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!

Buildroot 2011.02 released, with many interesting updates and commercial support!

Buildroot logoAs usual, the latest Buildroot version has been released just in time on the last day of the month: Buildroot 2011.02 is available for download!

This release of the increasingly popular embedded Linux build system provides new interesting features and updates:

  • Support of external toolchains has been improved with support for toolchain profiles. Those are predefined configurations for well-known toolchains such as the CodeSourcery ones for ARM, PowerPC, MIPS and SuperH. Buildroot is now capable of automatically downloading and installing those external toolchains, which is much easier than downloading them manually. It’s now easy to provide users with Buildroot configurations that use well known toolchains, without requiring them to pre-install anything specific.
  • Support for board configurations has been completely rewritten and largely simplified. All board-specific Makefile and configuration options have been removed, and instead, each board is represented by a single, simple (less than 20 lines) defconfig file, in the configs/ directory. In addition to the existing configuration, we have added support for the Mini2440 platform but also for many Qemu emulated platforms: Qemu ARM Versatile, Qemu MIPSel Malta, Qemu PowerPC G3 Beige, Qemu SH4 r2d and Qemu x86. Those configurations allow to easily produce a known-to-work system for the Qemu emulator, making Buildroot even easier to start working on your embedded Linux system. See the documentation for more details on how to add your own board support.
  • Support for the Blackfin architecture has been added, thanks to Mike Frysinger. This support came along with a lot of fixes to make Buildroot work better for non-MMU architectures, since Blackfin is the first actively supported non-MMU architecture in Buildroot. There will certainly be further improvements to support non-MMU architectures, and hopefully additional non-MMU platforms will be added. For those platforms, Buildroot is generally a very good embedded Linux build system, as those architectures are typically used for small to medium sized systems, with a relatively limited number of components.
  • The Crosstool-NG back-end has been improved and extended to support more Buildroot options, and has been upgraded to a newer Crosstool-NG version. This back-end is the third mode for Buildroot toolchain: it allows Buildroot to use Crosstool-NG as the toolchain generator.
  • Ccache support has been reworked and it now works properly. Since Buildroot often requires complete rebuilds from scratch, having the ccache compiler cache is very nice. On my laptop, compiling from scratch a sample Buildroot system was taking 5 minutes and 29 seconds without ccache, and now only takes 3 minutes and 40 seconds with ccache enabled and the cache already filled by a previous build.
  • A new CMake infrastructure has been added for packages, next to the existing generic and autotools infrastructure. For the moment, only two packages are using the infrastructure (cdrkit and libcuefile), but CMake is an increasingly popular build system and we will definitely see more packages using it in the future. Moreover, Buildroot generates a CMake toolchain file that describes the toolchain used by Buildroot, and which makes it very easy to cross-compile external libraries/applications for the Buildroot system using cmake -DCMAKE_TOOLCHAIN_FILE=/path/to/buildroot/output/toolchainfile.cmake.
  • A very nice cleanup job of the internal toolchain build process has been started by Gustavo Zacarias. The build process of binutils, gmp, mpfr and mpc has been migrated to proper packages, and this will also be done for gcc and gdb in the future.
  • As preliminary steps towards the generation of a standalone SDK from Buildroot, two important changes have been made. First, the staging directory is now inside $(O)/host/usr/PLATFORM-TUPLE/sysroot/, but a symbolic link from $(O)/staging has been kept for compatibility. This change will allow the $(O)/host directory to be the standalone SDK in the future. The second change is on pkg-config: its configuration has been adjusted so that it behaves properly to compile target packages without needing any environment variables or options. It makes the Buildroot pkg-config much easier to use to compile external applications.
  • The Python package has been upgraded to the latest Python version, 2.7.1. This was needed since a long time, since the version of Python we had in Buildroot was only 2.4. Moreover, the package has been completely rewritten, with more options, and has been tested on several platforms. Two external Python modules, python-mad and python-serial have also been added as packages, to show how such modules can be integrated into Buildroot.
  • A set of packages to add support in GStreamer for the TI DSP codecs has been added: gst-dsp, gst-omapfb, tidsp-binaries, dsp-tools, thanks to Felipe Contreras.
  • We have a bunch of new packages as well: mpd, the Music Player Daemon with many audio codecs and libraries, the dhrystone and whetstone benchmarks and other tools such as xmlstarlet, fbgrab, irda-utils, lsuio, etc.
  • Many other packages have been upgraded or fixed, and the results of our random configuration builds are much, much better than they were in the past.

As a Free Electrons engineer, I have again contributed significantly to this release: Peter Korsgaard, the Buildroot maintainer, has done 171 commits, Gustavo Zacarias has done 119 commits and I have done 103 commits. The next committer is Mike Frysinger (for the great Blackfin support) with 22 commits.

It is with this great Buildroot knowledge and experience that Free Electrons has launched a few weeks ago an official offering of Buildroot commercial support. If you are using Buildroot for your embedded product, or want the buyers of your hardware platform to have a simple but efficient embedded Linux build system and you need help, development or consulting, do not hesitate to contact us.

Buildroot 2010.11 release and roadmap

Buildroot logoThe 2010.11 release of Buildroot has been published on November, 30th. Buildroot is a tool that eases the process of building an embedded Linux system: cross-compiling toolchain, root filesystem with dozens or hundreds of libraries and applications, bootloader and kernel.

Release 2010.11

Releases are made every three months, and the latest 2010.11 release has a number of improvements :

  • Experimental crosstool-NG back-end for handling the toolchain. Before, Buildroot could either compile a toolchain for you, or use an already existing external toolchain. However, the internal Buildroot process for building a toolchain is limited to uClibc and its maintenance is a duplication of the work done by the Crosstool-NG community. While this back-end is only experimental at the moment, the intention is to make it the default back-end in some future release, if everything works fine. Thanks to Yann E. Morin for implementing this back-end, and making related changes to Crosstool-NG.
  • The Kconfig infrastructure has been updated to the one of 2.6.36 and has been cleaned up (we now have a nice quilt patch series). This brings savedefconfig (for minimal Buildroot configurations) and nconfig support. We now also create a convenience Makefile wrapper in the output directory for out-of-tree builds, like the kernel has. So once you have done a first make O=/some/path menuconfig, you can go into /some/path and directly use make something without having to specify the output directory.
  • Old-style package hooks (*_HOOK_POST_*) have been removed. This was just a clean up process, because we have a more modern way of allowing packages to hook specific commands at various steps of the build process.
  • Download handling has been reworked and support for git/svn downloads was added, so that packages only available through version control systems can be added easily in Buildroot. The make source (to download all needed tarballs and files so that the build can be done completely offline) and make external-deps (to show all files that would need to be downloaded) commands have been improved to fix several issues
  • On the architecture side, support for ARM Cortex A9 and Sparc LEON variants was added. Support for Alpha, Cris, IA64 and Sparc64 (deprecated in 2010.08) was removed.
  • We also added a few more packages: argp-standalone, gdk-pixbuf, gpsd, gst-ffmpeg, libmpeg2, kbd, librsvg, nuttcp, rng-tools, rrdtool and xz. And removed some deprecated packages: dillo, libglib12, libgtk12, microwin and pcmcia.
  • Many, many packages have been updated. In particular, the Gtk+ library has been updated from 2.12 to 2.20, keeping the DirectFB support functional thanks to the work of Lionel Landwerlin (the DirectFB support in Gtk+ was broken since 2.12). So, finally, this brings us a recent and fresh Gtk+ library in Buildroot.
  • Many packages were converted to the autotargets or gentargets infrastructures (that we use to describe how a particular package should be downloaded, extracted, configured, built and installed), in particular thanks to the work of Martin Banky.

I have again contributed quite a bit to this release, but not as much as I wanted to. Here are the numbers:

git shortlog -s -n 2010.08..
   168  Peter Korsgaard
   115  Thomas Petazzoni
    55  Gustavo Zacarias
    37  Martin Banky
    26  Yann E. MORIN
    15  Lionel Landwerlin
    13  Mike Frysinger
    10  Paulius Zaleckas
     8  Maxime Petazzoni
     4  Konrad Eisele
     3  Chih-Min Chao
     2  Yegor Yefremov
     1  Andy Gibbs
     1  Felipe Contreras
     1  Frederik Pasch
     1  Heiko Zuerker
     1  Javier Viguera
     1  Luca Ceresoli
     1  Marcelo Roberto Jimenez
     1  Marcus Osdoba
     1  Matt Johnson
     1  Paul Burton
     1  Paul Jones
     1  Stanislav Bogatyrev
     1  Thomas Rudin
     1  Will Newton

The things I worked on are: cleanup of the kconfig patches and switch to the 2.6.36 one, removal of old-style hooks and many other small package cleanups, Gtk+ upgrade and documentation improvements. I’m also very happy to see that the number of contributors is increasing, as is the number of questions asked on the list, on IRC and on the bug tracker.

Buildroot developer day

A Buildroot Developer Day, meeting of some of the Buildroot developers, took place on October, 29th in Cambridge, UK, just after the Embedded Linux Conference Europe. Peter Korsgaard (Buildroot maintainer), Lionel Landwerlin (contributor), Yann E. Morin (contributor, Crosstool-NG developer), Nicolas Ferre (Atmel), Patrice Vilchez (Atmel) and Thomas Petazzoni (Free Electrons) attended the meeting.

There has been discussions about cleaning up board support, libtool issues, Crosstool-NG integration, toolchain cleanup, top-level parallel make and package management. A report has been posted to the Buildroot mailing list.

The next Buildroot Developer Day will take place on Monday, 7th February, just after FOSDEM, in Brussels.

Roadmap for 2011.02

Here are some of the things that are in the pipeline, for 2011.02 if everything goes well.

  • Conversion of more (all remaining?) packages to the gentargets and autotargets infrastructures.
  • Cleanup of board support in Buildroot. We will now use minimal defconfigs for both Buildroot itself and for kernel configuration. The messy target/device/ directory will be cleaned-up. And we will add support for some emulated boards based on Qemu (x86, ARM, MIPS, PowerPC, SH4). This work is already done, so it’s very likely to be in 2011.02
  • Better support of devtmpfs, mdev and udev. An option will allow the user to select between static device creation and those three techniques for having a dynamic /dev. This is also ready.
  • Improvements in the external toolchain configuration and setup. Buildroot will be able to automatically download some well-known external toolchains, making them easier to use.
  • The Buildroot internal toolchain build process will be reworked, with conversion of most of the code to the package infrastructures, and the toolchain binaries and sysroot move to $(HOST_DIR). This will make it much, much easier to use the toolchain produced by Buildroot outside of Buildroot, and will allow us to generate a SDK to be shared with application developers, without requiring them to run Buildroot. See the report from the Buildroot Developers Day for details. This work has already been started by Gustavo Zacarias, and at least part of it will be in 2011.02.
  • Package management will be improved. Buildroot will know which package installed what in the different directories, and will therefore be able to cleanly remove a package from the system if it has been disabled in the configuration, without requiring a completely clean rebuild. Later on, this work could be used to generate .ipk packages, but for the moment, the focus is on being able to remove libraries and applications from the system when they are unselected from the configuration. This work has already been started by Lionel Landwerlin, and we will do our best to merge it into 2011.02.
  • Support for non-MMU architectures, and particularly Blackfin. Mike Frysinger has already posted patches to add Blackfin and support non-MMU for several packages. This is really a good news, as Buildroot is a good fit for non-MMU systems.
  • Public access to regression tests results

Toolchain cleanup work and board cleanup work are really interesting pieces, because they are the two remaining parts of Buildroot that haven’t been cleaned up and/or rewritten since the Buildroot project came back to life late 2008/early 2009. There are of course still some areas that need improvements of course, but for me, those two pieces are really closing the large cleanup work that has been started almost two years ago.

Of course, don’t hesitate to contact the Buildroot mailing-list, the IRC channel or the bug tracker if you have any questions or issues in using Buildroot.

Buildroot 2010.08 released!

Buildroot logoOn the last day of August, just in time, the 2010.08 version of Buildroot has been released. For the record, Buildroot is an easy-to-use embedded Linux build system: it can build your toolchain, your root filesystem with all its components (Busybox, libraries, applications, etc.), your kernel and your bootloaders, or any combination of these components.

Amongst the interesting changes in this version :

  • Complete rewrite of the bootloader build code. It contained a lot of legacy, unused and unclear stuff, it is now much easier to use and extend. We’ve removed support for Yaboot and added support for the new Barebox bootloader, and all the code to support AT91Bootstrap, AT91DataFlashBoot, U-Boot, Grub and Grub 2 has been rewritten.
  • Complete rewrite of the Linux kernel build code. It was also complicated to use, with an horribly complicated kernel version selection mechanism, the new code is much easier to configure and use.
  • The configuration file .config is now located in the out-of-tree directory when the O= option is used. So typically, for an out-of-tree build (which are very convenient when using the same Buildroot source tree for different projects/tests), you could do : mkdir ~/myoutput ; make O=~/myoutput menuconfig ; make O=~/myoutput
  • Support for building NPTL toolchains with uClibc, using the latest uClibc snapshots.
  • Support for the gconfig Gtk-based configurator, in addition to the already available menuconfig and xconfig
  • A particular effort has been put on fixing many of the bugs in our Bugzilla, improving robustness thanks to automated random builds, and converting even more packages to the generic and autotools infrastructure
  • Various things have also been deprecated: support for the CRIS, IA64, Sparc64 and Alpha architectures, support for Gtk over DirectFB (which is at the moment not supported upstream), Java support (no maintainer has volunteered to maintain this in Buildroot)
  • Many components have been bumped to newer versions
  • The shared configuration cache, which allowed to speed up the configuration of different packages, has been disabled by default, since it was causing a lot of problems with certain package configurations

I’ve again contributed to a significant portion of this release, being the author of the bootloader build code cleanup, the Linux kernel build code rewrite, leading an effort to reduce the number of outstanding bugs in our Bugzilla and many other little things. The contributors for this release are shown below :

   175  Peter Korsgaard
   168  Thomas Petazzoni
    38  Gustavo Zacarias
    18  cmchao
     8  Luca Ceresoli
     7  Paul Jones
     6  Lionel Landwerlin
     6  Malte Starostik
     5  Yann E. MORIN
     3  Julien Boibessot
     3  Khem Raj
     2  Dmytro Milinevskyy
     2  Francois Perrad
     2  Nick Leverton
     2  Peter Huewe
     2  Stanislav Bogatyrev
     1  Baruch Siach
     1  Bjørn Forsman
     1  Daniel Hobi
     1  Darcy Watkins
     1  Darius Augulis
     1  H Hartley Sweeten
     1  Karl Krach
     1  Kelvin Cheung
     1  Ossy
     1  Sagaert Johan
     1  Simon Pasch
     1  Slava Zanko
     1  Thiago A. Correa
     1  Will Wagner
     1  Yegor Yefremov

For the next release, there are already a few things in the pipeline :

  • Cleanup of all the board support code in Buildroot, in order to cleanly add support for more boards like BeagleBoard, Qemu boards, Calao boards, etc. We’ll use the new minimal defconfig mechanism used by the kernel. I’ve already started working on this
  • Cleanup of the package download process, to support Git and SVN download. The code has already been written by Maxime Petazzoni, reviewed on the list, so I expect it to be included fairly soon
  • Rewrite of libtool handling code, to remove some of our ugly libtool hacks. The code is currently being worked on by Lionel Landwerlin
  • Support for compiling toolchain using Crosstool-NG as a backend. The code is currently being finalized by Yann E. Morin, the author of Crosstool-NG
  • Further work on package uninstallation, clean partial rebuild. Some work has been started by Lionel Landwerlin, but it needs some discussion
  • Continue the conversion of packages to the generic and autotools infrastructures
  • I have also a ton of other things on my TODO-list : rework gdb/gdbserver support with external toolchains, rework the configuration of IPv6/RPC/locale/etc. with external toolchains, set up a Wiki-based Buildroot website with tutorials and better documentation, clean up the toolchain build process, reduce the number of “enhancement” bugs waiting in our Bugzilla, etc.

As Peter Korsgaard, Buildroot maintainer, said in the 2010.08 announcement: The next release is going to be 2010.11. Expect the first release candidate in late October and the final release at the end of November..

It is worth noting that we will be having a Buildroot Developer Day, on Friday 29th October, right after Embedded Linux Conference Europe. At least Peter Korsgaard, Lionel Landwerlin, Yann E. Morin and myself should be there.

Crosstool-NG 1.5.0 released, with new features!

Crosstool-NG, the successor of Crosstool, is a tool that automates the complicated process of building a cross-compilation toolchain. It provides a nice menuconfig interface to fine tune the configuration of the toolchain, before creating the toolchain automatically by retrieving, extracting, patching, configuring, compiling and installing the different components in the right order, with the right arguments and configuration.

Yann E. Morin, the maintainer of Crosstool-NG has just announced the release of Crosstool-NG 1.5.0, with the following new features:

  • Support for gcc 4.4
  • Experimental support for canadian-cross toolchains. Canadian-cross toolchains are toolchains that are built on machine A, to run on machine B and generate code for machine C, while usual cross-compilation toolchain are built on machine A, to run on machine A and generate code for machine B
  • Experimental support for AVR32, with support for operation as MMU-less, thanks to the newlib C library

In addition to these important features, bugs have been fixed and improvements have been made. Yann also switched the development of Crosstool-NG from Subversion to Mercurial, in order to ease community participation in the improvement of Crosstool-NG.

By the way, if you are interested in Crosstool-NG, don’t miss Yann E. Morin’s talk at the Embedded Linux Conference Europe 2009. See the program for details.

Buildroot gains better support for external toolchains

Buildroot logoBuildroot is a tool that I’ve already covered in a previous blog post. To me, its main purpose is to build the root filesystem for an embedded Linux system, with all the necessary applications and libraries. It automates the tedious process of cross-compiling and integrating all the free software components in an embedded system.

In addition to root filesystem generation, Buildroot is also known for its ability to generate a uClibc-based cross-compilation toolchain. Buildroot used to be for quite some time the only way to generate a toolchain based on this size-effective C library, but it is no longer the case with Crosstool-NG supporting glibc, uClibc and eglibc.

However, I’ve personaly never been really satisfied with uClibc generation of cross-compiling toolchains:

  • It mixes the process of the cross-compilingn toolchain generation with the process of root filesystem generation, which are, in my opinion, two very different processes. Once your toolchain is generated, you generally don’t touch it, but regenerate your root filesystem dozens or hundred of times until all your components are here and properly integrated.
  • The attention paid to toolchain generation in the Buildroot project itself is relatively small, while other projects like Crosstool-NG or vendors like Codesourcery, are specifically dedicated to providing toolchains. The fact that, for example, uClibc is the only C library supported is one example of this.
  • It might necessary, for various reasons, make sense to use an already existing toolchain.

Support for the usage of external toolchains has already been present in Buildroot for a long time, but wasn’t developed enough to be easily usable. Months ago, I’ve started to improve the situation (here, here, here and here), and last week, two other patches have been integrated.

  • The first patch, visible here removes the ugly configuration option that allows to configure the set of libraries that must be copied to the target filesystem, and replaces it with a nice selection of the C libary type: uClibc or glibc. It makes it clear that generating Linux system with the glibc library is possible with Buildroot, even if Buildroot has often been advertised as a uClibc only tool.
  • The second patch, visible here adds checks for the conformity of Buildroot configuration versus the C library configuration. There are configuration options in Buildroot that must tell whether the C library supports IPv6, supports RPC, supports locale, supports large file, etc. These options must be set in the configuration interface according to the C library configuration, because some userspace packages depend on them. The added checks verify that the value set to these options match the configuration of your C library

So, now, external toolchains are a little bit easier to use with Buildroot, and your own vendor toolchain, Codesourcery toolchains or any other toolchain can be used with Buildroot. The only requirement is that the toolchain supports the sysroot feature, which is very common in most toolchains.