Author: Thomas Petazzoni

Thomas Petazzoni is Bootlin's co-owner and CEO. Thomas joined Bootlin in 2008 as a kernel and embedded Linux engineer, became CTO in 2013, and co-owner/CEO in 2021. More details...

Slides from the Embedded Linux Conference

Two weeks ago, the entire Bootlin engineering team (9 persons) attended the Embedded Linux Conference in San Diego. We had some really good time there, with lots of interesting talks and useful meetings and discussions.

Tim Bird opening the conferenceDiscussion between Linus Torvalds and Dirk Hohndel

In addition to attending the event, we also participated by giving 5 different talks on various topics, for which we are publishing the slides:

Boris Brezillon, the new NAND Linux subsystem maintainer, presented on Modernizing the NAND framework: The big picture.

Boris Brezillon's talk on the NAND subsystem

Antoine Ténart presented on Using DT overlays to support the C.H.I.P’s capes.

Antoine Tenart's talk on using DT overlays for the CHIP

Maxime Ripard, maintainer of the Allwinner platform support in Linux, presented on Bringing display and 3D to the C.H.I.P computer.

Maxime Ripard's talk on display and 3D for the CHIP

Alexandre Belloni and Thomas Petazzoni presented Buildroot vs. OpenEmbedded/Yocto Project: a four hands discussion.

Belloni and Petazzoni's talk on OpenEmbedded vs. Buildroot

Thomas Petazzoni presented GNU Autotools: a tutorial.

Petazzoni's tutorial on the autotools

All the other slides from the conference are available from the event page as well as from eLinux.org Wiki. All conferences have been recorded, and the videos will hopefully be posted soon by the Linux Foundation.

Bootlin engineer Boris Brezillon becomes Linux NAND subsystem maintainer

Bootlin engineer Boris Brezillon has been involved in the support for NAND flashes in the Linux kernel for quite some time. He is the author of the NAND driver for the Allwinner ARM processors, did several improvements to the NAND GPMI controller driver, has initiated a significant rework of the NAND subsystem, and is working on supporting MLC NANDs. Boris is also very active on the linux-mtd mailing list by reviewing patches from others, and making suggestions.

Hynix NAND flash

For those reasons, Boris was recently appointed by the MTD maintainer Brian Norris as a new maintainer of the NAND subsystem. NAND is considered a sub-subsystem of the MTD subsystem, and as such, Boris will be sending pull requests to Brian, who in turn is sending pull requests to Linus Torvalds. See this commit for the addition of Boris as a NAND maintainer in the MAINTAINERS file. Boris will therefore be in charge of reviewing and merging all the patches touching drivers/mtd/nand/, which consist mainly of NAND drivers. Boris has created a nand/next branch on Github, where he has already merged a number of patches that will be pushed to Brian Norris during the 4.7 merge window.

We are happy to see one of our engineers taking another position as a maintainer in the kernel community. Maxime Ripard was already a co-maintainer of the Allwinner ARM platform support, Alexandre Belloni a co-maintainer of the RTC subsystem and Atmel ARM platform support, Grégory Clement a co-maintainer of the Marvell EBU platform support, and Antoine Ténart a co-maintainer of the Annapurna Labs platform support.

Slides from Collaboration Summit talk on Linux kernel upstreaming

As we announced in a previous blog post, Bootlin CTO Thomas Petazzoni gave a talk at the Collaboration Summit 2016 covering the topic of “Upstreaming hardware support in the Linux kernel: why and how?“.

The slides of the talk are now available in PDF format.

Upstreaming hardware support in the Linux kernel: why and how?

Upstreaming hardware support in the Linux kernel: why and how?

Upstreaming hardware support in the Linux kernel: why and how?

Through this talk, we identified a number of major reasons that should encourage hardware vendors to contribute the support for their hardware to the upstream Linux kernel, and some hints on how to achieve that. Of course, within a 25 minutes time slot, it was not possible to get into the details, but hopefully the general hints we have shared, based on our significant Linux kernel upstreaming experience, have been useful for the audience.

Unfortunately, none of the talks at the Collaboration Summit were recorded, so no video will be available for this talk.

Bootlin contributions to Linux 4.5

Adelie PenguinLinus Torvalds just released Linux 4.5, for which the major new features have been described by LWN.net in three articles: part 1, part 2 and part 3. On a total of 12080 commits, Bootlin contributed 121 patches, almost exactly 1% of the total. Due to its large number of contribution by patch number, Bootlin engineer Boris Brezillon appears in the statistics of top-contributors for the 4.5 kernel in the LWN.net statistics article.

This time around, our important contributions were:

  • Addition of a driver for the Microcrystal rv1805 RTC, by Alexandre Belloni.
  • A huge number of patches touching all NAND controller drivers and the MTD subsystem, from Boris Brezillon. They are the first step of a more general rework of how NAND controllers and NAND chips are handled in the Linux kernel. As Boris explains in the cover letter, his series aims at clarifying the relationship between the mtd and nand_chip structures and hiding NAND framework internals to NAND. […]. This allows removal of some of the boilerplate code done in all NAND controller drivers, but most importantly, it unifies a bit the way NAND chip structures are instantiated.
  • On the support for the Marvell ARM processors:
    • In the mvneta networking driver (used on Armada 370, XP, 38x and soon on Armada 3700): addition of naive RSS support with per-CPU queues, configure XPS support, numerous fixes for potential race conditions.
    • Fix in the Marvell CESA driver
    • Misc improvements to the mv_xor driver for the Marvell XOR engines.
    • After four years of development the 32-bits Marvell EBU platform support is now pretty mature and the majority of patches for this platform now are improvements of existing drivers or bug fixes rather than new hardware support. Of course, the support for the 64-bits Marvell EBU platform has just started, and will require a significant number of patches and contributions to be fully supported upstream, which is an on-going effort.
  • On the support for the Atmel ARM processors:
    • Addition of the support for the L+G VInCo platform.
    • Improvement to the macb network driver to reset the PHY using a GPIO.
    • Fix Ethernet PHY issues on Atmel SAMA5D4
  • On the support for Allwinner ARM processors:
    • Implement audio capture in the sun4i audio driver.
    • Add the support for a special pin controller available on Allwinner A80.

The complete list of our contributions:

Bootlin contributing Linux kernel initial support for Annapurna Labs ARM64 Platform-on-Chip

Annapurna Labs LogoWe are happy to announce that on February 8th 2016 we submitted to the mainline Linux kernel the initial support for Annapurna Labs Alpine v2 Platform-on-Chip based on the 64-bit ARMv8 architecture.

See our patch series:

Annapurna Labs was founded in 2011 in Israel. Annapurna Labs provides 32-bit and 64-bit ARM products including chips and subsystems under the Alpine brand for the home NAS, Gateway and WiFi router equipment, see this page for details. The 32-bit version already has support in the official Linux kernel (see alpine.dtsi), and we have started to add support for the quad core 64-bit version, called Alpine v2, which brings significant performance for the home.

This is our initial contribution and we plan to follow it with additional Alpine v2 functionality in the near future.

“Porting Linux on ARM” seminar road show in France

CaptronicIn December 2015, Bootlin engineer Alexandre Belloni gave a half-day seminar “Porting Linux on ARM” in Toulouse (France) in partnership with french organization Captronic. We published the materials used for the seminar shortly after the event.

We are happy to announce that this seminar will be given in four different cities in France over the next few months:

  • In Montpellier, on April 14th from 2 PM to 6 PM. See this page for details.
  • In Clermont-Ferrand, on April 27th from 2 PM to 6 PM. See this page for details.
  • In Brive, on April 28th from 9 AM to 1 PM. See this page for details.
  • Near Chambéry, on May 25th from 9:30 AM to 5/30 PM. See this page for details.
  • Near Bordeaux, on June 2nd from 2 PM to 6 PM. See this page for details.
  • Near Nancy, on June 16th from 2 PM to 6 PM. See this page for details.

The seminar is delivered in French, and the event is free after registration. The speaker, Alexandre Belloni, has worked on porting botloaders and the Linux kernel on a number of ARM platforms (Atmel, Freescale, Texas Instruments and more) and is the Linux kernel co-maintainer for the RTC subsystem and the support of the Atmel ARM processors.

Bootlin at the Embedded Linux Conference 2016

Like every year for about 10 years, the entire Bootlin engineering team will participate to the next Embedded Linux Conference, taking place on April 4-6 in San Diego, California. For us, participating to such conferences is very important, as it allows to remain up to date with the latest developments in the embedded Linux world, create contacts with other members of the embedded Linux community, and meet the community members we already know and work with on a daily basis via the mailing lists or IRC.

Embedded Linux Conference 2016

Over the years, our engineering team has grown, and with the arrival of two more engineers on March 14, our engineering team now gathers 9 persons, all of whom are going to participate to the Embedded Linux Conference.

As usual, in addition to attending, we also proposed a number of talks, and some of them have been accepted and are visible in the conference schedule:

As usual, our talks are centered around our areas of expertise: hardware support in the Linux kernel, especially for ARM platforms, and build system related topics (Buildroot, Yocto, autotools).

We are looking forward to attending this event, and see many other talks from various speakers: the proposed schedule contains a wide range of topics, many of which look really interesting!

Bootlin speaking at the Linux Collaboration Summit

Bootlin engineers are regular speakers at the Embedded Linux Conference and Embedded Linux Conference Europe events from the Linux Foundation, to which our entire engineering team participates each year.

In 2016, for the first time, we will also be speaking at the Collaboration Summit, an invitation-only event where, as the Linux Foundation presents it, “the world’s thought leaders in open source software and collaborative development convene to share best practices and learn how to manage the largest shared technology investments of our time”.

Collaboration Summit 2016

This event will take place on March 29-31 in Lake Tahoe, California, and the event schedule has been published recently. Bootlin CTO Thomas Petazzoni will be giving a talk Upstreaming hardware support in the Linux kernel: why and how?, during which we will share our experience working with HW manufacturers to bring the support for their hardware to the upstream Linux kernel, discuss the benefits of upstreaming, and best practices to work with upstream.

With a small team of engineers, Bootlin has merged over the last few years thousands of patches in the official Linux kernel, and has several of its engineers having maintainer positions in the Linux kernel community. We are happy to take the opportunity of the Collaboration Summit to share some of our experience, and hopefully encourage and help other companies to participate upstream.

Initial support for ARM64 Marvell Armada 7K/8K platform

Two weeks ago, we submitted the initial support for the Marvell Armada 3700, which was the first ARM64 platform that Bootlin engineers contributed to the upstream Linux kernel.

Today, we submitted initial support for another Marvell ARM64 platform, the Armada 7K and Armada 8K platform. Compared to the Armada 3700, the Armada 7K and 8K are much more on the high-end side: they use a dual Cortex-A72 or a quad Cortex-A72, as opposed to the Cortex-A53 for the Armada 3700.

Marvell Armada 7KMarvell Armada 8K

The Armada 7K and 8K also use a fairly unique architecture, internally they are composed of several components:

  • One AP (Application Processor), which contains the processor itself and a few core hardware blocks. The AP used in the Armada 7K and 8K is called AP806, and is available in two configurations: dual Cortex-A72 and quad Cortex-A72.
  • One or two CP (Communication Processor), which contain most of the I/O interfaces (SATA, PCIe, Ethernet, etc.). The 7K family chips have one CP, while the 8K family chips integrate two CPs, providing two times the number of I/O interfaces available in the CP. The CP used in the 7K and 8K is called CP110.

All in all, this gives the following combinations:

  • Armada 7020, which is a dual Cortex-A72 with one CP
  • Armada 7040, which is a quad Cortex-A72 with one CP
  • Armada 8020, which is a dual Cortex-A72 with two CPs
  • Armada 8040, which is a quad Cortex-A72 with two CPs

So far, we submitted initial support only for the AP806 part of the chip, with the following patch series:

We will continue to submit more and more patches to support other features of the Armada 7K and 8K processors in the near future.

Bootlin contributes Linux support for a first ARM64 platform: Marvell Armada 3700

Marvell Armada 3700Over the last years, Bootlin has become a strong participant to the Linux ARM kernel community, with our engineers upstreaming support for numerous ARM 32 bits platforms.

Now, with ARM64 becoming more and more mainstream, our focus in 2016 will shift towards this architecture, and we’re happy to announce that we have recently contributed to the upstream Linux kernel the initial support for our first ARM64 architecture: the Marvell Armada 3700.

This new SoC from Marvell is available in single-core and dual-core Cortex-A53 configurations, and features a wide range of peripherals: 2 Gigabit Ethernet controllers, USB 3.0 and 2.0, SATA, PCIe interfaces, DMA engines for XOR acceleration, and of course the usual SPI, I2C, UART, GPIO, SDIO interfaces. For more details, see the Product Brief.

So far, we have sent a patch series adding minimal support for this platform:

  • A UART driver, since this SoC uses a new specific UART controller
  • Small changes to an AHCI driver to support SATA.
  • The Device Tree files describing the SoC and the currently available development board. So far, only the CPU, timers, UART0, USB 3.0, SATA and GIC interrupt controllers are described.

A second version of the patch series was sent a few days later, in order to address comments received during the review.

It is worth mentioning that this SoC was publicly announced in a press release on January 6 2016, and we’ve been able to send the initial support patches on February 2, 2016, less than a month later.

We’ll be progressively submitting support for all the other hardware blocks of the Armada 3700, and also be announcing soon our development efforts on several other ARM64 platforms.