Tag: linux

Bootlin at Embedded World 2014, Nuremberg, Germany

Embedded World 2014, Germany

Embedded World is the world’s largest trade show about embedded systems. In 2013, it attracted around 900 exhibitors, over 22,000 visitors and almost 1,500 congress participants.

This year, Bootlin will be represented by our CEO Michael Opdenacker. This should be a great opportunity for us to understand our customers better, by meeting embedded system makers, by seeing what their needs are and what technologies they use. It will also be an opportunity to meet well known members of the technical community. In particular, here are a few well know people who are going to speak at the congress:

Don’t hesitate to contact us if you are attending this event too and are interested in knowing Bootlin better, for business, partnership or even career opportunities!

Bootlin contributions to Linux 3.13

Version 3.13 of the Linux kernel was released by Linus Torvalds on January, 19th 2014. The kernelnewbies.org site has an excellent page that covers the most important improvements and feature additions that this new kernel release brings.

As usual Bootlin contributed to this kernel: with 121 patches merged in 3.13 on a total of 12127 patches contributed, Bootlin is ranked 17th in the list of companies contributing to the Linux kernel. We also appeared on Jonathan Corbet kernel contribution statistics at LWN.net, as a company having contributed 1% of the kernel changes, right between Renesas Electronics and Huawei Technologies.

Amongst the contributions we made for 3.13:

  • Standby support added to the Marvell Kirkwood processors, done by Ezequiel Garcia.
  • Various fixes and improvements to the PXA3xx NAND driver, as well as to the Marvell Armada 370/XP clocks, in preparation to the introduction of NAND support for Armada 370/XP, which will arrive in 3.14. Work done by Ezequiel Garcia.
  • Added support for the Performance Monitoring Unit in the AM33xx Device Tree files, which allows to use perf and oprofile on platforms such as the BeagleBone. Work done by Alexandre Belloni.
  • Support added for the I2C controllers on certain Allwinner SOCs, as well as several other cleanups and minor improvements for these SoCs. Work done by Maxime Ripard.
  • Continued the work to get rid of IRQF_DISABLED, as well as other janitorial tasks such as removing unused Kconfig symbols. Work done by Michael Opdenacker.
  • Added support for MSI (Message Signaled Interrupts) for the Armada 370 and XP SoCs. Work done by Thomas Petazzoni.
  • Added support for the Marvell Matrix board (an Armada XP based platform) and the OpenBlocks A7 (a Kirkwood based platform manufactured by PlatHome). Work done by Thomas Petazzoni.

In detail, the patches contributed by Bootlin are:

New training materials: boot time reduction workshop

We are happy to release new training materials that we have developed in 2013 with funding from Atmel Corporation.

The materials correspond to a 1-day embedded Linux boot time reduction workshop. In addition to boot time reduction theory, consolidating some of our experience from our embedded Linux boot time reduction projects, the workshop allows participants to practice with the most common techniques. This is done on SAMA5D3x Evaluation Kits from Atmel.

The system to optimize is a video demo from Atmel. We reduce the time to start a GStreamer based video player. During the practical labs, you will practice with techniques to:

  • Measure the various steps of the boot process
  • Analyze time spent starting system services, using bootchartd
  • Simplify your init scripts
  • Trace application startup with strace
  • Find kernel functions taking the most time during the boot process
  • Reduce kernel size and boot time
  • Replace U-Boot by the Barebox bootloader, and save a lot of time
    thanks to the activation of the data cache.

Creative commonsAs usual, our training materials are available under the terms of the Creative Commons Attribution-ShareAlike 3.0 license. This essentially means that you are free to download, distribute and even modify them, provided you mention us as the original authors and that you share these documents under the same conditions.

Special thanks to Atmel for allowing us to share these new materials under this license!

Here are the documents at last:

The first public session of this workshop will be announced in the next weeks.
Don’t hesitate to contact us if you are interested in organizing a session on your site.

Linux init failures now easier to debug

If you are an embedded Linux developer too, you have probably been frustrated by the lack of information from the Linux kernel when it failed to start the init process when you’re building a new root filesystem. The only thing you get is No init found, and this could hide many different causes:

  • No init program candidate found at all
  • Some init program candidates exist but they can’t be executed, for multiple possible causes (missing execute permissions, failed to load shared libraries, executable compiled for an unknown architecture…)

The good news is that this source of frustration will be gone in Linux 3.13. Thanks to a Bootlin commit merged on Nov. 13, 2013, whenever an attempt to execute an init program candidate fails, there is a message in the console detailing the executable path and the error code. For example:

Starting init: /sbin/init exists but couldn't execute it (error -13)

When you get such a message, all you have to do is lookup the error code in include/uapi/asm-generic/errno-base.h or maybe in uapi/asm-generic/errno.h. In the above example, the -13 code meant permission denied, typically because of missing execution rights.

This had been annoying me for a long time, and I am glad that the Linux kernel community accepted my improvement!

By the way, many more improvements to the Linux kernel from Bootlin are currently getting merged in 3.13. See all our contributions to the Linux kernel.

Linux 3.12 released, Bootlin 14th contributor by number of commits

Emperor penguins pictureThe 3.12 kernel has just been released by Linus Torvalds, who summarized what he considers to be the major improvements offered by this release: improvements to the dynamic tick code, support infrastructure for DRM render nodes, TSO sizing and the FQ scheduler in the network layer, support for user namespaces in the XFS filesystem, multithreaded RAID5 in the MD subsystem, offline data deduplication in the Btrfs filesystem.

As usual, Bootlin contributed to the Linux kernel during this cycle, and according to the statistics at KPS, Bootlin is the 14th contributor in terms of number of commits, as a company. Bootlin contributed 185 patches to this kernel release, on a total of 10920 patches. Note that this classification includes the “Unknown” company which ranks first, gathering the contributions from all the contributors that are not known to be affiliated to any company.

The highlights of our contributions are:

  • Addition of support for the HX8369 LCD controller to the driver we had contributed earlier for the HX8357 LCD controller, in drivers/video/backlight/hx8357.c. These LCD controllers are used by the Crystalfontz i.MX28 boards, and this new development was done primarily by Alexandre Belloni.
  • Addition of a driver for the Nuvoton NAU7802 ADC chip on I2C, in drivers/iio/adc/nau7802.c. Some initial work was done by Maxime Ripard, but lots of debugging and additional work was done by Alexandre Belloni, who also pushed the driver to the mainline.
  • Added Device Tree information for the PMU unit on Atmel SAMA5D3 platforms, which allows to use perf on these platforms. Done by Alexandre Belloni.
  • Addition of a Device Tree binding to the mvebu-mbus driver, which controls the configuration of the MBus on Marvell EBU platforms (Armada 370/XP, Kirkwood, Dove, etc.). This binding took a lot of discussion time, and many iterations before reaching a state that was considered acceptable for mainline, but it has finally been merged in 3.12. The core of this work was done by Ezequiel Garcia, with several contributions from Thomas Petazzoni to convert existing platforms to the new APIs.
  • Many cleanups and improvements to the nand_pxa3xx driver, which for the moment is used for the NAND controller on PXA3xx, but that we are currently extending to also cover the NAND controller of Armada 370/XP platforms. In 3.12, only some cleanups have been integrated, and we are currently submitting the more important patches for mainline integration. This work was done by Ezequiel Garcia.
  • Cleanups, and conversion to CLOCKSOURCE_OF_DECLARE of the Armada 370/XP clocksource driver. Done by Ezequiel Garcia.
  • Extension of the Marvell I2C driver to use a new feature of the I2C controller found on Armada 370/XP, which allows to program an entire transaction at once, instead of having interrupts at each step of the transaction. This work was done by Gregory Clement.
  • The quest of removing unneeded ->init_irq() callbacks in machine descriptors continued, with Maxime Ripard removing 4 additional occurrences of this in mach-shmobile.
  • Cleanups and improvements to the sun4i clocksource driver, used on Allwinner SOCs. Done by Maxime Ripard.
  • Introduction of the initial support for the Allwinner A31 SOC and its WITS Columbus evaluation kit, as well as initial support for the Allwinner A20 SOC and the Olimex A20-Olinuxino-Micro and Cubieboard2 board, both based on the Allwinner A20 SOC. This includes clock support, pinctrl support, Ethernet support where applicable, and more. Work done by Maxime Ripard.
  • Michael Opdenacker continued his fight against IRQF_DISABLED and removed more occurrences of them. Michael also fixed a few issues in some Kconfig files.
  • Fixed big-endian issues in the Marvell mvneta Ethernet driver and the Marvell XOR driver, in preparation for the addition of big-endian support to the mach-mvebu platform. Done by Thomas Petazzoni.
  • Conversion of a few more Kirkwood platforms to the Device Tree, and removal of legacy support for other Kirkwood platforms that were already converted to the Device Tree. Done by Thomas Petazzoni.
  • Addition of the support for the Armada XP based AXP-WiFi AP board, from Marvell. Done by Thomas Petazzoni.
  • Improvements of the MSI infrastructure in the kernel: consolidation of code between architectures, addition of a registry of msi_chip. This preparatory work was needed to introduce MSI support for Armada 370/XP, which should hopefully make its way into 3.13. Work done by Thomas Petazzoni.

In details, our contributions were:

Embedded Linux and kernel engineer job openings

Bootlin team

We’re getting busier than ever! Bootlin is looking for developers:

  • With experience developing embedded Linux systems
  • With experience developing device drivers for the Linux kernel, and porting Linux on new hardware. See our contributions to the mainline Linux kernel!
  • With technical writing skills and an interest for training

We need to fill at least 2 open positions in the next months, and more will follow in 2014.

Newly graduated engineers are welcome too, provided they already have experience in the above technical fields or with Free Software development.

This time, we are looking for people who will be able to join one of our offices in France (Toulouse or Avignon), to strengthen our engineering teams there.

  • Toulouse is a dynamic city with lots of high-tech and embedded systems companies in particular. Our office in Colomiers can easily be reached by train from downtown Toulouse if you wish to settle there. You would be working with Maxime Ripard and our CTO Thomas Petazzoni.
  • Our main office is settled in Orange in the heart of the Provence region, close to Avignon, a smaller but dynamic city too. It enjoys a sunny climate and the proximity of the Alps and the Mediterranean sea. Accommodation is very affordable and there are no traffic issues! You would be working with our founder Michael Opdenacker and of course remotely with the rest of the engineering team. In particular, we are interested in foreign engineers who could help us develop our services in their home countries.

If you are unable to relocate this time, don’t hesitate to contact us anyway. Depending on your profile and experience, we are still planning to open home based jobs in a few months or years from now.

If you are interested in these positions, here are nice opportunities to meet us in the next weeks:

See a full description and details about how to contact us.

Bootlin at the ARM Kernel Summit, the Embedded Linux Conference and the Buildroot Developers Meeting

Late october will be a busy moment for all the embedded Linux developers meeting in Edinburgh, UK. The Linux Foundation is organizing a number of conferences here, including the Embedded Linux Conference Europe (October 24-25) and LinuxCon Europe (October 21-23), and many co-located other events.

Bootlin will be present at several of these events:

  • First, three Bootlin engineers will be present at the ARM kernel summit on October 22nd and 23rd. The ARM kernel summit is an invitation-only conference, organized in relation with the Linux Kernel Summit. Gregory Clement, Maxime Ripard and Thomas Petazzoni, engineers at Bootlin have been invited due to their participation to the ARM support in the kernel, mainly on Allwinner SOCs for Maxime and on Marvell SOCs for Gregory and Thomas. Being present at this event is an excellent opportunity to be part of the discussion that shapes the future of ARM support in Linux, and strengthen our relations with other members of this growing community.
  • Then, the entire technical team of Bootlin will attend the Embedded Linux Conference, on October 24th and 25th. Several talks will also be given by Bootlin engineers:
    • On Thursday, 24th October at 11:40 AM, Thomas Petazzoni will give a talk titled Device Tree for dummies!, which will give an introduction to the Device Tree on ARM: what it is, how it is compiled, how it used by the kernel, how Device Tree bindings are defined, how drivers are affected by the Device Tree, etc.
    • At the same time in another room, Michael Opdenacker will lead a Bird of a Feather session dedicated to Small Businesses in the embedded Linux world. Exchanging experiences, networking with other companies working in the same field, etc.
    • Still on Thursday, at 3 PM, Gregory Clement will give a talk on the Linux kernel Common Clock Framework, which will be an updated version of the talk he gave at ELC earlier this year.
    • On Friday, 25th October at 9:30 AM, Thomas Petazzoni will be part of the keynote panel session dedicated to a discussion on Embedded Linux build systems together with Tim Bird (Sony Mobile), Ross Burton (Intel), and Karim Yaghmour (Opersys), the panel being moderated by Jeff Osier-Mixon (Intel).
  • On Saturday 26th and Sunday 27th October, the Buildroot community is organizing its traditional Developers Meeting, to which Thomas Petazzoni will participate. Some of the core Buildroot developers will join for two days of discussion and work to improve this embedded Linux build system.

As you can see, this will be a very interesting and busy week, and we’re all looking forward to meeting more embedded Linux developers and learning about the latest technologies in this field.

Bootlin the top #18 contributor to the 3.11 kernel

The 3.11 Linux kernel has now been released by Linus Torvalds, and as usual as thousands of patches coming from a large number of companies and contributors. For this release, Bootlin has contributed a total of 128 patches (yes, exactly 2^7), which makes Bootlin the 18th contributor in the list of companies contributing to the kernel, according to http://www.remword.com/kps_result/3.11_whole.html, before Broadcom and Cisco, and after ARM and Oracle. It is also the first time that six different engineers from Bootlin contribute code to the Linux kernel in a single release!

As usual, most of our contributions were centered around support for the Marvell Armada 370 and XP SOCs, the Allwinner SOCs and the Crystalfontz i.MX28 platforms:

  • Added support for the PCIe controllers of the Armada 370 and Armada XP platforms, and used it for the already supported Kirkwood platform. Supporting PCIe has been a very long process, which got started in December 2012, required long discussions with various kernel maintainers and multiple iterations of the patch series. Armada 370/XP was the first ARM platform to add Device Tree based PCIe support, and therefore this required many discussions to sort out the Device Tree bindings for PCIe controllers. This work was done by Thomas Petazzoni.
  • Enable an additional USB interface on the OpenBlocks AX3 platform, which is available as part of the mini-PCIe connector inside the device. This work was done by Thomas Petazzoni.
  • Cleaned up all the Kirkwood platform Device Tree files to assign the pin muxing configurations to the appropriate devices. This work was done by Thomas Petazzoni.
  • Made various cleanups and improvements in the Armada 370/XP platform code (in arch/arm/mach-mvebu) to make it possible to support different base address for the internal registers depending on the board being used. Many hardcoded physical addresses were removed, as well as the static virtual to physical mapping. This work was done by Thomas Petazzoni.
  • Cleaned up many ARM platforms to remove their unneeded ->init_irq() callback, and also the ->map_io() callback which we changed to default to calling debug_ll_io_init() when not provided. This work was done by Maxime Ripard.
  • Extended the ssd1307fb driver that we contributed a few releases ago to also support the SSD1306 device. The SSD1306 and SSD1307 are OLED screens controlled over I2C that are used on Crystalfontz i.MX28 platforms. We also optimized significantly the communication with the SSD130x devices. This work was done by Maxime Ripard.
  • Added an Ethernet driver for the Allwinner SOCs. The work was initially done by Stefan Roese, and our engineer Maxime Ripard did all the final cleanup, development of an MDIO driver, and integration with all the Device Tree files of the Allwinner platforms.
  • Added support for the Allwinner I2C controller, by re-using and extending the existing i2c-mv64xxx driver used on Marvell platforms, since the hardware block was very similar. The Allwinner Device Tree files were also updated to add the I2C controllers. This work was done by Maxime Ripard.
  • Added basic support for the Allwinner A10s SOC: pin muxing information and Device Tree information. This work was done by Maxime Ripard.
  • Added support for the Olimex A10s-Olinuxino-micro, a new hardware platform manufactured by Olimex that uses the Allwinner A10s SOC. This work was done by Maxime Ripard.
  • Implemented a “Device Bus” driver for the Marvell SOCs, that allows to configure the access to NOR flash and other devices connected to the memory bus. It has been used to enabled NOR support on the Armada XP DB development platform. This work was done by Ezequiel Garcia.
  • Fixed a few bugs in the IIO subsystem, and a build failure on AT91 platform when CONFIG_PHYLIB was not enabled. This work was done by Alexandre Belloni.
  • Fixed the ARM low-level code that handles compatibility with ATAG bootloaders, to properly convert 32 bits memory sizes passed by the bootloader into 64 bits cells of the Device Tree, when LPAE is used. This work was done by Gregory Clement.
  • Michael Opdenacker made a few improvements and fixes to the documentation.

For the upcoming 3.12, we already have 131 patches lined up, and a few more will probably show up after this blog post is written. Over the last release cycles, Bootlin has become a regular contributor to ARM support in the Linux kernel, and we’re looking forward to doing more contributions in the future.

The details of our 3.11 contributions is:

Bootlin contributions to the 3.10 kernel

The 3.10 Linux kernel has been released a few days ago. According to LWN, with almost 13.500 non-merge commits, the 3.10 has been the busiest ever, and also the fastest. Bootlin engineers again contributed to this release, with 99 patches integrated, making Bootlin the 28th most active company contributing, right between ST-Ericsson (103 patches) and ARM (97 patches). See http://www.remword.com/kps_result/3.10_whole.html for the complete statistics.

This time, Bootlin contributions include:

  • LPAE support for the Marvell Armada XP SoC, done by Grégory Clement.
  • Fix for errata 4742 of the PJ4B CPU core (used in Armada 370/XP), which prevented booting Armada 370 platforms after ARM optimized some TLB operations. Done by Grégory Clement.
  • Support for NOR flash on Marvell Armada 370 and Armada XP SoC, done by Ezequiel Garcia
  • Addition of a mvebu-mbus driver to handle the address decoding mechanism and configurable memory windows of Marvell SoC. The mach-kirkwood, mach-orion5x, mach-dove, mach-mv78xx0 and mach-mvebu Marvell platforms are all converted to use it. Developping this driver was a requirement to enable PCIe in a Device Tree compatible way on these platforms. Done by Thomas Petazzoni.
  • Addition of Device Tree information for the PCIe controllers of the Armada 370 and Armada XP, but unfortunately not the PCIe driver itself (which will arrive in 3.11). Done by Thomas Petazzoni.
  • Support for the thermal sensor on Marvell Armada 370 and Armada XP SoC, done by Ezequiel Garcia
  • A lot of reorganization of the Device Tree compatible strings for the Allwinner ARM SoC support, to prepare for the addition of additional SoCs in the future. Done by Maxime Ripard.
  • Improvements to the Allwinner pinctrl driver, with support for the A10 and A13 SoC. Done by Maxime Ripard.
  • Enabling of the I2C GPIO expander of the Armada 370 based Mirabox platform. Done by Grégory Clement.
  • A few updates to the support for the i.MX28 Crystalfontz boards: touchscreen and one-wire support on CFA10049. Done by Alexandre Belloni.
  • Various cleanups and improvements to the OMAP GMPC driver, done by Ezequiel Garcia.
  • Various cleanups and improvements to the Marvell Armada 370/XP IRQ controller driver, done by Thomas Petazzoni.

In detail, the contributions are:

Bootlin contributions to the 3.9 kernel

A few months ago, we published a blog post showing our contributions to the 3.8 Linux kernel. With 128 commits merged in 3.8, Bootlin was ranked as the 17th company in terms of kernel contributions.

The 3.9 kernel has been released a few weeks ago, with again a significant number of contributions from Bootlin. According to these statistics, Bootlin contributed 92 patches during the 3.9 cycle, making the company the 26th most important contributor to the Linux kernel for this release, and this time, five engineers from Bootlin contributed patches.

Among the contributions that we made:

  • Added a basic infrastructure for irqchip drivers in the drivers/irqchip directory. This directory is now used to store the drivers for the IRQ controllers of various processors.
  • Made a number of improvements to the Marvell SDIO driver, including the addition of a Device Tree binding for it, and enabled its usage on Marvell Armada 370 and Armada XP platforms, as well as converting the Marvell Kirkwood platforms to use Device Tree probing instead of legacy probing for their SDIO interface.
  • Contributed a number of improvements to support Crystalfontz i.MX28 based modules, including the Device Tree for the CFA10037 expansion board, various improvements for the CFA10049 expansion boards, and a driver for the Himax HX8357B LCD controller.
  • A large number of improvements to the support of the Allwinner ARM SoCs, most notably a pinctrl driver for those SoCs, which allows to configure the muxing of I/O pins, and a gpio driver, to use the pins as general-purpose I/Os. We also contributed the support for the Miniand Hackberry platform, based on an Allwinner SoC. This work is all done by our engineer Maxime Ripard, who is the maintainer of the Allwinner SoC support in the Linux kernel.
  • Improvements to the PCA953x driver (for I2C GPIO expanders) in order to support the PCA9505 chip, that has 40 GPIOs. This required quite some work, as the PCA953x was originally limited to chips having at most 32 GPIOs. This improvement was done in order to support the GPIO expander box provided by Globalscale for the Armada 370-based Mirabox platform.
  • We added support for the Real Time Clock on Armada 370 and Armada XP based platforms, added support for local timers on Armada XP, added support for the new Armada XP GP evaluation board.
  • We enabled support for the SPI controllers and the USB controllers on Armada 370 and Armada XP based platforms.

Our high rate of contributions is going to continue, as we already have 95 patches merged for the upcoming 3.10 kernel and have already submitted a number of patches for the 3.11 kernel.

Here are details about our contributions to the 3.9 kernel: