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 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
  • 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
  • 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 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!

Announcing our “Android System Development” training

Android RobotFor multiple years, Bootlin has provided two typical training courses for embedded Linux developers: an Embedded Linux system development course that focuses on the basics for embedded Linux development (bootloader and kernel configuration, compiling and usage, system integration and build systems, cross-compiling, filesystems, application development and debugging, etc.) and an embedded Linux kernel and driver development course that focuses on kernel and driver development (kernel APIs for drivers, character drivers, device model, power management, kernel porting, etc.). In total, we have given dozens of editions of these sessions in multiple locations all around the world. We have kept our commitment to release all the training materials under a free license (the Creative Commons CC-BY-SA license), and they are therefore freely accessible for anyone at /docs/.

We are now announcing a new course, called Android System Development. It is a four day training session that targets engineers who need to develop embedded systems with Google Android.

Through theory and practical labs, the course makes you familiar with compiling and booting Android, with adapting Android to support a new embedded board (assuming that it is already supported by the Linux kernel), and with building a real system through accessing specific hardware, customizing the filesystem and using debugging techniques. See the complete agenda. The training materials for this session will also be made available under the same Creative Commons CC-BY-SA license.

If you are interested in this training session, you can:

  • Join the public session organized in Toulouse, France, on June 11-14, 2012.
  • Order an on-site training session to be held at your location. See registration details.

This training course will be given by our engineer Maxime Ripard who has gained Android experience by working at Archos on Android tablets, by making Android work on multiple TI OMAP3 based platforms and also by participating to the Android Builders Summit conference.

Do not hesitate to contact us for further details about this new training course.

Videos of Android Builders Summit 2011

Android LogoJust after the Embedded Linux Conference 2011, the first edition of the Android Builders Conference took place in San Francisco, on April 13th and April 14th 2011. This is the first, and to date, probably the first, conference entirely dedicated to Android low-level components and on how Android systems are built and modified. The number of resources, documentation and conferences on Android application development is already huge, but the amount of system-level information about Android is still relatively limited. This conference comes to fill in this gap, allowing engineers working on Android-based systems to share their experience. With a single track of talks for the first half-day, and two tracks for the second full day, it was a very nice first edition, and the co-location with the Embedded Linux Conference was well-appreciated. Interestingly enough, no talks were given by Google engineers, despite the fact that they are the primary designers and developers of the Android system.

Just as we did for the Embedded Linux Conference a few days ago, we are also publishing below the videos of all talks given during this Android Builders Summit. Of all the presentations, the ones we found the most interesting are certainly:

  • Karim Yaghmour’s talk about « Android Internals » and «Porting Android to new hardware»
  • Aleksander “Sasa” Gargenta’s talk «A walk through the Android stack». Unfortunately, the speaker had way too much contents for the one hour slot, but the content presented was very, very interesting.
  • Mark Brown’s talk «Linux audio for smartphones»

Mike WosterVideo capture
Linux Foundation
Android Builders Summit Introduction
Video (2 minutes):
full HD (31M), 450×800 (11M)

Christy WyattVideo capture
Motorola: innovation rising
Video (36 minutes):
full HD (454M), 450×800 (142M)

Mark CharleboisVideo capture
Qualcomm Innovation Center
From the alliance to the evolution: the history and future of Android innovation
Video (26 minutes):
full HD (332M), 450×800 (103M)

Greg BurnsVideo capture
AllJoyn and the new era of peer-to-peer-technology
Video (55 minutes):
full HD (680M), 450×800 (209M)

Mark BrownVideo capture
Wolfson Micro
Linux audio for smartphones
Video (46 minutes):
full HD (560M), 450×800 (173M)

Karim YaghmourVideo capture
Android Internals
Video (58 minutes):
full HD (793M), 450×800 (245M)

Mark GrossVideo capture
Device provisioning anad over the air updates for Android-2011
Video (48 minutes):
full HD (847M), 450×800 (214M)

Peter VescusoVideo capture
Black Duck Software
Managing Android and the complexity inside
Video (35 minutes):
full HD (375M), 450×800 (121M)

Hansung ChunVideo capture
I/O performance improvement, using ext2 in Android-2011
Video (44 minutes):
full HD (915M), 450×800 (210M)

Magnus BäckVideo capture
Sony Ericsson
Using the Debian package manager to assemble Android-based phone software systems
Video (45 minutes):
full HD (357M), 450×800 (134M)

Tim BirdVideo capture
Sony Network Entertainment
Trying to improve Android boot time with readahead
Video (38 minutes):
full HD (833M), 450×800 (194M)

Bruce BeareVideo capture
Living with Gerrit
Video (42 minutes):
full HD (404M), 450×800 (137M)

Karim YaghmourVideo capture
Porting Android to new hardware
Video (43 minutes):
full HD (822M), 450×800 (209M)

Marko GargentaVideo capture
Beyond the phone
Video (44 minutes):
full HD (682M), 450×800 (193M)

Neil TrevettVideo capture
Open API standards as a foundation for Android innovation
Video (42 minutes):
full HD (523M), 450×800 (173M)

Vitaly Wool, presented by Mark GrossVideo capture
Sony Ericsson
WiFi and Android: powersave saga
Video (31 minutes):
full HD (544M), 450×800 (136M)

Aleksander “Sasa” GargentaVideo capture
A walk through the Android stack
Video (60 minutes):
full HD (689M), 450×800 (234M)

Armijn HemelVideo capture
Licensing pitfalls in Android and how to avoid them
Video (44 minutes):
full HD (662M), 450×800 (183M)

Tim BirdVideo capture
Sony Network Entertainment
Android System Programming Tips and Tricks
Video (42 minutes):
full HD (459M), 450×800 (153M)

Creative commonsIn agreement with the speakers, these videos are released under the terms of the Creative Commons Attribution-ShareAlike 3.0 license.

Bootlin at the Embedded Linux Conference and Android Builders Summit

In just two weeks from now, the Embedded Linux Conference will start in San Francisco, followed by the Android Builders Summit, at the usual Hotel Kabuki location, where the conference is taking place for the third consecutive year.

Embedded Linux Conference 2011

The program of the Embedded Linux Conference has been announced recently, and as usual, features a wide set of technical embedded Linux talks:

  • Filesystem/storage: Power Fail Safe FAT File System, Optimizations For Cheap Flash Media, from Arnd Bergmann, who has also recently published a very interesting article on the same topic.
  • Power management: Faster Resume For More Energy Savings on MeeGo, Powerdebug(ging): A Linaro Perspective, How to Power Tune a Device Running on a Linux Kernel for Better Suspend Battery Life, The Evolution of Tracing and Profiling for Power Management and Accelerators, Runtime PM: Upstream I/O Device Power Management
  • Real-time: Solving Real-Time Scheduling Problems with RT_PREEMPT and Deadline-Based Scheduler, Real-time Audio on Embedded Devices, Identifying Embedded Real-Time Latency Issues: I-Cache and Locks
  • Build system, with a huge number of Yocto-related talks, but no other build systems represented: State of OpenEmbedded Internal Toolchain and SDKs, Yocto Project: Practical Kernel Development Tutorial, Building Custom Embedded Images with Yocto, The Yocto Project and its Application Development Toolkit (ADT) – The Answer to Effective Embedded Application Development, Yocto Project Community BoFs, Delivering Predictability: The Yocto Project Autobuilder, Automated Sanity Testing, License Collection, and Build Statistics Tracking
  • Multimedia: Fun with QML and JavaScript, Integrating a Hardware Video Codec into Android Stagefright using OpenMAX IL, Media Controller Framework (MCF) For OMAP2+ Display Subsystem, Video4linux: Progress, New videobuf2 Framework and the Media Controller, Bringing up HDMI Display for OMAP4 Panda Board – Design, Challenges and Lessons Learned, Linux Graphics Meets the ARM Ecosystem
  • FPGA: Dynamic Co-simulation of FPGA-based Linux Systems-on-Chip, A High Performance Interface Between the OMAP3 and an FPGA
  • Networking: What Embedded Linux Developers Should Know About IPv6, Zigbee Networking & Linux
  • Debugging: Kernel Shark Tutorial and Tools and Techniques for Debugging Embedded Systems
  • Optimization: Snapshot Booting on Embedded Linux, ARM Neon Instruction Set and Why You Should Care, Controlling Memory Footprint at All Layers: Linux Kernel, Applications, Libraries and Toolchain, High-Performance Computing using GPUs, What Are and How to Find a Program’s Unused DSOs
  • Low-level: Board Bringup: Open Source Hardware and Software Tools, Working with HardIRQs: Life Beyond Static IRQ Assignments, Genie in the Bottle: Linux Drivers for the AM1808 PRU
  • And many other talks on various topics: LLVM, Clang and Embedded Linux Systems, Linaro: A Year of Change, Control, Recover and Debug Your Embedded Product with PCD, Developer’s Diary: Helping the Process, High-Level Web Interface to Low-Level Linux I/O on the Beagleboard, Linaro Automated Validation on ARM, Crowd Sourcing and Protecting the Open Source Community, Android for Servers?, Hot Multi-OS Switch: How to run Ubuntu, ChromiumOS, Android at the Same Time on an Embedded Device.

This edition will be the first one organized since the merge between the CE Linux Forum into the Linux Foundation, and will therefore be a great opportunity to see if this merge had any impact on the technical quality of the conference.

My colleagues Maxime Ripard (who joined Bootlin just a week ago) and Gregory Clement as well as myself will be present at the Embedded Linux Conference and the Android Builders Summit, and we will as usual record all talks of both of these conferences and will put them online, as we have done recently for the talks that took place during the Embedded Linux Conference Europe 2010 in Cambridge. Do not hesitate to meet us in San Francisco!

ELC-E 2010 tutorial videos

Videos from the embedded Linux and Android tutorials at ELC-E 2010, by Chris Simmonds

As releasing ELC-E 2010 videos, here are recordings of the embedded Linux and Android tutorials, performed by Chris Simmonds on October 26, 2010.

Chris SimmondsVideo capture
The Embedded Linux Quick Start Guide – Part 1
Video (52 minutes, 397M)
Chris SimmondsVideo capture
The Embedded Linux Quick Start Guide – Part 2
Video (79 minutes, 660M)
Chris SimmondsVideo capture
The Embedded Linux Quick Start Guide – Part 3
Video (67 minutes, 501M)
Chris SimmondsVideo capture
What else can you do with Android? – Part 1
Video (49 minutes, 432M)
Chris SimmondsVideo capture
What else can you do with Android? – Part 2
Video (31 minutes, 293M)
Chris SimmondsVideo capture
What else can you do with Android? – Part 3
Video (59 minutes, 545M)

Linux 2.6.33 features for embedded systems

Interesting features for embedded Linux system developers

Penguin workerLinux 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 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.