At the beginning of October a Kickstarter campaign was launched to fund the development of a low-cost board based on one of the latest Marvell ARM 64-bit SoC: the Armada 3700. While being under $50, the board would allow using most of the Armada 3700 features:
We pushed the initial support of this SoC to the mainline Linux kernel 6 months ago, and it landed in Linux 4.6. There are still a number of hardware features that are not yet supported in the mainline kernel, but we are actively working on it. As an example, support for the PCIe controller was merged in Linux 4.8, released last Sunday. According to the Kickstarter page the first boards would be delivered in January 2017 and by this time we hope to have managed to push more support for this SoC to the mainline Linux kernel.
We have been working on the mainline support of the Marvell SoC for 4 years and we are glad to see at last the first board under $50 using this SoC. We hope it will help expanding the open source community around this SoC family and will bring more contributions to the Marvell EBU SoCs.
We used to keep a list of Linux friendly embedded board makers. When this page was created in the mid 2000s, this page was easy to maintain. Though more and more products were created with Linux, it was still difficult to find good hardware platforms that were supported by Linux.
So, to help community members and system makers selecting hardware for their embedded Linux projects, we compiled a first selection of board makers that were meeting the below criteria:
Offering attractive and competitive products
At least one product supported Free Software operating systems (such as Linux, eCos and NetBSD.
At least one product meeting the above requirements, with a public price (without having to register), and still available on the market.
Specifications and documentation directly available on the website (no registration required). Engineers like to study their options on their own without having to share their contact details with salespeople who would then chase them through their entire life, trying to sell inappropriate products to them.
Website with an English version.
In the beginning, this was enough to reduce the list to 10-20 entries. However, as Linux continued to increase in popularity, and as hardware platform makers started to understand the value of transparent pricing and technical documentation, the criteria were no longer sufficient to keep the list manageable.
Therefore, we added another prerequisite: at least one product supported (at least partially) in the official version of the corresponding Free Software operating system kernel. This was a rather strong requirement at first, but only such products bring a guarantee for long term community support, making it much easier to develop and maintain embedded systems. Compare this with hardware supporting only a very old and heavily patched Linux kernel, for example, which software can only be maintained by its original developers. This also reveals the ability of the hardware vendor to work with the community and share technical information with its users and developers.
Then, with the development of low-cost community boards, and chip manufacturers efforts to support their hardware in the mainline Linux kernel, the list again became difficult to maintain.
The next prerequisite we could add is the availability as Open-source hardware, allowing customers to modify the hardware according to their needs. Of course, hardware files should be available without registration.
Don’t hesitate to post comments to this page to share information about hardware which could be worth adding to this Wikipedia page!
Anyway, the good news is that Linux and Open-Source friendly hardware is now easier and easier to find than it was about 10 years back. Just have a preference for hardware that is supported in the mainline Linux kernel sources, or at least from a maker with earlier products which are already supported. A git grep -i command in the sources will help.
On June 25, 2013, Altera and some partner companies where organizing a workshop in Toulouse (where some of the Free Electrons offices are located) about the Altera SoC FPGA platform. For $99, I participated to this full-day workshop, with a small training of the hardware and software tools available for this platform, and went away with a the development kit that was used for the practical labs, the Arrow SoCKit evaluation board.
The Altera SoC FPGA platform is a single chip that combines a dual Cortex-A9 processor and a Cyclone V FPGA (other variants are available, such as single core ARM, or bigger FPGAs). Since both are integrated on the same chip, it removes the need for a complex bus between the application processor and a separate FPGA, and it provides a very high bandwidth between the processor and the FPGA to exchange data. As can be seen on the following diagram, the Arrow SocKit evaluation board has a good number of peripherals, some of them connected to the HPS side of the processor (HPS stands for Hard Processor System, which is dual Cortex-A9 and all the hard peripherals), and some others connected to the FPGA side of the processor. Specifically, the workshop was centered around playing with the LEDs and the buttons connected to the FPGA side.
The morning of the workshop was dedicated to the hardware part, using two tools: Qsys (Altera’s System Integration Tool) and Quartus II (FPGA design). The Qsys tool allows to graphically build the hardware architecture of the SoC FPGA: you can bring the Hard Processor System, and then some additional FPGA IPs and connect them together. In the examples, two PIO IPs were added to the FPGA side, one to control LEDs and the other to control buttons. All the pin muxing and the DRAM configuration also takes place in Qsys, which in the end will automatically generate numerous elements:
FPGA code to be used by Quartus (for the FPGA side)
pre-loader source code (actually modifications to U-Boot to take into account the pin muxing and the DRAM configuration)
a Device Tree for the Linux kernel (that takes into account all the peripherals enabled in the system configuration)
Once this system-level configuration is done with Qsys, Quartus is used to synthesize the FPGA side. Finally, the FPGA bitstream can be loaded into the FPGA, and using a JTAG connection and a System Console tool, one can directly read/write the registers of the FPGA IPs that have been integrated, and easily test them without having any software running. With the SOCKit evaluation board, the JTAG connection takes place through a USB to micro-USB cable, so no special hardware is needed.
The afternoon of the workshop was dedicated to the software part, obviously mostly centered on U-Boot and Linux. The pre-loader source code (actually the U-Boot SPL) is generated by the Qsys tool to take into account all the details of the system configuration, so after doing a build of U-Boot, the labs explained how to push the U-Boot binary to the board using the JTAG connection, under the DS-5 development environment (which is the development environment provided by ARM, based on Eclipse, with a special integration of Altera tools). The lab showed that you can set breakpoints, and do step by step execution of U-Boot, as one would expect. One nice thing is that the “Peripheral Registers” view in DS-5 is automatically updated according to the hardware components in the system: all the registers of the FPGA IPs we had integrated were immediately visible, and one was able to play with the LEDs and buttons directly from DS-5 through the JTAG connection. The remainder of the labs were dedicated to booting a pre-built Linux kernel, using a Device Tree generated by Qsys previously and loaded by U-Boot. Once Linux was booted, the labs were demonstrating how to play with the LEDs using /sys/class/leds/.
All in all, it was a great workshop, giving a good overview of the tools they offer and the capabilities of such platforms, I definitely recommend others to look for the other dates of this workshop and attend, it was well worth the price (dates in US, dates in Europe). I also appreciated that the amount of marketing/commercial was really reduced to the minimum. After the lunch break, there was an additional presentation by a person from Linear Technology about the power supply architecture of two boards based on this SoC FPGA processor, and it was very technical and highly informative.
As an embedded Linux developer, I’ve however found the tools to be too much based on graphical interfaces, with millions of windows and buttons to fill in, and a sensation of not really controlling which tool was doing what exactly. For example, it is a bit unclear at first which files are really your “source” files and which other files are generated. Having graphical interfaces also makes me wonder how all the build steps can be automated. It seems like version control and automated builds are not necessarily taken into account when designing those tools, but more investigation is certainly needed to get a good understanding of what those tools are doing.
On the Linux kernel side, it is worth noting that Altera has engaged into an upstreaming process for this architecture, and one can find some mainline support for this platform in arch/arm/mach-socfpga in the kernel tree. It is worth mentioning that Xilinx also has a similar architecture combining a dual Cortex-A9 and FPGA, called Zynq, which has mainline kernel support in arch/arm/mach-zynq.
And below, the front and bottom of the SoC Kit evaluation board:
Our partner ISEE is famous for their IGEPv2 board that we use in our embedded Linux course. This board is both powerful (running at 1 GHz) and featureful (on-board WiFi and Bluetooth, many connectors and expansion capabilities).
The good news is that ISEE has started to develop a new IGEPv5 board, which will be based on the new OMAP5 processor from Texas Instruments. This processor features in particular 2 ARM Cortex A15 cores running at up to 2 GHz, DDR3 RAM support, USB3, full HD 3D recording, and supporting 4 displays and cameras at the same time. Can you imagine what systems you could create with such a CPU?
If you are interested in such a board, it is still time for you to give them your inputs and expectations.
What should a perfect OMAP5 board be like? Don’t hesitate to leave your comments on this blog post. Be sure that ISEE will pay attention to them.
The success of the BeagleBoard platform, a low-cost development platform, that has greatly contributed to the success of Texas Instruments OMAP3 processor in the embedded Linux industry, seems to have inspired another processor manufacturer: ST Ericsson. They have recently unveiled Snowball, a low-cost development platform for their AP9500 processor, which features a dual Cortex A-9 ARM core and a Mali 400 GPU.
The development board is designed and produced by our partner Calao Systems, and offers the following features:
The AP9500 processor, dual Cortex-A9 and Mali 400 GPU
4 to 8 GB of e-MMC storage
1 GB of LP-DDR2 RAM
Ethernet connector, Wifi and Bluetooth
HDMI output, composite video output
USB On The Go
On-board battery to keep time
Serial port connector, JTAG connector, MiPi 34 debug connector
3-axis accelerometer, magnetometer and gyrometer, one pressure sensor
Expansion connectors to access SPI, I2C, LCD, MiPi devices, GPIO, UART, etc.
Last but not least, the board can be powered via USB (through a regular cable or through a Y one if power hungry devices like Wifi are used.)
The technical documentation page has a few more details, but at this time, they isn’t a lot of public information available about the AP9500 processor. I hope that ST Ericsson will fully understand how open source works and will soon release datasheets for the AP9500 in an open way. Interestingly, the AP9500 does not use the traditional PowerVR SGX 3D graphics core designed by Imagination Technologies and found in many other ARM processors, but instead uses the Mali graphics core, which is designed directly by ARM. It seems ARM has already open-sourced the kernel side bits of their graphic drivers, but it looks like a proprietary binary blob in userspace is still present.
A Software Development Kit variant for 165 Euros. My understanding is that the only difference between the two are the expansion connectors, present on the PDK variant but not on the SDK variant.
The board should be widely available at the end of Q2 2011, i.e around June, though at Free Electrons, we will receive our first samples by the end of March thanks to our partnership with Calao Systems. The Snowball platform is supported by the Igloo Community, which hosts mailing-lists, an IRC channel, documentation and will also provide Meego and Android builds for the Snowball in the future.
Stay tuned on this blog. As soon as we get our own boards, we will write about our experiments with them.