Buildroot Summer 2022 Hackathon

Buildroot is an easy-to-use and popular embedded Linux build system, used by many as an alternative to Yocto/OpenEmbedded. Bootlin has expertise in both build systems, and has in particular been a long time contributor to the Buildroot project. Bootlin CEO’s Thomas Petazzoni is one of the co-maintainers of the project, to which he has contributed over 5000 patches.

From July 23 to July 27, four members of the Buildroot community gathered in the sunny south of France for a 5-day long hackathon on Buildroot: Yann Morin, Romain Naour from Smile, Arnout Vandecappelle from Mind and Thomas Petazzoni from Bootlin.

The main goal of this hackathon was to reduce the backlog of patches accumulated in the project’s patchwork, the tool used in the Buildroot community to record all contributed patches and make sure all of them are handled: reviewed, accepted, or potentially rejected.

When we started the hackathon, the backlog of patches cumulated to over 410 patches, and the hackathon allowed to reduce the backlog to 150-160 patches, especially taking care of all patches contributed before the beginning of 2022. In total, over 400 patches were merged during the hackathon in the Buildroot Git repository, which obviously is more than the reduction of the backlog of patches. This is mainly due to additional patches contributed during the hackathon itself (the community has been very active at submitting new patches!) and due to the review process triggering additional ideas or rework that required more patches.

Here is a summary of the main highlights that were merged during this hackathon:

  • New package for ntpsec, a “a secure, hardened, and improved implementation of Network Time Protocol”
  • Some cleanup of the genimage configuration files to use shortcuts for common GPT partition GUIDs
  • Test cases added for the get-developers script
  • Addition of several new defconfigs for multiple RISC-V 64-bit noMMU platforms: Sipeed MAIX-Bit, Sipeed MAIXDUINO, Sipeed MAIX-Dock, Sipeed MAIX-Go and Canaan KD233, based on Canaan K210 SoC.
  • Migration of the .py to .pyc byte-compilation to use the built-in Python infrastructure instead of a custom script.
  • Addition of support for version 12 of the GCC compiler. This means that GCC 11 is now the default in Buildroot, and support for GCC 9 has been removed.
  • Many new Python packages added: python-lark, python-typeguard, python-mypy-extensions, python-typing-inspect, python-rfc3987, python-ruamel-yaml, python-pyrsistent, python-pylibfdt, python-maturin
  • Rust has been bumped to 1.62.0
  • New package for mender-connect, a daemon responsible for handling bidirectional (websocket) communication with the Mender server
  • Some fixes to the glslsandbox-player package
  • New package for OpenSC, a set of libraries and utilities to work with smart cards.
  • New package for hyperfine, a benchmark tool written in Rust. It evaluates execution time of a command passed in arguments and make a relative comparison if multiple arguments are used at the same time.
  • New package for hawktracer, a highly portable, low-overhead, configurable profiling tool built in Amazon Video for getting performance metrics from low-end devices.
  • New package for vis-network, a JS library to display dynamic, automatically organised, customizable network views
  • New package for Avocado, an automated testing suite containing tests for various subsystems.
  • New package for freeradius-server, an open source server which implements a protocol for remote user Authorization, Authentication and Accounting.
  • New package for volk, a Vector-Optimized Library of Kernels. It is a library that contains kernels of hand-written SIMD code for different mathematical operations.
  • A rework of the LTO handling: LTO support is now always enabled in GCC, and the new option BR2_ENABLE_LTO allows to request LTO to be used by packages that support it.
  • New package for the Qt 6 library, separate from the current Qt 5 package. For now, the Qt 6 package is very minimal: it only packages qt6base, and only the core of Qt, not even the GUI support is enabled. As part of this, the double-conversion and libb2 packages were added.
  • Support for configurable page size for ARM64 was added. In addition to the default 4 KB, 64 KB pages are supported. This includes some test cases that allow to validate the 64 KB ARM64 page size support in Qemu.
  • New package for clpeak, a tool that profiles OpenCL devices to find their peak capacities, together with its dependency OpenCL-CLHPP, the C++ bindings for OpenCL
  • A rework of several top-level menuconfig options: the “enable MMU” option is now part of the Target architecture menu, the Toolchain menu is now before the Build options menu, which allows the choice of the C library to be done before the choice of static vs. shared libraries. This allows the choice of static library to be made unavailable when glibc is selected, fixing a number of invalid configurations.
  • New package for GDAL, a translator library for raster and vector geospatial data formats.
  • New package for libutp, a uTorrent Transport Protocol library
  • New package for dust, an alternative written in Rust of the command “du”.
  • The C-SKY CPU architecture support was removed, as it was no longer maintained, and barely used.
  • New package for gitlab-runner, the open source project that is used to run your jobs and send the results back to GitLab
  • New package for dbus-broker, which is an alternative implementation of the D-Bus daemon, by the systemd community. It is integrated in Buildroot so that either classic D-Bus or dbus-broker can be used as the D-Bus daemon implementation.
  • New package for nerdctl, a Docker-compatible CLI for containerd, controlling runc.
  • A rework of how the udev hwdb is handled, to be consistent between systemd and eudev, and to remove useless hwdb source files from the target, as the hwdb is compiled at build time.
  • And at least 137 packages have seen their version bumped

Several other topics were looked at and discussed, but did not necessarily lead to patches already integrated. One such topic is the investigation of several issues with elf2flt, the tool used on noMMU architectures to produce binaries in the FLAT format, from an ELF binary. Another topic is the merge of the SciPy package, for which the review and testing is well advanced.

Overall, it was a very productive hackathon, and besides the massive work done on Buildroot from 9 AM to (at least) midnight each day, the participants also enjoyed lots of side discussions, embedded Linux related or not. We look forward to the next in-person gathering of the Buildroot community, on September 17/18 in Dublin, right after the Embedded Linux Conference Europe.

Updated Buildroot support for STM32MP1 platforms

Back in December 2021, we had announced the buildroot-external-st project, which is an extension of the Buildroot build system with ready-to-use configurations for the STMicroelectronics STM32MP1 platforms.

More specifically, this project is a BR2_EXTERNAL repository for Buildroot, with a number of defconfigs that allows to quickly build embedded Linux systems for the STM32MP1 Discovery Kit platforms. It’s a great way to get started with Buildroot on those platforms.

Today, we are happy to announce an updated version of this project, published under the branch st/2022.02 at https://github.com/bootlin/buildroot-external-st. This new version brings the following changes:

  • Updated to work with Buildroot 2022.02, the current LTS version of Buildroot
  • Updated to use the 4.0 “ecosystem” from ST, which means we’re using updated BSP components from ST, namely Linux 5.15, U-Boot 2021.10, TF-A 2.6 and OP-TEE 3.16
  • New defconfigs have been added to support all variants of the STM32MP157 Discovery Kits: STM32MP157A-DK1 and STM32MP157D-DK1, as well as STM32MP157C-DK2 and STM32MP157F-DK2.
  • The minimal defconfigs now use OP-TEE as BL32 instead of the minimal monitor provided by TF-A, called SP-MIN
  • The minimal defconfigs now have mdev enabled, to benefit from automatic kernel module loading
  • The demo defconfigs now have the Dropbear SSH server enabled

The document available on the Github page details how to use this work, but here is a quick start in just a few steps:

  1. Retrieve Buildroot itself, a branch containing a few patches on top of upstream 2022.02 is needed
    $ git clone -b st/2022.02 https://github.com/bootlin/buildroot.git
  2. Retrieve buildroot-external-st
    $ git clone -b st/2022.02 https://github.com/bootlin/buildroot-external-st.git
  3. Go into the Buildroot directory
    $ cd buildroot/
  4. Configure Buildroot, for example here the demo configuration for the STM32MP157F-DK2
    $ make BR2_EXTERNAL=../buildroot-external-st st_stm32mp157f_dk2_demo_defconfig
  5. Run the build
    $ make
  6. Flash the resulting SD card image available at output/images/sdcard.img and boot your board!

If you have any question or issue, feel free to use the Github issue tracker to contact us. Bootlin is an ST Authorized Partner, and can provide engineering and training services around embedded Linux on STM32MP1 platforms.

Bootlin at the Embedded Linux Conference North America 2022

Bootlin CEO Thomas Petazzoni and COO Alexandre Belloni will both be attending the next Embedded Linux Conference North America, on June 21-24 in Austin, Texas.

In addition, both Thomas and Alexandre will be speaking at the event:

  • Thomas Petazzoni will give a talk Buildroot: what’s new?, providing an update on the improvements and new features in the Buildroot build system that have been integrated over the past two years
  • Alexandre Belloni will give a talk Yocto Project Autobuilders and the SWAT Team, during which he will explain what’s happening behind in the scenes in the Yocto Project to review and validate contributions before they are integrated.

Thomas and Alexandre will also naturally be available during the event to discuss business or career opportunities, so do not hesitate to get in touch if you’re interested.

Finally, prior to the event, Thomas Petazzoni will be in the Bay Area on June 13-15, also available for meetings or discussions.

Announcing buildroot-external-st, Buildroot support for STM32MP1 platforms

STM32MP1 Discovery Kit 2Back in 2019, ST released a brand new processor family, the STM32MP1, whose members are currently based on a dual Cortex-A7 to run Linux combined with one Cortex-M4 to run bare-metal applications, together with a wide range of peripherals.

Following the release of this new platform, Bootlin ported its Embedded Linux and Yocto training courses to be available on STM32MP1, and also published a long series of tutorials showing how to use Buildroot to build an embedded Linux system on STM32MP1: part 1, part 2, part 3, part 4, part 5, part 6 and part 7.

We are happy to announce that we have partnered with ST to develop an improved support of Buildroot on STM32MP1, which is materialized by a Buildroot BR2_EXTERNAL available on Github at https://github.com/bootlin/buildroot-external-st. In Buildroot, a BR2_EXTERNAL is an extension of the core Buildroot, with additional configurations and/or packages.

This BR2_EXTERNAL tree is an extension of Buildroot 2021.02, which provides four example Buildroot configuration to easily get started on STM32MP1 platforms:

  • st_stm32mp157a_dk1, building a basic Linux system for the STM32MP1 Discovery Kit 1 platform, with a minimal Linux root filesystem
  • st_stm32mp157c_dk2, building a basic Linux system for the STM32MP1 Discovery Kit 2 platform, with a minimal Linux root filesystem
  • st_stm32mp157a_dk1_demo, building a much more featureful Linux system for the STM32MP1 Discovery Kit 1 platform, with Linux root filesystem that allows to run Qt5 applications with OpenGL acceleration on the HDMI output, that supports audio, demonstrates the usage of the Cortex-M4, uses OP-TEE, and more.
  • st_stm32mp157c_dk2_demo, building a much more featureful Linux system for the STM32MP1 Discovery Kit 2 platform, with Linux root filesystem that allows to run Qt5 applications with OpenGL acceleration on both the integrated DSI display and HDMI output, that supports audio, WiFi and Bluetooth, demonstrates the usage of the Cortex-M4, uses OP-TEE, and more.

This BR2_EXTERNAL is designed to work with Buildroot 2021.02, with only a small set of modifications, which since then have been integrated in upstream Buildroot, ensuring that STM32MP1 users can directly use upstream Buildroot for their projects.

There is extensive documentation on how to use this BR2_EXTERNAL tree as well as how to test the various features of the STM32MP1 platform: using STM32CubeProgrammer, using Device Tree generated from STM32 CubeMX, using the Cortex-M4, testing display support, using Qt5, using WiFi, using Bluetooth, using audio and using OP-TEE. We have also documented the internals of the BR2_EXTERNAL components.

This Buildroot support is using the latest software components from the recently released 3.1 BSP from ST (see release notes), so it is based on Linux 5.10, U-Boot 2020.10, TF-A 2.4 and OP-TEE 3.12. We will keep this BR2_EXTERNAL updated with newer releases of the ST BSP.

If you face any issue while using this Buildroot support for STM32MP1, you can use the issue tracker of the Github project, or use the ST community forums. Bootlin can also provide commercial support on Linux on STM32MP1 platforms, as well as training courses.

Embedded Linux Conference 2021 schedule published, 4 talks from Bootlin

The schedule for the Embedded Linux Conference 2021 has been published and features 4 talks proposed by Bootlin !

This year, the ELC will take place in Seatle but will be organised as a hybrid virtual/physical event  due to the pandemic.  As usual the ELC will have a really interesting schedule with 46 talks covering a wide range of topics: build system, kernel graphics, boot process, security, etc.

See below the details of Bootlin talks that will be presented as virtual talks.

Advanced Camera Support on Allwinner SoCs with Mainline Linux – Paul Kocialkowski, Bootlin

Capturing pixels with a camera involves a number of steps, from the ADC reading the photosites in the image sensor to the final pixel values that are ready for encode/display, with various processing and transmission taking place along the way. While simple cases put most of the heavy lifting on the image sensor’s side (through its embedded processor) and use a simple parallel bus for transmission, advanced cases require more work to be done outside of the sensor. In addition, modern high-speed transmission buses also bring-in more complexity. This talk will present how support for such an advanced use case was integrated into the mainline Linux kernel, using the Media and V4L2 APIs. It involves supporting a sensor using the raw Bayer RGB format, transmission over the MIPI CSI-2 bus as well as support for the Image Signal Processor (ISP) found on Allwinner platforms. A specific focus will be set on this ISP, with details about the features it implements as well as the internal and userspace APIs that are used to support it. The integration between all of the involved components will also be highlighted.

Talk given by Paul Kocialkowski, at 4:50 PM PDT on September 27, 2021. See this talk in the schedule.

Embedded Linux Nuggets found in Buildroot Package Eldorado

To this date, Buildroot supports more than 2,500 packages, selected for the ability to run them on embedded Linux systems. We’ve gone exploring this Eldorado, and came back with multiple nuggets of all shapes and colors. Join this playful presentation and as if you were still a new comer to the embedded Linux community, discover lesser known tools and resources that can add to the functionality of your systems or make your life as a developer easier and more fun. Whenever possible, each resource will be shown through a quick demonstration or video capture. During this talk, I’ll also open an Etherpad for all participants to share their favorite solutions with the rest of the audience, especially the ones that deserve to be better known, and could be worth supporting in Buildroot too. We will close the session by an open review and discussion based on the nuggets shared by the audience.

Michael Opdenacker

Talk given by Michael Opdenacker, at 12:00 PM PDT on September 28, 2021. See this talk in the schedule.

I3C in Tomorrow’s Design

I3C is the new bus specification by the MIPI Alliance. While being compatible with I2C devices, this bus brings a colorful set of new features such as dynamic address assignment, in-band interrupts, hot-join, master handover and many others. It was improved once again recently with the 1.1 version of the specification which brought timer based sampling synchronization and targeted reset. All this make the I3C bus a good candidate for a number of new situations compared to its I2C cousin. It is then more and more being included in new hardware designs. With this talk we would like to propose a reminder of the various components and concepts of this relatively new bus. We will then detail how it is implemented in the Linux kernel with a short guided tour in the I3C core. Since the previous talk on I3C in 2018 by Boris Brezillon, I3C has now become a reality and starts to become available in real hardware designs. This talk will recap the basics of I3C as well as add details of the 1.1 specification and improvements in the Linux support.

Miquèl Raynal

Talk given by Miquèl Raynal, at 4:00 PM PDT on September 28, 2021. See this talk in the schedule.

OP-TEE: When Linux Loses Control

OP-TEE is an open-source Trusted Execution Environment designed to be executed in a secure context as a companion to a non secure Linux system. But what happens to the peripherals control since OP-TEE can forbid the non-secure OS to access them ? When running with a TEE, Linux isn’t in charge anymore of some critical peripherals and relies on the TEE to access and configure them. There are multiple protocols and methods to access these peripherals that are supported by Linux (SCMI, PSCI, SMC). Supporting them for a SoC requires understanding the various interactions between the systems and how to modify them to fit that new control scheme. Additionally, the configuration must be passed from OP-TEE to Linux to allow a seamless integration. This talk will cover the boot process to start a secure system and the modifications needed to run Linux when OP-TEE is in charge of some peripherals. The work that has been done for a specific SoC will be described to have a tangible real-world use-case.

Clément Léger

Talk given by Clément Léger, at 12:00 PM PDT on September 29, 2021. See this talk in the schedule.