Category: Technical

Free Android training materials

Android robotAfter months of preparation, and after completing our first Android system development training session, we are proud to release our complete training materials under the Creative Commons Attribution – Share Alike 3.0 license.

Our course targets engineers who need to develop embedded systems with Google Android, customizing Android to support specific hardware and product requirements.

Here are the main topics that we cover:

  • Introduction to Android
  • Android source code and compiling
  • Linux kernel, configuration, compiling and booting
  • Bootloaders for Android
  • Android changes to the Linux kernel
  • Supporting new hardware
  • Development and debugging with ADB
  • Android’s build system
  • The Android filesystem
  • Android native layer and calling a C program from Android
  • Android framework and applications
  • Application development
  • The apk standard
  • System customization
  • Advise and resources

See the detailed agenda.

Just like the materials for our Embedded Linux system development and Embedded Linux kernel and driver development courses, this new courseware is meant to be be a useful resource for product developers around the world. It could also be used by engineers with sufficient Android experience to train their colleagues without having to spend months preparing slides and practical labs as we did.

Devkit8000 board from EmbestPractical labs are conducted on the Devkit8000 embedded board from Embest, with a TI OMAP3 CPU and an LCD touchscreen. As we use Linaro Android in our labs, it should be relatively easy to make these labs on other development boards with a Linaro supported CPU (TI OMAP, Freescale i.MX53 and i.MX6, ST Ericsson Nova and Samsung Exynos).

LaTeX sources for these materials are available on Bootlin’spublic git server.

To build these documents from source, you may need to install several packages (thanks to Huy, Bui Quang, for contributing the package list):

sudo apt-get install git-core inkscape texlive-latex-base \
texlive-latex-extra texlive-font-utils dia python-pygments \
texlive-fonts-recommended

You can then build the latest version as follows:

git clone git://github.com/bootlin/training-materials.git
cd training-materials
make full-android-labs.pdf
make full-android-slides.pdf

The LaTeX format and the git repository make it easy to identify changes made since the last time you accessed the materials. We even have a training-materials-updates mailing list to receive notifications for updates to all our training materials. Compared to the Open Document Format that we used in the past, this should also make it considerably simpler to translate these documents and keep translations up to date.

As usual, comments, suggestions and translations are welcome. You can write to the feedback address available on our contact page.

Bootlin at the Libre Software Meeting

In a previous post, we detailed all the talks of the Embedded Systems and Open Hardware track of the Libre Software Meeting, taking place in Geneva in early July.

Bootlin will have a quite important presence at this event, with three talks and one tutorial given by Bootlin engineers. You’ll find below the descriptions of the talks given by Bootlin. Both my colleague Maxime Ripard and myself will be present at Libre Software Meeting, and we will be happy to meet you there to discuss Embedded Linux and Android topics!

A look through the Android Stack

Android has established itself in the past years as a major player in the mobile market, outperforming any other mobile systems.

To do so, Google relied both on well established open-source components, such as the Linux Kernel, and munching them together in a brand new userspace environment. This talk will detail the most important components of Android userspace and the interactions between them that allow developers to face a consistent API for their applications.

This talk will be given on Tuesday 9th July 2012, at 14:00, by Maxime Ripard, embedded Linux and Android engineer at Bootlin. Maxime is also teaching our newest training course on Android system development.

Buildroot: a nice, simple and efficient embedded Linux build system

Started in late 2001 by uClibc developers, Buildroot has grown over its 10 years history from a testing tool for the uClibc C library to a complete, vendor-neutral, embedded Linux build system. Until early 2009, the project was mostly unmaintained and the quality slowly decreased, frustrating many Buildroot users. Fortunately, since early 2009, Peter Korsgaard took over the maintainership of Buildroot, and the project has considerably evolved since then: stable releases are published every three months, the user and developer community has grown significantly, the existing features have been cleaned up, many other new features have been added, the project is no longer uClibc-specific and the quality has been vastly improved. Buildroot now offers a nice, simple and efficient mechanism to build small to medium sized embedded Linux systems, such as the ones found in many industrial systems or highly dedicated systems. Many users are amazed about how easy it is to get started with Buildroot, especially compared to other build systems. This presentation will show how Buildroot can be used to build embedded Linux systems, highlighting the new features and improvements made over the last few years, and detailing how the simplicity of Buildroot allows you to focus on developing the applications for your system. A quick overview of the future Buildroot developments will also be provided.

This talk will take place on Wednesday 10th July at 17:00 and will be given by Thomas Petazzoni, embedded Linux engineer at Bootlin, and long time Buildroot contributor.

Linux kernel on ARM: consolidation work

In Spring 2011, Linus Torvalds asked the ARM Linux maintainers to clean up the contents of arch/arm/ in the Linux kernel code by doing more consolidation between ARM sub-architectures.

More than a year later, a lot of work has been accomplished in this area, especially thanks to the introduction of the device tree for the ARM architecture, the pinctrl subsystem and the clock framework into the Linux kernel.

Through this talk, we will present the challenges the ARM architecture creates in terms of Linux kernel support, and then describe from a technical point of view how the device tree, the pinctrl subsystem and the clock subsystem work and how they can improve the consolidation between different ARM sub-architectures.

The talk will be designed to be accessible to an audience having only a moderate knowledge of kernel programming and internals, and will therefore provide enough context for such audience to understand the issues that those different mechanisms are striving to solve.

This talk will take place on Thursday 11th July at 10:00 and will be given by Thomas Petazzoni, embedded Linux engineer at Bootlin.

Tutorial on using Buildroot, a nice, simple and efficient embedded Linux build system

Started in late 2001 by uClibc developers, Buildroot has grown over its 10 years history from a testing tool for the uClibc C library to a complete, vendor-neutral, embedded Linux build system. Until early 2009, the project was mostly unmaintained and the quality slowly decreased, frustrating many Buildroot users. Fortunately, since early 2009, Peter Korsgaard took over the maintainership of Buildroot, and the project has considerably evolved since then: stable releases are published every three months, the user and developer community has grown significantly, the existing features have been cleaned up, many other new features have been added, the project is no longer uClibc-specific and the quality has been vastly improved. Buildroot now offers a nice, simple and efficient mechanism to build small to medium sized embedded Linux systems, such as the ones found in many industrial systems or highly dedicated systems. Many users are amazed about how easy it is to get started with Buildroot, especially compared to other build systems.

This workshop follows the Buildroot presentation proposed in the same topic. During one half-day participants will be introduced on how to efficiently use Buildroot for their own projects:

  • Basic usage of Buildroot: generate the first system, boot it on a hardware platform
  • Add packages to Buildroot
  • Customize Buildroot for real-life projects: how to integrate project specific patches, configuration and customization

Participants are invited to come with their own laptop, installed with a sufficiently recent GNU/Linux distribution. Participants are recommended to attend the Buildroot talk by the same speaker before attending the workshop, as the talk will give an overall introduction on Buildroot.

This tutorial will take place on Thursday 11th July from 14:00 to 17:00 and will be given by Thomas Petazzoni, embedded Linux engineer at Bootlin, and long time Buildroot contributor.

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!

Report on extensive real-time Linux benchmarks on AT91

The real time page I wrote for Atmel was finally released on the Linux4Sam Atmel Wiki. The purpose of this page was to help new comers to use real time features with Atmel CPUs and to present the state of the real time support.

Here are some figures associated to this work:

  • On this page I present the results of more than 300 hours of benchmarks!
  • During the setup and the tuning tests ran for more than 600 hours.
  • Analysis and formatting took a few dozen hours of work.
  • The benchmarks have been run on 3 boards, 3 flavors of Linux (vanilla, PREEMPT-RT patches, Xenomai co-kernel approach), and 2 kinds of tests (timer-based and GPIO-based)

    • Experiment with Yocto

    I recently had the opportunity to use Yocto. I already practiced quite a lot with OpenEmbedded before. You can see Yocto as a project derived from OpenEmbedded even it is a bit more than that.

    In fact, Yocto is made of Poky (a build system based on OpenEmbedded), a few added build tools (swabber, pseudo, etc.), as well as a set of meta data allowing to create embedded distributions for a number of targets.

    The strength but also the weakness of OpenEmbedded is that it a very flexible build system. It can make production root filesystems, but also a complete distribution with its ready to use package repository, and this for multiple hardware platforms. It makes it a difficult system to get started and get efficient with. Even two years ago, the OpenEmbedded documentation contributed to making it difficult to get started. Indeed, OpenEmbedded did supply some documentation, but which only started to make sense once you start mastering it. This is quite a paradox for a piece of documentation. It lacked the elements allowing developers to understand its operation well.

    With Yocto, I was pleased to realize that substantial progress had been made on this side. The project comes with documentation that is much more exhaustive and above all much more accessible for beginners. Getting started with it is still not completely straightforward, but this time, this is rather because of the complexity and the rich features of the tool.

    In a few hours, I managed to develop a minimalistic BSP (Board Support Package) for a given board (in this case a AT91SAM9G20-EK). The concept of layer allows to have a configuration layer specific to a given piece of hardware. You can even support multiple hardware platforms at once and add specific packages. A layer is indeed just a set of packages and configurations (or configuration overrides). The BSP is just a layer specific to one or several pieces of hardware.

    As you can see, even to support a simple embedded board, there is already a number of concepts to deal with. There are also multiple ways of achieving the same result but which will be easier or more difficult to maintain. The concept of “BSP” for Yocto is therefore a kind of guideline to allow the Yocto community to have a common point of reference. I will try to illustrate the use of a BSP on the AT91SAMG20-EK board here and/or on my Google+ page.

    Another significant progress is optimizing build time for a “minimalistic” target, which went down from more than three hours to just over one hour now. It remains a long time for a very simple target.

    To build a filesystem image with only a few components, Buildroot remains much more appropriate. For systems that require a great number of components, more advanced functionality is then often needed, such as managing a package repository and supporting multiple hardware platforms at once for example. In this case, Yocto remains the best (the only?) option, all the more as this project addresses the traditional weaknesses of OpenEmbedded.

    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)

    A new tool to ease kernel maintainer life

    When you are involved in mainlining or maintaining some kernel code, a non negligible part of your time is spent checking patches or patchsets themselves . It is not the most interesting part but it is truly necessary to help merging in kernel code, or to make sure you don’t break anything, for example building with an incompatible configuration.

    Aiaiai developed by Artem Bityutskiy is a tool to do most of this task for you! It uses other checking tools and scripts such as sparse, coccinelle and checkpatch.pl, and comes with its own set of tools and scripts. I don’t know what does “aiaiai” stands for, but in French it sounds like “Ouch Ouch Ouch”, the sound you could make if you forget to use this tool 😉

    PS: On my G+ post, Yegor Yefremov pointed that “aiaiai” means something like “tsk tsk!” (shame on you!) in Russian.

    Android gdbclient command

    Before you even start building Android, Google’s instructions tell you to source the build/envsetup.sh shell script.

    This script exports a number of environment variables (that’s why you have to source it), mostly setting the PATH to your different toolchains and to your output directories.

    It also defines a number of shell functions. Among them some functions are advertised, like the well-know lunch, that is used to configure to some extent the build system, or the grepping functions, but some are not, like pid, which uses adb to get the PID of a process running on the device.

    Among the latter, one seems pretty useful: gdbclient. What gdbclient does is obviously gdb related but in fact it does more than that.

    First, you run it by doing gdbclient <binary>:<port> <process_name>

    Then it sets up adb with the forward command so that you use it as a transport layer to your device, while it appears as (in that case) opened TCP sockets both on your machine and on the device.

    Then, it attaches a gdbserver to the process you gave as the third argument on the device.

    Finally, it launches your cross-gdb on your workstation, loads the debugging symbols from the file passed as first argument, and sets up a remote debugging session. All of that through USB!

    This is definitely useful, and I can’t say why Google doesn’t advertise it more, but hey, it’s there!

    How to boot an uncompressed Linux kernel on ARM

    This is a quick post to share my experience booting uncompressed Linux kernel images, during the benchmarks of kernel compression options, and no compression at all was one of these options.

    It is sometimes useful to boot a kernel image with no compression. Though the kernel image is bigger, and takes more time to copy from storage to RAM, the kernel image no longer has to be decompressed to RAM. This is useful for systems with a very slow CPU, or very little RAM to store both the compressed and uncompressed images during the boot phase. The typical case is booting CPUs emulated by FPGA, during processor development, before the final silicon is out. For example, I saw a Cortex A15 chip boot at 11 MHz during Linaro Connect Q2.11 in Budapest. At this clock frequency, booting a kernel image with no compression saves several minutes of boot time, reducing development and test time. Note that with such hardware emulators, copying the kernel image to RAM is cheap, as it is done by the emulator from a file given by the user, before starting to emulate the system.

    Building a kernel image with no compression on ARM is easy, but only once you know where the uncompressed image is and what to do! For people who have never done that before, I’m sharing quick instructions here.

    To generate your uncompressed kernel image, all you have to do is run the usual make command. The file that you need is arch/arm/boot/Image.

    Depending on the bootloader that you use, this could be sufficient. However, if you use U-boot, you still need to put this image in a uImage container, to let U-boot know about details such as how big the image is, what its entry point is, whether it is compressed or not… The problem is you can’t run make uImage any more to produce this container. That’s because Linux on ARM has no configuration option to keep the kernel uncompressed, and the uImage file would contain a compressed kernel.

    Therefore, you have to create the uImage by invoking the mkimage command manually. To do this without having to guess the right mkimage parameters, I recommend to run make V=1 uImage once:

    $ make V=1 uImage
...
  Kernel: arch/arm/boot/zImage is ready
  /bin/bash /home/mike/linux/scripts/mkuboot.sh -A arm -O linux -T kernel -C none -a 0x80008000 -e 0x80008000 -n 'Linux-3.3.0-rc6-00164-g4f262ac' -d arch/arm/boot/zImage arch/arm/boot/uImage
Image Name:   Linux-3.3.0-rc6-00164-g4f262ac
Created:      Thu Mar  8 13:54:00 2012
Image Type:   ARM Linux Kernel Image (uncompressed)
Data Size:    3351272 Bytes = 3272.73 kB = 3.20 MB
Load Address: 80008000
Entry Point:  80008000
  Image arch/arm/boot/uImage is ready

    Don’t be surprised if the above message says that the kernel is uncompressed (corresponding to -C none). If we told U-boot that the image is already compressed, it would take care of uncompressing it to RAM before starting the kernel image.

    Now, you know what mkimage command you need to run. Just invoke this command on the Image file instead of zImage (you can directly replace mkuboot.sh by mkimage):

    $ mkimage -A arm -O linux -T kernel -C none -a 0x80008000 -e 0x80008000 -n 'Linux-3.3.0-rc6-00164-g4f262ac' -d arch/arm/boot/Image arch/arm/boot/uImage
Image Name:   Linux-3.3.0-rc6-00164-g4f262ac
Created:      Thu Mar  8 14:02:27 2012
Image Type:   ARM Linux Kernel Image (uncompressed)
Data Size:    6958068 Bytes = 6794.99 kB = 6.64 MB
Load Address: 80008000
Entry Point:  80008000

    Now, you can use your uImage file as usual.