Bootlin training courses for beginning of 2021

It’s the beginning of 2021, and Bootlin’s offering of online training courses continues. We have dates available for our 5 training courses, at an affordable cost, and with the same quality characteristics of all Bootlin courses: trainers with proven in-field experience, fully open-source training materials and worldwide recognized training contents.

Here are the dates of our upcoming sessions:

See our training page for more details about all our training courses!

Videos and slides of Bootlin’s talks at Live Embedded Event 2020

Yesterday, Bootlin co-organized and participated to the first edition of Live Embedded Event, a new online conference dedicated to embedded systems topics. In addition to co-organizing the event, we also gave four different talks at this conference, and we are happy to share the slides and videos of our talks.

Introduction video

The following video was presented during the introduction keynote of the event, where each sponsor and co-organizer could say a few words.

An overview of the Linux kernel and user-space graphics stack

Talk given by Bootlin engineer Paul Kocialkowski, slides available in PDF.

ASoC: Supporting Audio on an Embedded Board

Talk given by Bootlin engineer Alexandre Belloni, slides available in PDF.

Embedded Linux “from scratch” in 45 minutes…on RISC-V

Talk given by Bootlin founder and CEO Michael Opdenacker, slides available in PDF.

Device Tree: hardware description for everybody!

Talk given by Bootlin CTO Thomas Petazzoni, slides available in PDF.

4 talks from Bootlin at Live Embedded Event, December 3

As we announced back in October, Bootlin has participated to the organization of a new online conference around embedded systems: Live Embedded Event, which will take place on December 3. The registration is totally free, and the event will propose 4 tracks throughout the day, covering a wide range of topics. We encourage you to register and participate to the event!

Bootlin is not only co-organizing the event, but also has 4 talks that have been accepted:

  • An overview of the Linux and user-space graphics stack, by Paul Kocialkowski, Bootlin’s multimedia expert and author of our Linux Graphics training course. Talk abstract: Graphics with the Linux kernel is often perceived as a haystack, composed of many components that have complex interactions with eachother. While this is not always far from the truth, this talk will try to provide a clear overview of the different pieces in the stack and what their individual role is. Throughout the presentation, various APIs, protocols and software implementations will be demystified, covering both display and render aspects. This includes topics such as DRM, Wayland, Xorg, OpenGL, Mesa and more!
  • Embedded Linux from scratch in 45 minutes… on RISC-V, by Michael Opdenacker, Bootlin’s founder and CEO. Talk abstract: Join and discover how to build your own embedded Linux system completely from scratch. You will build your own toolchain, bootloader and kernel, this time on the Risc-V open Instruction Set Architecture, that you will run through a system emulated by QEMU. You will also build a minimal root filesystem by yourself thanks to the BusyBox project. You will finish by controlling the system through a tiny webserver. The approach will be to provide only the files that are strictly necessary. That’s all the interest of embedded Linux: you can really control and understand everything that runs on your system, and see how simple the system can be. That’s much easier than trying to understand how a GNU/Linux system works from a distribution as complex as Debian!
  • ASoC: audio on an embedded board, by Alexandre Belloni, Bootlin’s audio expert, Linux kernel and Yocto trainer, as well as kernel maintainer. Talk abstract: ASoC, which stands for ALSA System on Chip, is a Linux kernel subsystem created to provide better ALSA support for system-on-chip and portable audio codecs. It allows to reuse codec drivers across multiple architectures and provides an API to integrate them with the SoC audio interface. This talk will present the typical hardware architecture of audio devices on embedded platforms, how to integrate the audio codec and processor audio interface using device tree. Examples, common issues and debugging tips will also be discussed.
  • Device Tree: hardware description for everybody!, by Thomas Petazzoni, Bootlin’s CTO and co-maintainer of Buildroot. Talk abstract: The Device Tree has been adopted for the ARM 32-bit Linux kernel support almost a decade ago, and since then, its usage has expanded to many other CPU architectures in Linux, as well as bootloaders such as U-Boot and Barebox. Even though Device Tree is no longer a new thing, developers coming into the embedded Linux world often struggle to understand what Device Trees are, what is their syntax, how they interact with the Linux kernel device drivers, what Device Tree bindings are, and more. This talk will provide an introduction to the Device Tree, to jump start new developers in using this description language that is now ubiquitous in the vast majority of embedded Linux projects.

Note that we are aware of limitations of the platform that was chosen for the online conference: the details of the talks, and details about sponsors are only visible for people who registered. This is unfortunate, but we discovered this when it was too late to change the platform, together with a few other limitations. Let’s say this is a first edition, and regardless of those limitations, the selection of talks and contents is very promising!

Videos and slides from Bootlin talks at Embedded Linux Conference Europe 2020

The Embedded Linux Conference Europe took place online last week. While we definitely missed the experience of an in-person event, we strongly participated to this conference with no less than 7 talks on various topics showing Bootlin expertise in different fields: Linux kernel development in networking, multimedia and storage, but also build systems and tooling. We’re happy to be publishing now the slides and videos of our talks.

From the camera sensor to the user: the journey of a video frame, Maxime Chevallier

Download the slides: PDF, source.

OpenEmbedded and Yocto Project best practices, Alexandre Belloni

Download the slides: PDF, source.

Supporting hardware-accelerated video encoding with mainline Linux, Paul Kocialkowski

Download the slides: PDF, source.

Building embedded Debian/Ubuntu systems with ELBE, Köry Maincent

Download the slides: PDF, source.

Understand ECC support for NAND flash devices in Linux, Miquèl Raynal

Download the slides: PDF, source.

Using Visual Studio Code for Embedded Linux Development, Michael Opdenacker

Download the slides: PDF, source.

Precision Time Protocol (PTP) and packet timestamping in Linux, Antoine Ténart

Download the slides: PDF, source.

Live Embedded Event: a new online conference

Live Embedded EventIn these times of COVID19, pretty much all of the existing conferences have moved to an online format. For example, the Embedded Linux Conference Europe is going to take place next week, online, and Bootlin will significantly contribute to the event with no less than 7 talks on a wide range of topics.

But this trend for online conferences has also spurred the creation of new events. And specifically, we’re happy to announce the creation of a new conference oriented towards our favorite topic of embedded systems: Live Embedded Event. It will take place online on December 3 and will have a broader range of topics covered than ELC typically has, as Live Embedded Event is open to non-Linux embedded topics, hardware platform and interfaces discussions, and more.

The event is mainly organized by four French companies specialized in embedded systems, and we expect the contents to be a mix of talks in English and in French. Speaking of contents, the Call For Papers is open until November 10, so you can have the chance to share your knowledge about embedded topics, show your expertise, and meet new users and customers. And of course, you can also simply register as an attendee: the event is free !

Important links:

Upcoming online training courses in November/December 2020

The online training courses that we started earlier this year continue to have a good success, and as our sessions scheduled for September/October are now completed or full, we are happy to announce our next set of dates for November/December:

All courses are taught by experienced Bootlin engineers, who are not just trainers: they in fact spend most of their time working on engineering projects for our customers, and share their experience through these training courses. The above courses will be taught by Michael Opdenacker, Alexandre Belloni, Maxime Chevallier, Paul Kocialkowski and Thomas Petazzoni.

Note that in addition to those public training courses, we can upon request organize dedicated online training courses, to match the needs, schedule and availability of our customers. Do not hesitate to contact us for any question.

Bootlin toolchains 2020.08 released

Bootlin toolchainsWe are happy to announce a new release of the freely available cross-compilation toolchains we provide at toolchains.bootlin.com, version 2020.08-1.

Here are the main changes compared to our previous 2020.02 release:

  • Bleeding edge toolchains are now using: gcc 10.2, binutils 2.34, gdb 9.2, kernel headers 5.4, glibc 2.31, musl 1.2.0, uclibc-ng 1.0.34
  • Stable toolchains are using: gcc 9.3, binutils 2.33, gdb 8.3, kernel headers 4.9, glibc 2.31, musl 1.2.0, uclibc-ng 1.0.34
  • Fortran support has been enabled in all tolchains
  • Several new CPU architecture variants are supported, each with a new toolchain
  • Boot testing in Qemu was added for PowerPC64 E5500, NIOSII and m68k MCF5208.

In addition, it is worth mentioning that all those Bootlin toolchains are now directly accessible from Buildroot: make menuconfig shows the Bootlin toolchains available for the current selected CPU architecture, and Buildroot is able to automatically download and use the toolchain. This feature will be available starting from Buildroot 2020.11:

Thanks again to the entire Buildroot community, and especially Romain Naour, for all the fixes and improvements related to toolchain support that make this project possible. In the next weeks, we hope to be able to deliver further updated bleeding-edge toolchains, with glibc 2.32 and binutils 2.35. Stay tuned!

If you face any issue, or need additional features in those toolchains, do not hesitate to report an issue in our issue tracker.

Bootlin at the Embedded Linux Conference Europe 2020

Embedded Linux Conference Europe 2020The schedule for the next Embedded Linux Conference Europe has been recently published, and Bootlin will once again be strongly present at this (virtual) event by giving a number of presentations. The registration for ELC-E is open, and due to the virtual nature of the event, the registration cost is only $50, which makes is accessible to pretty much everybody.

  • From the Camera Sensor to the User, the Journey of a Video Frame. In this talk, Bootlin engineer Maxime Chevallier will share his experience working in the Video4Linux subsystem, implementing support for the Rockchip camera interface controller, and a PAL/NTSC decoder used as the input source. Talk on Monday October 26 at 18:30 GMT.
  • Yocto Project and OpenEmbedded: A Collection of Best Practices. In this talk, Bootlin engineer, and Yocto Project expert and trainer Alexandre Belloni will share his experience of using Yocto Project and OpenEmbedded through a collection of best practices. There are indeed numerous ways of using OpenEmbedded and the Yocto Project, but some ways and solutions are better than others! Talk on Tuesday October 27 at 13:00 GMT.
  • Building Embedded Debian and Ubuntu Systems with ELBE. In this talk, Köry Maincent will share his experience using the ELBE build system, which can be used to automate the process of creating embedded Linux systems based on Debian or Ubuntu. Köry has contributed to ELBE the support for building Ubuntu systems, and has used ELBE on two different projects. This is an interesting alternative to the traditional cross-compilation approach taken by Yocto Project, OpenEmbedded or Buildroot. Talk on Tuesday October 27 at 15:15 GMT.
  • Using Visual Studio Code for Embedded Development. In this talk, Michael Opdenacker will share his experiments of using VS Code for embedded Linux development, which extensions are available to help navigate in the code, build and debug code, from kernel-space and user-space. Talk on Tuesday October 27 at 17:15 GMT.
  • Precision Time Protocol (PTP) and Packet Timestamping in Linux. Antoine Ténart has implemented PTP support in both an Ethernet switch driver, and an Ethernet PHY driver, both in the upstream Linux kernel. He will share his experience about PTP, its support in Linux, and its offloading at the MAC and PHY level. Talk on Tuesday October 27 at 19:30 GMT.
  • Supporting Hardware-Accelerated Video Encoding with Mainline. After working on the HW-accelerated video decoding on Allwinner platforms as part of our crowdfunded effort, Paul Kocialkowski recently worked on HW-accelerated video encoding on Rockchip platforms. In this talk, he will share the issues encountered, and what needs to be resolved to create a useful kernel to userspace interface to properly support stateless video encoders. Talk on Wednesday October 28 at 16:15 GMT.
  • Understand ECC Support for NAND Flash Devices in Linux. Miquèl Raynal, the Linux kernel NAND subsystem maintainer, has recently worked on improving support for various strategies to handle ECC for NAND flash devices. He will share some background information on ECC, why they are needed, how and where ECC are typically handled, and how the Linux kernel deals with the different possibilities. Talk on Wednesday October 28 at 18:30 GMT.

In addition to contributing talks, Bootlin CTO Thomas Petazzoni is also a member of the ELC-E program committee: he reviewed, ranked all talk submitted for the conference and participated with the rest of the committee to the selection of the talks that are now scheduled for the event.

Even though we once again won’t have the chance to meet our fellow members of the embedded Linux community in person, we look forward to attending a set of great talks, and have interesting discussions during the Q&A and through the instant messaging platform that will be available around the conference.

Bootlin contributes SquashFS support to U-Boot

SquashFS is a very popular read-only compressed root filesystem, widely used in embedded systems. It has been supported in the Linux kernel for many years, but so far the U-Boot bootloader did not have support for SquashFS, so it was not possible to load a kernel image or a Device Tree Blob from a SquashFS filesystem in U-Boot.

Between February 2020 and August 2020, João Marcos Costa from the ENSICAEN engineering school, has worked at Bootlin as an intern. João’s internship goal was specifically to implement and contribute to U-Boot the support for the SquashFS filesystem. We are happy to announce that João’s effort has now completed, as the support for SquashFS is now in upstream U-Boot. It can be found in fs/squashfs/ in the U-Boot source code.

More specifically, João’s contributions have been:

In addition to those contributions already merged, João has also submitted for inclusion the support for LZO and ZSTD decompression support.

Practically speaking, this SquashFS support works very much like the support for other filesystems. At build time, you need to enable the CONFIG_FS_SQUASHFS option for the SquashFS driver itself, and CONFIG_CMD_SQUASHFS for the SquashFS U-Boot commands. Once enabled, in U-Boot, you get:

=> sqfsls     
sqfsls - List files in directory. Default: root (/).
 
Usage:
sqfsls  [] [directory]
    - list files from 'dev' on 'interface' in 'directory'
 
=> sqfsload 
sqfsload - load binary file from a SquashFS filesystem
 
Usage:
sqfsload  [ [ [ [bytes [pos]]]]]
    - Load binary file 'filename' from 'dev' on 'interface'
      to address 'addr' from SquashFS filesystem.
      'pos' gives the file position to start loading from.
      If 'pos' is omitted, 0 is used. 'pos' requires 'bytes'.
      'bytes' gives the size to load. If 'bytes' is 0 or omitted,
      the load stops on end of file.
      If either 'pos' or 'bytes' are not aligned to
      ARCH_DMA_MINALIGN then a misaligned buffer warning will
      be printed and performance will suffer for the load.

sqfsls is obviously used to list files, here the list of files from a typical Linux root filesystem:

=> sqfsls mmc 0:1
            bin/
            boot/
            dev/
            etc/
            lib/
    <SYM>   lib32
    <SYM>   linuxrc
            media/
            mnt/
            opt/
            proc/
            root/
            run/
            sbin/
            sys/
            tmp/
            usr/
            var/
 
2 file(s), 16 dir(s)

And then you can use sqfsload to load files, which we illustrate here by loading a Linux kernel image and Device Tree blob, and booting this kernel:

=> sqfsload mmc 0:1 $kernel_addr_r /boot/zImage
6160384 bytes read in 433 ms (13.6 MiB/s)
=> sqfsload mmc 0:1 0x81000000 /boot/am335x-boneblack.dtb
40817 bytes read in 11 ms (3.5 MiB/s)
=> setenv bootargs console=ttyO0,115200n8
=> bootz $kernel_addr_r - 0x81000000
## Flattened Device Tree blob at 81000000
   Booting using the fdt blob at 0x81000000
   Loading Device Tree to 8fff3000, end 8fffff70 ... OK
 
Starting kernel ...
 
[    0.000000] Booting Linux on physical CPU 0x0
[    0.000000] Linux version 4.19.79 (joaomcosta@joaomcosta-Latitude-E7470) (gcc version 7.3.1 20180425 [linaro-7.3-2018.05 revision d29120a424ecfbc167ef90065c0eeb7f91977701] (Linaro GCC 7.3-2018.05)) #1 SMP Fri May 29 18:26:39 CEST 2020
[    0.000000] CPU: ARMv7 Processor [413fc082] revision 2 (ARMv7), cr=10c5387d

Of course, the SquashFS driver is still fresh, and there is a chance that more extensive and widespread testing will uncover a few bugs or limitations, which we’re sure the broader U-Boot community will help address. Overall, we’re really happy to have contributed this new functionality to U-Boot, it will be useful for our projects, and we hope it will be useful to many others in the embedded Linux community!

Linux 5.8 released: Bootlin contributions

Linux 5.8 was released recently. See our usual resources for a good coverage of the highlights of this new release: KernelNewbies page, LWN.net article on the first part of the merge window, LWN.net article on the second part of the merge window.

On our side, we contributed a total of 155 commits to Linux 5.8, which makes Bootlin the 19th contributing company by number of commits according to Linux Kernel Patch Statistic. The highlights of our contributions are:

  • Miquèl Raynal contributed a completely new NAND controller driver: the arasan-nand-controller driver, used on Xilinx platforms.
  • In the MTD subsystem, Miquèl Raynal, as one of the co-maintainers, made a substantial number of contributions: cleanups in the nandsim driver, drop of the nand_release() API, support in the NAND core for the specificities of the arasan-nand-controller driver in terms of ECC handling (we will soon publish a blog post on this topic!)
  • On the support of Atmel/Microchip platforms
    • Alexandre Belloni migrated the SAMA5D3, AT91SAM9N12, AT91RM9200 and AT91SAM9G45 Device Tree files to use the new clock DT bindings
    • Grégory Clement modified the atmel_usba_udc USB device controller driver to no longer require describing all USB endpoints in the Device Tree, since they are always the same for a given SoC.
  • Grégory Clement contributed a number of improvements and fixes for the n_gsm line discipline driver, which allows to multiplex an UART used to communicate with a GSM modem. These improvements and fixes allowed the n_gsm driver to be fully stable for one of our customers.
  • In the RTC subsystem, Alexandre Belloni (maintainer of that subsystem) did a number of small improvements to various RTC drivers.
  • Antoine Ténart has done a number of improvements in the support for Microchip/Microsemi networking products: improvements to the mscc-miim MDIO driver, improvements to the MSCC Ocelot Ethernet switch driver, improvements to the MSCC Ethernet PHY Driver.

Also, several Bootlin engineers are maintainers of various areas of the Linux kernel:

  • Miquèl Raynal, as the NAND maintainer and MTD co-maintainer, reviewed and merged 57 patches from other contributors
  • Alexandre Belloni, as the RTC maintainer and Microchip platform support co-maintainer, reviewed and merged 54 patches from other contributors
  • Grégory Clement, as the Marvell EBU platform support co-maintainer, reviewed and merged 13 patches from other contributors

Here is the complete list of our contributions: