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 2010.08 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.

Linux 2.6.33 features for embedded systems

Interesting features for embedded Linux system developers

Penguin workerLinux 2.6.33 was out on Feb. 24, 2010, and to incite you to try this new kernel in your embedded Linux products, here are features you could be interested in.

The first news is the availability of the LZO algorithm for kernel and initramfs compression. Linux 2.6.30 already introduced LZMA and BZIP2 compression options, which could significantly reduce the size of the kernel and initramfs images, but at the cost of much increased decompression time. LZO compression is a nice alternative. Though its compression rate is not as good as that of ZLIB (10 to 15% larger files), decompression time is much faster than with other algorithms. See our benchmarks. We reduced boot time by 200 ms on our at91 arm system, and the savings could even increase with bigger kernels.

This feature was implemented by my colleague Albin Tonnerre. It is currently available on x86 and arm (commit, commit, commit, commit), and according to Russell King, the arm maintainer, it should become the default compression option on this platform. This compressor can also be used on mips, thanks to Wu Zhangjin (commit).

For systems lacking RAM resources, a new useful feature is Compcache, which allows to swap application memory to a compressed cache in RAM. In practise, this technique increases the amount of RAM that applications can use. This could allow your embedded system or your netbook to run applications or environments it couldn’t execute before. This technique can also be a worthy alternative to on-disk swap in servers or desktops which do need a swap partition, as access performance is much improved. See this article for details.

This new kernel also carries lots of improvements on embedded platforms, especially on the popular TI OMAP platform. In particular, we noticed early support to the IGEPv2 board, a very attractive platform based on the TI OMAP 3530 processor, much better than the Beagle Board for a very similar price. We have started to use it in customer projects, and we hope to contribute to its full support in the mainline kernel.

Another interesting feature of Linux 2.6.33 is the improvements in the capabilities of the perf tool. In particular, perf probe allows to insert Kprobes probes through the command line. Instead of SystemTap, which relied on kernel modules, perf probe now relies on a sysfs interface to pass probes to the kernel. This means that you no longer need a compiler and kernel headers to produce your probes. This made it difficult to port SystemTap to embedded platforms. The arm architecture doesn’t have performance counters in the mainline kernel yet (other architectures do), but patches are available. This carries the promise to be able to use probe tools like SystemTap at last on embedded architectures, all the more if SystemTap gets ported to this new infrastructure.

Other noticeable improvements in this release are the ability to mount ext3 and ext2 filesystems with just an ext4 driver, a lightweight RCU implementation, as well as the ability to change the default blinking cursor that is shown at boot time.

Unfortunately, each kernel release doesn’t only carry good news. Android patches got dropped from this release, because of a lack of interest from Google to maintain them. These are sad news and a threat for Android users who may end up without the ability to use newer kernel features and releases. Let’s hope that Google will once more realize the value of converging with the mainline Linux community. I hope that key contributors that this company employs (Andrew Morton in particular) will help to solve this issue.

As usual, this was just a selection. You will probably find many other interesting features on the Linux Changes page for Linux 2.6.33.

CALAO boards supported in mainline U-Boot

CALAO SystemsI’m happy to announce that a couple days ago, support for the CALAO SBC35-A9G20, TNY-A9260 and TNY-A9G20 boards made its way into the U-Boot git repository. Sadly, it’s not possible to boot from an MMC/SD card with the SBC35 yet, but it’s something I’m currently working on.

Support for all these cards will be available in the next U-Boot release, due in November.

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 Free Electrons’ participation 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 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!

Linux 2.6.30 – New features for embedded systems

Interesting features in Linux 2.6.30 for embedded system developers

Linux 2.6.30 has been released almost 1 month ago and it’s high time to write a little about it. Like every new kernel release, it contains interesting features for embedded system developers.

The first feature that stands out is support for fastboot. Today, most devices are initialized in a sequential way. As scanning and probing the hardware often requires waiting for the devices to be ready, a significant amount of cpu time is wasted in delay loops. The fastboot infrastructure allows to run device initialization routines in parallel, keeping the cpu fully busy and thus reducing boot time in a significant way. Fasboot can be enabled by passing the fastboot parameter in the kernel command line. However, unless your embedded system uses PC hardware, don’t be surprised if you don’t get any boot time reduction yet. If you look at the code, you will see that the async_schedule function is only used by 4 drivers so far, mainly for disk drives. You can see that board support code and most drivers still need to be converted to this new infrastructure. Let’s hope this will progress in future kernel releases, bringing significant boot time savings to everyone.

Tomoyo LinuxLinux 2.6.30 also features the inclusion of Tomoyo Linux, a lightweight Mandatory Access Control system developed by NTT. According to presentations I saw quite a long time ago, Tomoyo can be used as an alternative to SELinux, and it just consumes a very reasonable amount of RAM and storage space. It should interest people making embedded devices which are always connected to the network, and need strong security.

Another nice feature is support for kernel images compressed with bzip2 and lzma, and not just with zlib as it’s been the case of ages. The bzip2 and lzma compressors allow to reduce the size of a compressed kernel in a significant way. This should appeal to everyone interested in saving a few hundreds of kilobytes of storage space. Just beware that decompressing these formats requires more CPU resources, so there may be a price to pay in terms of boot time if you have a slow cpu, like in many embedded systems. On the other hand, if you have a fast cpu and rather slow I/O, like in a PC, you may also see a reduction in boot time. In this case, you would mainly save I/O time copying a smaller kernel to RAM, and with a fast cpu, the extra decompression cost wouldn’t be too high.

However, if you take a closer look at this new feature, you will find that it is only supported on x86 and blackfin. Alain Knaff, the author of the original patches, did summit a patch for the arm architecture, but it didn’t make it this time. Upon my request, Alain posted an update to this arm patch. Unfortunately, decompressing the kernel no longer works after applying this patch. There seems to be something wrong with the decompression code… Stay tuned on the LKML to follow up this issue. Note that the blackfin maintainers took another approach, apparently. They didn’t include any decompression code on this architecture. Instead, they relied on the bootloader to take care of decompression. While this is simpler, at least from the kernel code point of view, this is not a satisfactory solution. It would be best if the arm kernel bootstrap code took care of this task, which would then work with any board and any bootloader.

Another interesting feature is the inclusion of the Microblaze architecture, a soft core cpu on Xilinx FPGAs. This MMU-less core has been supported for quite a long time by uClinux, and it’s good news that it is now supported in the mainline kernel. This guarantees that this cpu will indeed be maintained for a long time, and could thus be a good choice in your designs.

Other noteworthy features are support for threaded interrupt handlers (which shows that work to merge the real-time preempt patches is progressing), ftrace support in 32 and 64 bit powerpc, new tracers, and of course, several new embedded boards and many new device drivers.

As usual, full details can be found on the Linux Kernel Newbies website.

Linux kernel 2.6.29 – New features for embedded users

Tuz Linux logoThe 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 community.

uClibc 0.9.30 is available

About one year and a half after the release of the previous stable version, the release of uClibc 0.9.30 is a great event in the embedded Linux community. uClibc is a replacement for the glibc C library, implementing most of the features of glibc, while retaining a much smaller size and an incredible level of configurability.

The only changelog available is a list of Subversion commits that occurred between the 0.9.29 and the 0.9.30 releases, so it is quite difficult to extract what are the important bits. However, a news from August 2008 on website gives an idea of what happened in the 0.9.30 version :

  • a lot of fixes for the various architectures, and other tweaks and improvements
  • an improved configurability that allows to enable/disable a larger number of features, now including
    • Realtime-related family of SUSv functions (option UCLIBC_HAS_REALTIME, which enables aio_*() functions, mq_*() functions, mlock() family of functions, sched_*() functions, sem_*() functions, a few signal-related functions and the timer_*() functions). Threading support requires the realtime functions, so it depends on this option.
    • Advanced realtime-related family of SUSv functions (option UCLIBC_HAS_ADVANCED_REALTIME, which enables a few advanced clock_*() and mq_*() functions, and a large number of posix_spawnattr_*() and posix_spawn_*() functions)
    • epoll (option UCLIBC_HAS_EPOLL)
    • extended attributes (option UCLIBC_HAS_XATTR)
    • other options to enable/disable compatibility/deprecated APIs
  • it is now possible to build uClibc without network support at all. The global option is UCLIBC_HAS_NETWORK_SUPPORT, and can be further refined with UCLIBC_HAS_SOCKET to enable just the socket support (for example if only Unix sockets are used), UCLIBC_HAS_IPV4 to get IPv4 functionality, which of course requires the socket support, and UCLIBC_HAS_IPV6 for IPv6.

A quick look at the differences between the available options allows to see another set of features:

  • Support for the AVR32 and Xtensa architecture has been added
  • A configuration option to enable non-functional stubs for features that are not implemented on a given architecture. This option for example enables a stub fork() function on non-MMU architectures so that applications can easily be recompiled, without checking all the fork() sites from the beginning
  • Options to enable/disable Linux-specific or BSD-specific functions

The allnoconfig setup with shared library is reported to have been reduced by 30%, though the allnoconfig setup doesn’t necessarily correspond to a classical usage of uClibc.

The tarball is available here.

Crosstool-ng 1.3.0 released!

Crosstool-ng is a tool that allows automated building of cross-compiling toolchain, easing a process known to be very difficult. Crosstool-ng has been started as a rewrite of Crosstool, the famous tool authored by Dan Kegel. Now Crosstool-ng offers several improvements over Crosstool: an active development community, stable releases, support of uClibc, glibc and eglibc, a menuconfig configuration interface, a good documentation, etc.

Yann Morin, the lead developer of Crosstool-ng announced today the release of Crosstool-ng 1.3.0. He says: « There has been many improvements, new features and bug fixes all around. If I had to, my pick would be the support for the gcc 4.3 series. But I would also have to tell you about the latest uClibc version, support for eglibc, and the ability to build bare-metal compilers, and the list would not yet be complete… »

He also mention that SuperH and IA-64 can now build a minimalist C-only toolchain, so the support for these architectures is not complete yet, but progressing. Of course, most components have been updated: new versions, new features, updated patchsets, etc. It for example include support for the latest version of uClibc, 0.9.30, released only two weeks ago.

The Changelog is available, as is a tarball of the new release.

If you need to build some cross-compiling toolchain, you definitely should take a look at Crosstool-ng. It’s great, and well supported: Yann is both very responsive and very helpful when problems are being reported.