlin video (59 minutes):
full HD (418M), 450×800 (155M)

Jim HuangVideo capture
0xlab
Improve Android System Component Performance
Slides
Linux Foundation video
Bootlin video (54 minutes):
full HD (457M), 450×800 (152M)

Rodrigo ChiossiVideo capture
Samsung
AndroidXRef: Speeding up the Development of Android Internals
Slides
Linux Foundation video
Bootlin video (38 minutes):
full HD (313M), 450×800 (108M)

Mark BrownVideo capture
Wolfson Microelectronics
Towards a Standard Audio HAL for Android
Slides
Linux Foundation video
Bootlin video (47 minutes):
full HD (227M), 450×800 (123M)

Jen CostilloVideo capture
Topics in Designing An Android Sensor Subsystem: Pitfalls and Considerations
Slides
Linux Foundation video
Bootlin video (36 minutes):
full HD (238M), 450×800 (101M)

Aleksandar (Saša) GargentaVideo capture
Marakana
Android Services Black Magic
Linux Foundation video
Bootlin video (61 minutes):
full HD (410M), 450×800 (169M)

Lightning talks

Dario LaverdeVideo capture
HTC
HTC Dev
Bootlin video (3 minutes):
full HD (44M), 450×800 (13M)

Robert McQueenVideo capture
Collabora
Integrating GStreamer and PulseAudio in Android
Bootlin video (4 minutes):
full HD (49M), 450×800 (16M)

Mark GrossVideo capture
Intel
Android build times and host tweakage
Bootlin video (4 minutes):
full HD (37M), 450×800 (13M)

Tony ManssonVideo capture
Linaro
Painless debugging of native code in Android-based device (using DS-5)
Bootlin video (4 minutes):
full HD (32M), 450×800 (13M)

Paul ArssovVideo capture
ARS Technologies Inc.
How easy is it to support external hardware on Android platform
Bootlin video (4 minutes):
full HD (33M), 450×800 (13M)

Karim YaghmourVideo capture
Opersys
Cyborgstack
Bootlin video (4 minutes):
full HD (60M), 450×800 (18M)

Yahya MirzaVideo capture
Aurora Borealis Software
Towards a heterogeneous application for compute driver performance testing and analysis
Bootlin video (3 minutes):
full HD (47M), 450×800 (14M)

Joe BornVideo capture
Sonrlabs
Sonr, Serial headphone interface and hardware
Bootlin video (4 minutes):
full HD (38M), 450×800 (13M)

Embedded Linux Conference day 3

Finally, the last day of the 2012 edition of the Embedded Linux Conference has arrived. Including the Android Builders Summit, it was a very busy week with five full days of presentations, a very intensive learning session, but also highly motivating and refreshing. Here is, with a little bit of delay, the report of this last day.

Thanks to the kind help of Benjamin Zores (from Alcatel/Lucent, the GeeXboX and OpenBricks projects) who kindly accepted to record the Userland Tools and Techniques For Linux Board Bring-Up and Systems Integration, both Grégory and myself could attend the talk from Greg Ungerer titled M68K: Life in the Old Architecture. Greg started with a very nice and clear explanation of the history of the 68k architecture from a hardware perspective, and detailed its evolution into the Coldfire architecture. The history is quite complicated: the first 68k processors had no MMU, and then MMU was added starting at the 68030 family. However, when Freescale started with Coldfire, which uses a subset of the 68k instruction set, they removed the MMU, until Coldfire V4e, on which an MMU is available. Originally, the Linux port in arch/m68k only supported the classic 68k with MMU, and support for non-MMU Coldfires was added in uClinux. Later, support for non-MMU Coldfires was added into the mainline kernel in arch/m68knommu, with unfortunately a lot of duplication from arch/m68k. The two directories have been merged again some time ago: the merge had already been done in a mechanic fashion (merging identical files, renaming different files that had similar names), and a huge cleanup effort has taken place since then. The cleanup effort is not completely done yet, but it’s getting close, according to Greg Ungerer. At the end of the session, there has been a question on how m68k/coldfire developers typically generate their userspace, and Greg said he uses something similar to Buildroot, which in fact is uClinux-dist. I jumped in, and said that we would definitely like to have Coldfire support, especially since the activity on uClinux-dist isn’t very strong. I also asked what were the remaining differences between the uClinux kernel and the mainline kernel, and according to Greg, there is almost no difference now except maybe support for a few boards. Greg only uses the mainline Linux kernel now for his m68k and Coldfire developments.

The next conference I attended was the talk from Gary Bisson (Adeneo Embedded) titled Useful USB Gadgets on Linux. I rescued the speaker by lending my laptop because his laptop had no VGA output. Fortunately, the speaker was French, so he could adapt quickly to our bizarre azerty keyboard layout. Gary gave quite a bit of context on what USB is, and explained the USB terminology such as interfaces, end-points, configurations, etc. He then quickly described the Linux USB Gadget stack and gadgetfs for the implementation of USB gadget drivers in userspace. He then presented the existing USB gadget drivers in the kernel, mainly the zero gadget driver (for testing purposes), the mass storage gadget driver, the serial gadget driver and the Ethernet gadget driver. At the end of the presentation, he made a demonstration on a BeagleBoard-XM with the gadget multi driver, which allows to expose multiple gadget interfaces at the same time. So he showed that he could expose the Ethernet interface, the Mass Storage interface and the Serial interface, and demonstrated their usage from the host machine. Overall the talk was good, but I was personally expecting a more in-depth look at USB Gadget driver development, and not only usage: I have already been using gadget drivers for some time now, and I was more interested in having details on developing custom gadget drivers rather than simply on using the existing ones.

Bootlin engineering team. From left to right: Grégory Clément, Maxime Ripard and Thomas Petazzoni
Bootlin engineering team (missing: Michael Opdenacker). From left to right: Grégory Clément, Maxime Ripard and Thomas Petazzoni

After a quick break, Grégory and I attended the Getting the First Open Source GSM Stack in Linux talk by Marcin Mielczarczyk from Tieto. It was an absolutely excellent talk. Marcin described the work he and one of his colleague did to reverse engineer a cheap Chinese phone and port U-Boot and Linux on it. Marcin started by giving details about the landscape of those cheap Chinese phones, and it was quite funny: there are brands like Nokla, Sany Eracsson or SciPhone that create phones that are similar in shape and design to phones from the original brands, but with completely different hardware, and usually completely different software. Marcin said that the great thing about those phones is that they are really cheap (which is nice when you need to do some hardware modifications on them for reverse engineering purposes), can easily be bought from auction sites like eBay, and usually do not use any sort of encryption or signature mechanism to prevent the execution of a different operating system or bootloader. The motivation of Marcin in getting Linux to run on such a phone was to ultimately be able to run the complete OsmocomBB software GSM stack inside the phone. OsmocomBB is a free software implementation of a GSM communication stack, lead by Harald Welte. For the moment, the OsmocomBB project uses phones based on the Calypso based-band processor, and only use the phone for the layer 1 (physical layer) of the communication, while the above layers (layer 2 and 3) are implemented in a PC that communicates with the phone over a serial port. Marcin would like to integrate everything inside the phone itself, in order to make the free software GSM stack completely autonomous and fully usable directly on the phone. Marcin decided to pick the SciPhoneDreamG2, a phone that uses the Mediatek 6235 processor, which has the great advantage of being an ARM9 processor, allowing to run a full-blown Linux, and having a datasheet available on the Web. The original operating system of the phone is Nucleus, on top of which the Chinese brand has added an interface that completely mimics Android but is not Android at all. Marcin described the work he did to understand where the UART port and JTAG port was connected (for this work, he mentioned the usage of the JTAG finder project, a software one can run on a micro-controller and that automatically finds which pins are the JTAG pins of a processor). Once he had access to a serial console and the JTAG, he dumped the memory, and started understanding how the boot process was working, and how the existing boot loader was initializing the DRAM. This work was completely done by disassembling the code, which required quite some effort, according to Marcin. Once this was done, he said that porting U-Boot only required creating a basic UART driver and a timer driver, and porting a basic Linux only required a similar UART driver and timer driver, but also an interrupt driver. Marcin and his colleague then went one in developing the other drivers, such as SD, USB, GPIOs and more, and they detailed some of the issues they faced and the time required for these different tasks. In the end, the project is not yet finished, since OsmocomBB does not run on the phone yet, but this is the next goal for Marcin and his colleague. In the end, it was a very interesting goal, detailing in an informative and amusing way an absolutely excellent reverse-engineering effort conducted by Marcin. I would strongly recommend watching the video of this talk.

Pin Control Subsystem Overview Linus Walleij
Pin Control Subsystem Overview Linus Walleij

The last afternoon of ELC started with a talk from Linus Walleij from Linaro, Pin Control Subsystem Overview. Linus Walleij started by describing with lots of details how I/O pins are implemented from a hardware perspective. He first described a basic I/O pin, on which the software can just control the level. On top of this, he explained the hardware logic used to generate interrupts and wake-up events from I/O pins. And finally, he added that those I/O pins are nowadays commonly multiplexed since the SoC do not have enough pins to expose all their possible features, so a given pin can be used either for one function (say, one pin of a I2C bus) or another function (say, one pin of a parallel LCD interface) or as a general purpose I/O. Since this multiplexing is controlled by software, the code for the various ARM sub-architectures in the Linux kernel have each implemented their own little framework and API to solve that problem, and it’s up to each board file to set their I/O multiplexing settings. Unfortunately, since each ARM sub-architecture has its own implementation, there is no coherent API, and there is code duplication. Linus Walleij’s pin mux subsystem intends to solve that. It has already been merged in mainline, in the drivers/pinctrl directory, and a few ARM sub-architectures have started using it, with more to come in the near future, said Linus. Basically, the pinmux subsystem allows to describe which pins are available on the SoC, how they are grouped together in functions, and how drivers can select which function should be activated at an I/O multiplexing level. Of course, the pinmux subsystem detects conflicting usage of I/O, for example if two different drivers want to use the same pin with a different function. Linus also clarified how drivers for I/O pins block should be implemented in the kernel now. If what you have is a simple GPIO expander, then the driver for it should lie in drivers/gpio and it should use the gpio_chip structure. If this simple GPIO expander is also capable of generating interrupts, then the driver should still be in drivers/gpio, but in addition to the gpio_chip structure, it should also register an irq_chip structure. And finally, if instead this I/O pin controller supports multiplexing, then the driver for it should be implemented in drivers/pinctrl, and it should register into the GPIO subsystem (through the gpio_chip structure), into the IRQ subsystem (through the irq_chip structure) and into the pinmux subsystem (through the pinctrl_desc and other related structures). All in all, Linus’s presentation was a great talk, but I wished he would have put more details on the actual API and data structures: his description of the data structures through UML diagrams were a bit hard to follow.

For the last session of the day, I initially planned to attend Pintu Kummar’s talk on Controlling Linux Memory Fragmentation and Higher Order Allocation Failure: Analysis, Observations and Results, but this session was unfortunately canceled. Therefore, I joined my colleague Maxime Ripard and attended Lucas de Marchi talk about Managing Kernel Modules With kmod. Basically, about a year ago, Lennart Poettering, developer of the systemd new userspace init implementation for Linux, listed a set of topics that he wanted to see improved in Linux to make the initialization sequence perform better. Amongst them was the development of a userspace library to manage kernel modules (query information, insert and remove modules). The problem is that until now, the only way to load and remove modules was to call the modprobe, insmod or rmmod programs, which for each module load operation, required a costly sequence of fork/exec. Since udev tries to load up to 200-300 modules at startup (sometimes just to discover that the module is already loaded), this takes a significant amount of time. So Lucas de Marchi, who works at ProFUSION, decided to step up, and did the implementation of kmod. kmod is composed of a C library which implements the core logic of the module information query, module loading and module removal operation, supporting all the fine details that modprobe was supporting (such as dependency handling, module aliases and the configuration files in /etc/modprobe.d/ with options for modules, blacklisted modules). kmod also contains replacement programs for the insmod, lsmod, rmmod and modprobe programs, directly inside a single kmod binary, with symlinks pointing to it for the various commands. kmod is now a full replacement for the old module-init-tools, which has been marked as obsolete by his former maintainer, Jon Masters (who has joined the kmod project). Desktop distributions have started to pick up kmod (Arch Linux, Fedora, and Debian in experimental), as well as embedded Linux build systems. Lucas mentioned that Buildroot had the latest version of kmod, while OpenEmbedded had a slighly older version, and that he didn’t know about other build systems. In the end, this kmod project does not bring a lot of new features or innovations, but is a well-appreciated initiative to make module management better in Linux. What’s very impressive in the time frame in which the project was done: in about a year, the project got started, the development was done, and it is now a full replacement of the old solution, which has been marked deprecated. Great job!

Managing Kernel Modules With kmod, Lucas De Marchi
Managing Kernel Modules With kmod, Lucas De Marchi

Finally, as every ELC, the conference was closed with a game involving all the attendees, and allowing to win nice prizes such as development boards, USB scopes, audio/video portable players (PMPs), and more. The game started with a set of geek questions (such as “Will the Linux kernel in version 3.3 have more or less than 15 millions lines of code ?”, or “Is the distance from the Earth to the Moon smaller or higher than 150.000 miles ?”), and then a rock/paper/scissors game, and finally a raffle. This closing game is always a nice way of ending ELC.

This year’s edition of the Android Builders Summit and the Embedded Linux Conference have been great, with lots of interesting technical talks, and lots of side discussions with various developers. Many thanks to the conference organizers and speakers!

Embedded Linux Conference Europe 2012
Embedded Linux Conference Europe 2012

We hope that those five blog posts reporting some details about those conferences have been interesting to those who didn’t have the chance to attend, and we are definitely looking forward the next edition of the Embedded Linux Conference Europe, which will take place in Barcelona from November 5th to November 7th. Note that the call for papers has already been published. It’s time to think about what you’re doing in the embedded Linux world, and to propose a corresponding talk!

Embedded Linux Conference day 2

Day 2 of the Embedded Linux Conference started with a keynote titled The Internet of Things, given by Mike Anderson. With such a title, one could have feared some kind of very fuzzy-marketing-style kind of keynote, but with Mike Anderson as speaker, it clearly couldn’t be the case. Mike is well-known at ELC and ELCE for all its highly technical presentation on kernel debugging, JTAG, OpenOCD and more. This keynote was not really related to embedded Linux directly, but about all the potential applications that modern technologies such as RFID, nano-robots, wireless communications have. As Mike pointed out, there are lots of potential opportunities to optimize energy usage, make our lives easier, but there are also lots of dangers (surveillance, manipulation of information, reduction of private life, etc.).

The Internet of Things, Mike Anderson
The Internet of Things, Mike Anderson

Right after Mike’s keynote, it was the time for me to give the presentation Buildroot: A Nice, Simple, and Efficient Embedded Linux Build System. As a presenter, I am obviously not objective, but I think the presentation went well. I filled the entire time slot, leaving the time for about five questions at the end. Around 60-70 people were in the room, quite a good number considering the fact that there was a talk from the excellent Steven Rostedt in another room at the same time. I will put the slides of this presentation on line very soon, which was a general presentation of Buildroot, trying to emphasize all the cleanups and quality improvements we have done since the last three years, and also trying to highlight the fact that Buildroot is really easy to understand, it is not a magic black box contrary to some other embedded Linux build systems. That’s the reason why I gave some details about how our package infrastructure works internally, to show that it is really simple. There were several questions about why we do not support binary packages, and of course I replied that it was a design decision in order to remain simple. At the end of the presentation, a guy from Mentor Graphics came to tell me that saying no was an excellent thing and that too many projects fail to say no to new features, and therefore they get more and more complicated.

At the same time as my Buildroot’s talk, Steven Rostedt from RedHat was presenting Automated Testing with ktest.pl (Embedded Edition) and Grégory attended this conference. Grégory reports: “As indicated in the title it is the “embedded” version of a former conference. I don’t know if Steven is really new in the embedded field or if he just pretends to, but the result is that for a newcomer in embedded Linux, this talk is really well detailed. He shows how to setup the board step by step, showing the problems you usually have. But the real topic is the ktest.pl script and how to use it. After two hours of presentation I was totally convinced by the usefulness of this script. It will help a lot to automate the tasks we usually do by hand such as git bisect, check that the stack of patches we have don’t break anything, check that we don’t have any regression at runtime or just at build. All these tasks can be done with ktest.pl and in a very simple way!”

Automated Testing with ktest.pl (Embedded Edition), Steven Rostedt
Automated Testing with ktest.pl (Embedded Edition), Steven Rostedt

Then, I went to Tim Bird’s talk about Embedded-Appropriate Crash Handling in Linux. The initial problem that Tim wanted to solve is how to get and store information about applications that have crashed on devices in the-field. The major issue is that to debug and understand the crash you theoretically need to keep a lot of information, but in practice you cannot do this due to space constraints. Typically, a way of doing post-mortem analysis of a crashed application is to use the core file that the kernel generates after the crash, and use it with gdb. Unfortunately, a core file is typically very large. Tim looked at the crash report mechanism of Android, and discovered that it was directly registering a handler for the SIGSEGV signal (and other related signals indicating an application crash) into the dynamic library loader in Bionic. This signal handler communicates with a daemon called debuggerd over a socket, and this daemon then uses ptrace to get details about the state of the application at the moment of the crash (register values, stack contents, etc.). Tim didn’t want to require modifications at the application level or at the dynamic library loader, so instead he used the core pattern mechanism provided by the Linux kernel: by writing to some file in /proc, you can tell the kernel to start a userspace program when an application crashes, and the kernel dumps the core file contents as the standard input of this new process. Based on debuggerd, Tim implemented such a program that also uses ptrace and /proc to get details about the crashed application. Tim also discussed the various ways of getting a backtrace: using the frame pointer (but this is often not available, as many people use the -fomit-frame-pointer compiler option), using the unwind tables, using a best-guess method (you just go through the stack, and everything that looks like a valid function address is assumed to be part of the call stack, so this method shows some false positive) or using some kind of ARM emulation (but I don’t recall the name of this solution at the moment). All in all, Tim’s talk was great, a good report of its experiment and good technical information about this topic.

Everybody at Bootlin wanted to attend to the “ARM Subarchitecture Status” presentation given by Arnd Bergmann, but we couldn’t since we were responsible for recording videos of all talks. This time, it’s Grégory who had the privilege of attending what looked like the most interesting talk of the slot. In fact as we follow the ARM Linux community in a close way through the mailing lists or the LWN.net website, nothing was really new for Grégory in Arnd’s presentation. Nevertheless it was good to take the time to have a status. The interesting part for Grégory was to see how Arnd works with all the git trees coming from SoC vendors or from community and how he merges them together and merges the conflicts. It is more manual than we imagined and honestly is certainly a very hard job to do.

ARM Subarchitecture status, Arnd Bergmann
ARM Subarchitecture status, Arnd Bergmann

Later in the day, I went to David Anders talk about Board Bringup: LCD and Display Interfaces and it was really a great talk. David explained very well the hardware signals between the LCD controller that you have in your SoC and the LCD panel you’re using, and how those signals affect the timing configuration that you have to set in your kernel code. He clearly explained things like pixel clock, vertical and horizontal sync, but also more complex things like the front porch and the back porch. He then went on to describe LVDS, which in fact is a serial protocol that uses two wires per-color in a differential mode to transmit the picture contents, and also talked about EDID, which is basically an I2C bus that can be used to read from the display device what display modes are available and what their timings are. He also described some of the test methods he used, from a logic analyzer up to a program called fb-test. David’s talk was really great because it provided the kind of hardware details that a low-level software engineer needs to understand, and David explained them in a way that can be understood by a software engineer. Following the talk, I met David and asked some more questions and he was very nice to answer them, in a very clear way. David slides are available at http://elinux.org/Elc-lcd, and you can also check out other things that David is working on at TinCanTools, such as the very nice Flyswatter JTAG debugger for ARM.

At the end of day, Grégory attended the Real-Time discussion session, Maxime attended the Yocto Project discussion session and I attended the Common Clock Framework discussion session. This last discussion session was about work done to consolidate the multiple implementations of the clock APIs that exist in the kernel: at the moment, each ARM sub-architecture re-implements its own clock framework and the goal is to have a common clock framework in drivers/clk/ that can be shared by all ARM sub-architectures but also potentially by other architectures as well. The discussion lead by Mike Turquette from Texas Instruments/Linaro showed that a great deal of work has already been done, but a lot of questions remained opened. Each ARM sub-architecture has different constraints, and finding the right solution that solves the constraints of everybody isn’t easy.

And finally, there was the usual Technical Showcase, with demonstrations of the Pandaboard, but also the newer BeagleBone platform which looks really exciting. David Anders was demonstrating his LCD bring-up setup, another person was demonstrating an open-source GSM access point based on USRP, etc. Lots of interesting things to see, lots of nice people to discuss with.

Embedded Linux Conference day 1

The first day of the Embedded Linux Conference started on Wednesday here at Redwood City, California.

The day started with the usual Kernel Report from Jonathan Corbet. It was, as usual with Corbet’s talk, a very interesting summary of what happened in the kernel through the last year, with highlights of the major new features per release, thoughts about issues like the kernel.org security problem and subsequent outage, etc.

The Kernel Report, Jonathan Corbet
The Kernel Report, Jonathan Corbet

After this talk, Grégory went to the Saving the Power Consumption of the Unused Memory talk, given by Loïc Pallardy, who works for ST Ericson in France. The purpose of the talk was to detail the kernel modifications they made to support the fact of powering down portions of the memory that are unused. In fact, DDR memories these days are capable of powering off some their areas, which allows to save power. Of course, when an area of the memory is powered off, its contents are lost, so the kernel needs to ensure that nothing valuable remained on this area of memory. Their kernel modifications allow to describe how the memory is organised (which address ranges are available and can be powered down independently) and introduce some kernel memory allocator changes to reference count those banks of memory. Of course, the next problem is that physical memory is usually highly fragmented, so they detailed how they re-used some of the existing kernel mechanisms to group unmovable pages on one side and movable pages on the other side and that allow to defragment the movable pages. This topic has been worked on since quite a long time in the kernel, as can be found in this LWN article from 2006.

Saving the Power Consumption of the Unused Memory, Loïc Pallardy
Saving the Power Consumption of the Unused Memory, Loïc Pallardy

On my side, I attended the What Android and Embedded Linux Can Learn From Each Other talk. The speaker detailed many of the Android kernel additions and how they could, theoretically, be re-used in non-Android embedded Linux systems. Things like re-using the Binder inter-process communication mechanism, or simple things like the RAM-based Logger mechanism. Unfortunately, none of the speaker’s suggestions were backed by any sort of real experimentation, so those suggestions were mostly speculations. For example, he suggested the possibility of re-using the Android graphics stack on a non-Android system, but most likely this is a very difficult task to achieve and not necessarily worth the effort. At the end of the talk, the speaker suggested that the embedded Linux community and the Android community should talk more to each other, but looking at how Google is driving Android development, it is difficult to see this happening in the near future.

Then, the talk from Hisao Munakata about Close Encounters of the Upstream Resource was an interesting and good summary of the tensions that exist within embedded companies between the product teams (who have deadlines and need the product to work, and don’t want to worry about upstreaming things) and the community teams (who are in relation with the community and try to upstream modifications). He had really nice slides to show the multiple issues that a company faces when it produces major modifications to open-source components such as the Linux kernel, without any effort to upstream them. But he also said that things are improving, and that with Android using fairly recent kernel versions, the embedded Linux system makers are now much closer to mainline versions, which helps in getting changes merged in the official Linux kernel. He advocated that embedded Linux developers should be proficient with git, because it allows to easily track the modifications, find out whether bugs have been fixed in later versions of the Linux kernel, etc. He also quickly presented LTSI, an initiative that offers long-term support around the Linux kernel. He presented it as the way of solving the fragmentation between the vendor BSPs kernel versions, the Android versions, and all other kernel versions that are floating around. However, how those versions will get merged into the official Linux kernel was not really clear.

In the afternoon, Grégory went to the talk Comparing Power Saving Techniques For Multicore ARM Platforms, presented by Vincent Guittot was an other talk presented by a French guy from ST Ericsson. As the one Grégory saw in the morning about power management of memories, this one was also very instructive, well documented and the speaker seemed to really know his topic. He worked the right way on Linux: only very minimal changes inside the kernel, tried to reuse the existing components, provided a git tree available and proposed some improvements on the mailing lists: good job!

Grégory also attended the traditional talk from Tim Bird entitled Status of Embedded Linux. Very pleasant talk (as usual with Tim Bird). It was a very good overview of the state of embedded Linux. If you want to start working on embedded Linux this talk is a must see. Moreover Tim mentioned the valuable work done by Bootlin by recording and sharing the conferences for many years!

The Status of Embedded Linux, Tim Bird
The Status of Embedded Linux, Tim Bird

Later in the day, I attended the talk Passing Time With SPI Framebuffer Driver given by Matt Porter, who now works for Texas Instruments. His talk was feedback from real-life experience developing a driver for a SPI framebuffer controller. Initially, the problem was that a customer had started developing a driver, but that driver violated all the Linux development rules: no usage of the GPIO APIs, no usage of the SPI infrastructure, no usage of the device model, everything was done through a basic character driver directly manipulating the hardware registers. This is something that we also see quite sometimes at Bootlin in the kernel code of some customers: this happens when the code has been written by developers who have only started reading the Linux Devices Driver book, but didn’t go far enough in the Linux code to understand the device model and the principle of code re-usability. So clearly, Matt’s experience resonated with our own experience. So, Matt went on to describe how the driver worked, modifications needed at the board configuration level, the driver itself, its integration in the device model. He also clearly detailed how a SPI framebuffer can work. On a normal framebuffer integrated into the SoC, the framebuffer memory is directly mapped into the application address space so that the application can directly draw pixels on the screen. However, when the framebuffer controller is over SPI, it is clearly not possible to map the framebuffer memory into the application address space. But fortunately, the kernel has a dedicated mechanism for such case: FB deferred I/O. What gets mapped into the application address space is normal kernel memory, but the kernel detects thanks to page faults when a portion of this memory has been changed, and calls the framebuffer driver so that the driver has an opportunity to push these changes over SPI to the framebuffer controller. Of course, this mechanism run at a configurable frequency. The device that was used by Matt Porter was a 1.8 screen available from Ada Fruit, this might also been a good device to use in our future kernel courses, to let participants exercise with driver development.

At the end of the day, I attended the Experiences With Device Tree Support Development For ARM-Based SOC’s by Thomas P. Abraham, from Samsung Electronics, but also from Linaro. It was clearly an excellent presentation about the device tree and how it works. It showed, with lots of code examples, how to compile the device tree source into a device tree blob, how to configure and use U-Boot to get this device tree blob loaded and passed to the kernel, how the board files in the kernel are changed to use the device tree, how device drivers are modified, how the platform data mechanism is changed with the device tree, and more. Definitely a must-see for anyone doing ARM development these days.

My colleague Maxime went to the talk from Paul McKenney about Making RCU Safe For Battery-Powered Devices. Maxime reported that it was an excellent introduction to RCU: Paul introduced very progressively the various issues, so it was possible even for an RCU-newbie to follow that talk. Definitely a presentation I will watch thanks to the video recording!

In the evening, there was the traditional social event of the conference. It took place at the Hiller Aviation Museum, they have lots of strange aircrafts or helicopters, such as a piece of the supersonic Boeing prototype plane, or other bizarre flying devices such as this flying platform.

Android Builders Summit: day 2, and Yocto Developer Day

It’s now Thursday morning here in Redwood City, California, and I didn’t had the time yesterday morning to do a write-up about our second day at the Android Builders Summit. Hopefully the following write-up will give our readers some details about what happened during this day.

This second of Android Builders Summit was co-located with the Yocto Developer Day, and as my colleagues Maxime Ripard and Grégory Clément were attending the two tracks of Android Builders Summit, I decided that I would attend the Yocto Developer Day.

Yocto Developer Day

Yocto is an umbrella project that consists in creating an embedded Linux build system, called Poky and some associated development tools. Poky takes its roots into the OpenEmbedded community: it re-uses the bitbake recipe processor, and a set of recipes for building packages that are now shared between Yocto and OpenEmbedded through the openembedded-core repository. At Bootlin, we are strong contributors to the Buildroot build system, and we use it for many of our customer projects. However, being pushed very strongly by Intel and the Linux Foundation, Yocto is gaining traction, and the fact that Yocto provides stable releases every 6 months now makes it a lot more usable than OpenEmbedded, which had to be checked out through Git, leaving the user with the uncertainty on whether the version (s)he got would actually work or not. And moreover, Buildroot and Yocto are not really competing projects: Buildroot is a simple root filesystem image generator, while Yocto is more a cross-distribution generator, they target projects of different sizes.

I started attending the Yocto Developer Day with a general presentation talk about what Yocto is and why it is necessary. Nothing really new in this talk for someone who already uses embedded Linux build systems and understands the need for such tools. However, the thing that always surprises me is that the Yocto project claims everywhere to solve the fragmentation problem in the embedded Linux build system space (there are too many tools in this area) by creating the tool, and that they envision that in 5 years, everybody will link embedded Linux build with the Yocto project. It’s quite funny because at the moment, they have just created yet another build system 🙂 But it’s true that the project is gaining traction and seems to attract the SoC vendors, which is a good thing because having a standard build system is so much better than having crappy vendor-specific build systems.

Yocto Developer Day: Yocto introduction by Saul Wold from Intel
Yocto Developer Day: Yocto introduction by Saul Wold from Intel

The second talk, by Saul Wold, from Intel, went more into the details on how to use Yocto: what the different components are, how recipes are written, how configuration is defined, what tasks, images, recipes, etc are. I would have liked if the talk went a bit further into the details, but it gave a very good introduction to the Poky build system.

In the afternoon, I attended a hands-on session for new users to Yocto. The room setup was very impressive: about forty high-end PCs provided, each having a development board next to it. The first part of the hands-on session consisted in using Yocto to produce a basic filesystem image which we booted into Qemu. In order to solve the very long first build problem that all OpenEmbedded and Yocto users face, they had pre-built a number of packages and stored them into a shared state directory. Interestingly, the size of the Yocto output directory was about 30 GB, just to build an embedded Linux system with BusyBox and a few minor things. Once this was done, we went ahead in creating our own layer, in order to define our own image and its contents it terms of packages. We used it to add a graphical splashscreen, and I also extended it to include Dropbear into the build. The whole thing went quite well. One thing that worries me is that bitbake and the build process really looks like a black box, and it seems hard to understand what’s going on behind the scenes. With Buildroot, I am used to a very simple build system with which it is very easy to fully understand what’s going on. Here, even the people that give speeches about Yocto or deliver a bit of training, seem to not fully understand what’s going on. This impression is also validated by the complexity of the output directory (where all the build results are). But maybe it’s just a matter of spending some time using it and reading some code, but the fact that people that have been developing/using Yocto for a while still do not really understand its internals is a bit surprising. Or maybe it’s just a wrong impression on my side.

Yocto Developer Day: hands-on session starting
Yocto Developer Day: hands-on session starting

The next part of the hands-on was around the Eclipse integration of Yocto. First with ADT (Application Development Toolkit), which integrates the cross-development thing into Eclipse. Thanks to an agent running into the target, Eclipse is able to push the application binary to the target and start gdbserver on it, and therefore transparently start a debugging session for the user. I am not a big fan of Eclipse (I have been an Emacs user for a huge number of years), but it’s true that for people used to Integrated Development Environments, this ADT thing provides a quite nice experience. Then, we went ahead in trying to use HOB, which integrates into Eclipse the possibility of selecting which packages should be built and integrated into the image. Unfortunately, it seems it didn’t work for anybody (even though we were selecting the package in the GUI, it didn’t appear in the final filesystem image), but that wasn’t a big problem since I don’t really see the point in a tool such as HOB: editing configuration files is something that shouldn’t scare any embedded Linux developer.

Regardless of the contents of the hands-on, I was quite interested by how it was conducted. Instead of having some written lab instructions, and having everyone following, alone, those lab instructions, the instructor was simply demoing the various steps to be done on the video-projector screen, which we simply had to replicate. It makes the session quite interactive, with of course the drawback that everyone needs to progress at the same pace.

All in all, this Yocto Developer Day was interesting, and I hope to find some time soon to experiment further with Yocto.

Android Builders Summit

My colleagues attended multiple talks about Android during this second day of the conference. In the morning, they attended Headless Android, Towards a Standard Audio HAL for Android, Android on eMMC: Optimizing for Performance.

Android Builders Summit: Real-time Android
Android Builders Summit: Real-time Android

In the afternoon, Grégory attended the Real-Time Android talk, which he said, was interesting. It showed that it was possible to integrate the PREEMPT_RT patches together with the Android kernel modifications, and provide a system having real-time capabilities for native (C/C++) applications and still the nice aspect of the Android user interface. During the same slot, Maxime attended the Android Services Black Magic, given by Aleksandar (Saša) Gargenta from Marakana. As usual with the Gargenta brothers, the talk was highly interesting and gave a lot of detailed information about Android services.

Some other thoughts…

At the organization level, the conference organizers should make it clear in the conference program and flyer the location where the slides will be posted. At almost every talk there is someone that asked if and where the slides will be posted, and the speakers are sometimes a bit uncomfortable because there is no clearly identified place to post the slides. In the past years, it was made clear that the slides would be posted on the elinux.org wiki, but this year, things are very unclear. Moreover, it’s even more surprising since speakers are asked to post their slides into their Linux Foundation website account, but those slides are not being made visible. Maybe a good suggestion for the Linux Foundation would be to improve how slides are handled and posted online.

Another thought about the Android Builders Summit is the surprising absence of Google, the developer and maker of Android. Google sponsors the Embedded Linux Conference which takes place right after the Android Builders Summit, but they do not sponsor the Android Builders Summit. There is also no talk from Google developers, and I haven’t seen any Google person in the attendees. It’s even more surprising when we know that the conference takes place in a location about 18 minutes away by car from Google headquarters in Mountain View. Maybe Google doesn’t want to see Android being used in application areas other than phones and tablets?

First day at the Android Builders Summit

Yesterday was the first day at the Android Builders Summit 2012, here in Redwood City, near San Francisco, California. My colleagues Grégory Clément and Maxime Ripard as well as myself are fortunate to attend this conference, and the contents of the first day were really interesting.

Amongst others:

  • A talk from Karim Yaghmour, well-known for having worked on the original version of the Linux Trace Toolkit, on the Adeos patch, as well as for its activity around Android. He delivered a 30 minutes talk about Leveraging Linux’s history in Android, which covered the differences in architecture between a standard embedded Linux system and Android, as well as how to nicely integrate BusyBox or tools like the Linux Trace Toolkit into Android. The presentation was really impressive: in just 30 minutes, Karim covered a huge number of slides, and made several live demonstrations. It is also worth noting that Karim, following the direction that Bootlin has drawn 7 years ago, has decided to release his Android training materials under a Creative Commons BY-SA license.
  • A panel with multiple kernel developers and people involved in Android on how to integrate the specific Android kernel patches into the mainline kernel. Not many new things learned here: the issue with the Android patches is that they add a lot of new userspace-to-kernel APIs, and such code is much much harder to get in mainline than conventional driver or platform code, since such APIs need to be maintained forever. Interestingly, Zach Pfeffer from Linaro pointed out the fact that the major problems with Android integration these days are not due to the kernel patches, but rather to the horrible binary blobs and related drivers that are needed for 3D acceleration ARM SoCs (Systems On a Chip).
    Panel « Android and the Linux Kernel Mainline: Where Are We? »
    Panel « Android and the Linux Kernel Mainline: Where Are We? »
  • A talk from Marko Gargenta on how to customize Android. He explained how to expose a specific Linux kernel driver functionality to Android applications, through a native C library, the JNI mechanism and an Android service, with complete details in terms of source code and build system integration. This presentation, just like last year’s presentation from Marko, was absolutely excellent. A lot of content, very dynamic presentation, a lot of things learned.
  • A talk on how ADB (Android Debugger) works. The contents were really good as well here, with lots of details about the ADB architecture, some tips and tricks about its usage, and more. Unfortunately, the speaker was really not familiar with English, and most of its presentation was spent reading the slides. This is a bit unfortunate because the technical contents was really, really excellent. The slides are available at http://www.slideshare.net/tetsu.koba/adbandroid-debug-bridge-how-it-works.
  • Using Android in safety-critical medical devices. This talk was not about technical issues, but rather about the reason for using Android in medical devices (get those devices connected together and collect some data to learn more about medical practices, their efficiency and cost) and also the legal requirements to get such devices validated by the Food and Drugs Administration in the US. A lot of useful arguments on how to convince managers that Android and Linux in general are usable in safety-critical medical devices.
  • A talk about Over-The-Air updates in Android, which I didn’t attend, but my colleague Maxime Ripard and other attendees gave an excellent feedback about it. It detailed an advanced system for safely upgrading an Android system, using binary diffs and other techniques.
    Customizing Android by Marko Gargenta, Marakana
    Customizing Android by Marko Gargenta, Marakana
  • The talk about Integrating Projects Using Their Own Build System Into the Android Build System had a really promising title and abstract, but unfortunately, the contents were disappointing. The speaker took 25 minutes just to explain how to build BusyBox (outside of any Android context) and then another 20 minutes to explain how to integrate it in the Android build system, on unreadable slides.
  • The talk about Android Device Porting Walkthrough was really great. Benjamin Zores exhausted its time slot with a 1h15 talk instead of the 50 minutes slot allocated, but fortunately, it was the last talk of the day in this session. During this talk, Benjamin gave a huge amount of information and many details about various issues encountered in the process of adapting Android for an Alcatel business VoIP phone (the ones you see in business desks). Issues like filesystem layout, input subsystem configuration, touchscreen configuration, graphics and much much more were covered. Be sure to check out Benjamin slides at http://www.slideshare.net/gxben/android-device-porting-walkthrough.
  • Finally, the day ended with a lightning talk session moderated by Karim Yaghmour. Lightning talks are really nice, because in less than 5 minutes, you quickly hear about a project or an idea. When the speaker is not good or the topic uninteresting, you know that after 5 minutes, you’ll hear someone else speaking about a different topic. The lightning talk on the integration of GStreamer in Android was really interesting, as was the lightning talk from Karim about its CyborgStack initiative, which creates an upstream Android source to integrate all the Android modifications that will never be mainlined by Google. See Karim slides at http://www.cyborgstack.org/sites/default/files/cyborgstack-120213.pdf for details.

And now, it’s time for breakfast, before the conferences of the second day of this Android Builders Summit.

Bootlin at the Android Builders Summit and the Embedded Linux Conference: one talk and video recording

A good part of the Bootlin team will be in San Francisco (actually, not in San Francisco, but in the Bay Area) from February, 13th to 17th for the Android Builders Summit and the Embedded Linux Conference.

Android Builders Summit 2012
Android Builders Summit 2012

The Android Builders Summit is the second edition of this conference dedicated to Android system development (and not application development). Compared to last year, the conference has been extended to three parallel tracks during two days. There are many talks about Android customization, Android internals, Android porting, usage of Android in specific markets (medical devices, vehicle infotainment), etc. A lot of useful talks for developers working at the Android system level.

Embedded Linux Conference 2012
Embedded Linux Conference 2012

The Embedded Linux Conference is now a well-established conference. Again for this 2012 edition, there will be three parallel tracks during three days. There will be talks about many, many topics: performance and optimization, power management, build systems, drivers for various types of devices, multimedia, ARM kernel support and much more.

I will be giving a talk about Buildroot: A Nice, Simple and Efficient Embedded Linux Build System on the second day of the conference. The aim of the talk is to give a status on where Buildroot is, three years after a maintainer was chosen and a big clean up work was started. The project has changed a lot compared to its state three years ago, so I thought it would be nice to make a status on where Buildroot and where it is going.

With my colleagues Grégory Clément and Maxime Ripard, we will also record all the talks from the Embedded Linux Conference in order to put the videos online, freely available, after the conference, as we have done for many past conferences.

We hope to meet you in San Francisco for the Android Builders Summit and the Embedded Linux Conference!

Bootlin at FOSDEM: two talks and video recording

I'm going to FOSDEMAs usual, Bootlin will again be present at the FOSDEM conference in Brussels, on February, 4th and February 5th. We will of course mostly be attending the Embedded DevRoom, with multiple talks around development in the embedded space.

We will also be giving two talks this year:

  • My colleague Maxime Ripard will be giving a talk about IIO, a new subsystem for I/O devices. In short, IIO is a new subsystem in the kernel to write drivers for devices like Analog-to-Digital converters. Maxime has worked on a driver inside the IIO subsystem for the internal ADCs of the AT91 processors from Atmel, and will base his talk mostly on the experience developing this driver. This talk will take place on Saturday, 12:00 AM to 1:00 PM in the Lameere room.
  • I will be giving a talk on Using Qt for non-graphical applications. It is a talk that has already been given at the Embedded Linux Conference Europe, but the audience of FOSDEM and ELCE being quite different, we have chosen to propose it for FOSDEM as well, and it got accepted. This talk will take place on Sunday, 1:00 PM to 2:00 PM in the Lameere room.

There are also other talks that are worth noting: a SoC power management talk from Jean Pihet who works on OMAP power management support in the Linux kernel, a talk about OpenCores and OpenRISC, a talk about Safe Upgrade of Embedded Systems by Arnout Vandecappelle, who contributes a lot to Buildroot, and also other talks about OpenWRT, Yocto, licensing issues in Android, the EFL libraries, and more.

We will also be carrying our camcorder to video record those talks. We are trying to see with the FOSDEM organization team if it possible to record the audio directly from the room sound systems in order to provide better audio quality in our videos.

If you happen to be at FOSDEM, we’d be very happy to meet you!