Thomas Petazzoni – Page 35

Buildroot 2010.02 released, contributions from Bootlin!

Buildroot logo Buildroot is a embedded Linux system build system. It automates the process of downloading, configuring, compiling and installating all the components of an embedded Linux system, from Busybox to more complicated software stacks using Gtk, Qt, X.org, Gstreamer, etc. Buildroot is easy to use and extend, making it a nice choice for small to medium-sized embedded Linux systems.

As promised by the fixed-release schedule, a 2010.02 release has been published on Friday, with numerous improvements over the previous version 2009.11, many of which are part of the general cleanup process that the project is doing since the beginning of 2009. These improvements are detailed in the project CHANGES file.

Thomas Petazzoni, from Bootlin, implemented several of these improvements :

Creation of a package infrastructure for non-autotools packages. Buildroot had for a long time an infrastructure to factorize the code needed to build packages based on the autotools build systems. But all other packages were using hand-made Makefiles, which were hard to write and generated a lot of code duplication. Therefore, we have introduced an infrastructure that makes adding new packages much easier, and which allows us to cleanup the existing codebase significantly by factorizing a lot of common code. The autotools infrastructure has also been reworked on top of the generic infrastructure to avoid code duplication as well. At the same time, we have significantly improved the documentation on how to add new packages. This infrastructure is a building block that will allow us to easily add more features to all packages in Buildroot (such as package generation).
Removal of the external toolchain source mechanism, which was merged with the normal toolchain building procedure. This special casing was implemented to allow the compilation of AVR32 toolchains, but such an additional complexity wasn’t needed. Now, Buildroot continues to build AVR32 toolchains as it used to do, but the code is much cleaner. Another illustration of our large cleanup effort.
Many, many, many fixes to different packages, many of them to ensure that we do not depend on development packages being installed on the host. This is very important to ensure that our build procedure is as independent as possible from the development machine configuration.

From the list of contributors, ordered by the number of patches, Thomas Petazzoni of Bootlin has been the first Buildroot contributor for this last release :

$ git shortlog -e -n -s 2009.11..2010.02  (removed e-mail addresses)
139 Thomas Petazzoni
124 Peter Korsgaard
26  Lionel Landwerlin
23  Gustavo Zacarias
7   Julien Boibessot
4   Nigel Kukard
4   Sven Neumann
2   Anders Darander
2   Chris Packham
2   Daniel Mack
2   H Hartley Sweeten
2   Richard van Paasen
2   Will Wagner
2   William Wagner
2   Yann E. MORIN
1   Cameron Hutchison
1   Clark Rawlins
1   Francisco Gonzalez
1   Francisco Gonzalez Morell
1   Hans-Christian Egtvedt
1   Lionel Landwerlin
1   Ormund Williams
1   Rob Alley
1   Sagaert Johan
1   grante

For the next release, we will work on additional cleanup of Buildroot and particularly the target/ directory, which contains the code to build the Linux kernel, different bootloaders, and to generate the final root filesystem image in various formats. Improving support for external toolchains is also on our TODO list : supporting multilib toolchains such as the CodeSoucery toolchain, and fixing a long-standing issue with libtool.

Don’t hesitate to try Buildroot, and to report your successes and failures on the mailing-list, in our bug tracker, or on our IRC channel, #uclibc on Freenode.

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 simplified for users!

Buildroot logo Yesterday, a set of patches I’ve authored that aims at simplifying Buildroot for users has been merged into the official version of the project, and will therefore be part of the next stable release (scheduled for November, according to our 3 months release cycle). This work is probably my major contribution to Buildroot, outside of external toolchain support and various fixes here and there. Here are quick details about the improvements brought by these patches :

Remove the “project” feature. The project feature removal was the main point of this patch set. This feature, that allows to compile a system for different, but very similar platforms, without recompiling everything from scratch, was rarely used and introduced a lot of complexity in the usage of Buildroot for newcomers. Who hasn’t been confused by this project_build_arm directory? This thing is gone now.
Remove the BOARD/LOCAL feature, which duplicates another way of adding support for new targets in Buildroot. This is the kind of feature that has been added at the time Buildroot was basically unmaintained, when nobody was able to say « Hey, but you’re just trying to-reimplement something that already exists »
Move all output directories in an output directory. By default, when Buildroot is compiled, it generates several directories in the middle of its source code. Now, with this patch, everything is grouped into an output directory, unless out-of-tree compilation is used, of course (with O=)
Remove TOPDIR_PREFIX and TOPDIR_SUFFIX since the same effect could already be done using out-of-tree compilation with O=. Another duplicated feature that should never have reached the tree.
Rename the output directories. Now that everything is properly stored in an output directory, it was time to rename the subdirectories to make them more meaningful. So now, we have build where all packages are built, images that contains the final binary images of the root filesystem and the kernel, staging which contains the staging directory (all packages installed with their development headers and libraries), target that contains the root filesystem for the target (without the device files), host that contains the installation of the host tools that Buildroot requires for its execution, stamps that contains the stamp files used by Buildroot to keep track of the compilation progress. Therefore, all directories such as build_ARCH or toolchain_build_ARCH have disappeared.
Major documentation update, to of course make sure that our documentation is up-to-date with the latest changes.

Getting all these changes mainlined is really a nice thing. I also have tons of other ideas to improve Buildroot infrastructure, and I’m sure the coming Buildroot Developer Day will be a great opportunity to discuss these.

First Buildroot Developer Day after ELCE, on October 17th in Grenoble, France

Buildroot logo The first Buildroot Developer Day will take place on Saturday, October 17th in Grenoble, France, just the day after Embedded Linux Conference Europe. This Developer Day aims at allowing Buildroot developers to meet and exchange ideas on the project and its future.

As the number of places is limited, interested candidates are invited to send an e-mail to Peter Korsgaard (jacmet at uclibc dot org) and Thomas Petazzoni (thomas dot petazzoni at free-electrons dot com).

Peter Korsgaard and I are organizing this Developer Day thanks to the sponsorship of Calao Systems (offering the location for the meeting) and Bootlin (offering free lunch to the participants).

Embedded Linux Conference Europe 2009 program

As we announced a few months ago, Embedded Linux Conference 2009 will take place in Grenoble, France on October 15th and 16th. The list of sessions has just been published online, and as usual, it is a very exciting list of in-depth technical talks.

Because of my involvement in Buildroot, I’m particularly interested in the numerous talks about embedded Linux build systems: Florian Fainelli will talk about OpenWRT (which is not only dedicated to Wifi routers, but is a generic embedded Linux build system, built as a fork of Buildroot), Gordon Hecker on e2factory (a build system I’ve never heard of until now, but conferences are great to discover new tools and projects), Cedric Hombourger on OpenEmbedded (I will be particularly happy to meet Cedric again since I had the chance to work with him six years ago), Marcin Jusziewicz on OpenEmbedded again, Robert Schwebel on PTXdist and finally Alex de Vries on what seems to be a more generic talk about build systems.

Of course, besides build systems, a lot of other topics will be covered. I’ve noted things such as the talk on Canola by Gustavo Barbieri, the boot time presentation by Grégory Clément, the device tree talks by Wolfram Sang and Vitaly Wool, the talk by Alessandro Rubini in order to meet one of the author of Linux Device Drivers, the power management and clock management talks also.

Bootlin will obviously be present during this conference :

Michael Opdenacker, my colleague, will give a talk entitled Update on boot time reduction techniques
Michael, again, will be the chair of a Small Business BOF, which should allow small companies offering services around embedded Linux to meet and exchange their ideas and experience
Finally, I will be the co-chair with Peter Korsgaard of a BOF on Buildroot
We will share a booth with our partner Calao Systems during the Minalogic Embedded Systems Exhibition. This will be another opportunity to meet.

I hope to see you in October at ELCE !

On the road to Buildroot 2009.08

Buildroot logo As I posted back in March, the Buildroot project has begun a new life since January. One of the aspects this new life is the fact that stable releases are delivered every three months. So we had one in February (2009.02), one in May (2009.05) and therefore we’re going to have one release soon in August (2009.08).

Peter Korsgaard, Buildroot’s maintainer, has just released 2009.08-rc1, a good opportunity to look at what’s new in Buildroot since the last release. To highlight Bootlin’sparticipation in the free software community, it is worth noting that in number of patches, I’m the second most important contributor to Buildroot, right after Peter, the maintainer. It’s really nice that I’ve been able to find enough time to contribute at such a level to Buildroot, and hope to be able to dedicate more time in the future to Buildroot, since we have lots of ideas to improve the project.

Back to the 2009.08 release specifically, in the notable features or improvements, we have :

Improvement of external toolchain support. I’ve already posted about this specific feature, that I find very important. Several reports from people using this feature have been received since then, which means that it is a useful feature for some of the Buildroot users. So, we have now support for glibc toolchains, the configuration provided to Buildroot is verified against the real toolchain configuration, the copy of the toolchain libraries to the target has been improved (including the C++ standard library) and other minor improvements have been. I’ve been the major contributor of these improvements, together with the reports provided by Buildroot users
Integration of the QT-based configurator. Buildroot uses the kconfig system from the kernel to allow its users to configure the different elements of the system to be built. Until now, only the ncurses interface (make menuconfig) was supported. In the 2009.08, the QT interface (make xconfig) will also be supported, adding a little more userfriendliness to Buildroot. This feature was contributed by Alper Yildirim, and I helped in polishing the remaining issues.
Support for the Xtensa architecture has been contribued by Maxim Grigoriev, from Tensilica, the company designing the Xtensa architecture.
Cleanup of X.org support. the configuration options were clarified, and mandatory dependencies on useless libraries such as libXt or libXaw were removed, some components were upgraded to fix build issues. It’s also a task I contributed to.
Of course, toolchain components have been upgraded (GCC 4.4.1, 2.6.30 kernel headers), new packages have been added (bmon, ctorrent, dosfstools, enchant, gst-plugins-bad, iw, libmms, libnl, netstat-nat, ntfsprogs, sdl_gfx, spawn-fcgi), and many more packages have been upgraded (bind, busybox, coreutils, sqlite, directfb, expat, gamin, gnuconfig, haserl, ipsec-tools, classpath, libcurl, libglib2, liblockfile, libpng, libsoup, libxml2, lighttpd, ltp-testsuite, lvm2, matchbox, memstat, gst-plugins-good, gstreamer, libogg, libvorbis, mplayer, neon, openssl, pciutils, php, qt, ruby, sawman, webkit, wpa-supplicant, xdriver_xf86-input-synaptics, xdriver_xf86-video-intel, xlib_libXfont, xlib_libXft, xlib_libXt, xproto_xproto, xserver-xorg, xutil_makedepend, xutil_util-macros)
We’re also paying a lot more attention to the bugs reported in our bugtracker than we used to do in the past. Since 2009.05, 43 reported issues have been fixed, and I except that we will fix some more before the 2009.08 release

Shortly after the 2009.08, we will set the goals for the next 2009.11 release, and I’d like to do a lot of cleanup to make Buildroot easier to use and to understand. We’ll see how things go.

In the mean time, if you’re interested in testing and improving Buildroot, don’t hesitate to grab 2009.08-rc1, try it in your conditions with your package set, and report your issues!

Switching between toolchains made easy!

It is quite common to have several toolchains and to switch back and forth between them while doing development. At least, this is something I do a lot when doing Buildroot development and debugging. As I hate typing full paths all the time, I usually put the toolchain bin/ directory into my $PATH variable, so that I can easily access the toolchain binaries. However, it means that everytime you run a new shell or everytime you want to switch from one toolchain to another, you need to modify the PATH variable manually by re-exporting it. Of course, one could easily put all the bin/ directories of all toolchains in the PATH, but that would clutter what is shown when I do arm-TAB-TAB, and that’s not nice.

So, I ended up hacking a few lines of Bash that provide me with two new commands: xtoolsadd, to add a toolchain to my PATH and xtoolsdel, to remove a toolchain from my PATH. These commands work by making the assumption that all toolchains are stored in a common directory. In my case /usr/local/xtools/ contains all the toolchains, one per subdirectory. So I have /usr/local/xtools/arm-unknown-linux-gnu for an ARM glibc-based non-EABI toolchain, or /usr/local/xtools/arm-unknown-linux-uclibcgnueabi for an ARM uClibc-based EABI toolchain).

So, now I can do things such as

xtoolsadd arm-unknown-linux-gnu

xtoolsdel arm-unknown-linux-uclibcgnueabi

Because these commands must modify the PATH variable of the current shell, they cannot be implemented as separate shell scripts, so they are in fact implemented as functions in my ~/.bashrc script. And in addition to these functions, I also implemented completion, so when you do xtoolsadd TAB-TAB, it gives you a choice of toolchains, and if you start typing one and press TAB, it will just automatically complete for you. The same thing works with xtoolsdel, of course.

To make this work, here is what you need to put in your ~/.bashrc file:

export XTOOLSDIR=/usr/local/xtools

xtoolsadd() {
    TOOLCHAINDIR=$XTOOLSDIR/$1/bin
    if [ ! -d $TOOLCHAINDIR ] ; then
        echo "Directory $XTOOLSDIR doesn't exist"
    else
        case "$PATH" in
            *"$XTOOLSDIR"*)
                ;;
            *)
                export PATH=$TOOLCHAINDIR:$PATH
        esac
    fi
}

xtoolsdel() {
    TOOLCHAINDIR=$XTOOLSDIR/$1/bin
    NEWPATH=
    found=0
    for i in $(echo $PATH | tr ":" "\n") ; do
        if [ $i == $TOOLCHAINDIR ] ; then
            found=1
        else
            NEWPATH=$NEWPATH:$i
        fi
    done
    if [ $found == 0 ] ; then
        echo "$1 is not in your PATH"
    else
        export PATH=$NEWPATH
    fi
}

_xtoolsadd() {
    cur=${COMP_WORDS[COMP_CWORD]}
    LIST=$(ls -1 $XTOOLSDIR | tr "\n" " ")
    COMPREPLY=( $( compgen -W "$LIST" -- $cur))
}

_xtoolsdel() {
    cur=${COMP_WORDS[COMP_CWORD]}
    LIST=$(echo $PATH | tr ":" "\n" | grep "^$XTOOLSDIR" | sed "s%$XTOOLSDIR/\([^/]*\)/bin%\1%")
    COMPREPLY=( $( compgen -W "$LIST" -- $cur))
}

complete -F _xtoolsadd xtoolsadd
complete -F _xtoolsdel xtoolsdel

The shell code may not be perfect or fully optimized, but it works. Of course, if you have suggestions or questions, don’t hesitate to post comments!

Buildroot gains better support for external toolchains

Buildroot logo Buildroot 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.

Linux kernel 2.6.29 – New features for embedded users

Tuz Linux logo The 2.6.29 version of the Linux kernel has just been released by Linus Torvalds. Like all kernel releases, this new version offers a number of interesting new features.

For embedded users, the most important new feature is certainly the inclusion of Squashfs, a read-only compressed filesystem. This filesystem is very well-suited to store the immutable parts of an embedded system (applications, libraries, static data, etc.), and replaces the old cramfs filesystem which had some strong limitations (file size, filesystem size and limited compression).

Squashfs is a block filesystem, but since it is read-only, you can also use it on flash partitions, through the mtdblock driver. It’s fine as you just write the filesystem image once. Don’t hesitate to try it to get the best performance out of your flash partitions. Ideally, you should even use it on top of UBI, which would transparently allow the read-only parts of your filesystem to participate to wear-leveling. See sections about filesystems in our embedded Linux training materials for details.

This new release also adds Fastboot support, at least for scsi probes and libata port scan. This is a step forward to reducing boot time, which is often critical in embedded systems.

2.6.29 also allows stripping of generated symbols under CONFIG_KALLSYMS_ALL, saving up to 200 KB for kernels built with this feature. This is nice for embedded systems with very little RAM, which still need this feature during development.

Another new feature of this kernel is the support for the Samsung S3C64XX CPUs. Of course, a lot of new boards and devices are supported, such as the framebuffer of the i.MX 31 CPU, or the SMSC LAN911x and LAN912x Ethernet controllers.

The other major features of this new kernel, not necessarily interesting for embedded systems are the inclusion of the btrfs filesystem, the inclusion of the kernel modesetting code, support for WiMAX, scalability improvements (support of 4096 CPUs!), filesystem freezing capability, filesystem improvements and many new drivers.

For more details on the 2.6.29 improvements, the best resource is certainly the human-readable changelog written by the KernelNewbies.org community.

The Buildroot project begins a new life

The Buildroot project has been around for a quite a while. For those just discovering Buildroot, it is a set of Makefiles that ease and automate the process of building a cross-compilation toolchain (based on the uClibc C library, since Buildroot has been initiated by uClibc developers) and a full embedded Linux system. Buildroot can compile over 600 packages : graphical libraries (Qt Embedded, Gtk, X.org, DirectFB), network servers (the Dropbear SSH server, several HTTP servers), and more), core components such as Busybox, DBUS, Avahi and many other free software packages that make sense on embedded systems. Of course, more packages can easily be added. Buildroot is very similar to PTXdist.

I remember using to this project and contributing to it back in 2004 when I still was an intern during my studies. One of my contributions was the writing of documentation for the project, which is still the official documentation. Since 2004, the project has evolved, but there was no clear maintainer and no stable releases. The developer community around Buildroot was not completely satisfied since no one was merging the proposed fixes and improvements, since there was no official maintainer. And Buildroot was difficult to use for users because it didn’t offer any kind of stable releas : users had to pick a random SVN checkout and cross fingers to get a reasonably-working version.

In January 2009, as part of the traditionnal new year’s resolution, Peter Korsgaard, one of the most active Buildroot developers, volunteered to step up as the official maintainer and to deliver releases. And indeed, he integrated many patches that were floating around, released several release candidates before releasing Buildroot 2009.02 on February, 12th. Since then he continues to make very interesting improvements to Buildroot, replies on the mailing list, review and merge the proposed patches. A new bug tracker has been set up, and the source code will soon be moved over the Git distributed version control system.

Definitely, it’s a new life starting for the Buildroot project. As a long-time user and occasional contributor of the project, I’m glad to see such evolution.