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

Buildroot logoThe 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).

See also the announcement of the mailing list and on Buildroot website.

Embedded Linux Conference Europe 2009 program

GrenobleAs 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 logoAs 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

or

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 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.