This article celebrates the one-year anniversary of the Open Source Automation Development Lab, an industry group working to improve Linux for use in industrial automation. Included are retrospectives of the group's history and accomplishments, along with an outline of its agenda and ongoing activities. Enjoy . . . !

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Celebrating the Open Source Automation Development Lab's first anniversary

by Carsten Emde

Rationale

When manufacturers of industrial automation hardware and software decided to use Linux and other Open Source software components in their products, they were confronted with the necessity to make the source code available. Interestingly, they were not worrying about making sources available per se, but rather they did not want to pay for the development of a certain software component that others — possibly competitors — could use free of charge. Therefore, they wanted a mechanism that would ensure a fairer distribution of software development costs. This led to the founding of the Open Source Automation Development Lab (OSADL), which started its activities as a registered cooperative in late summer 2006.

OSADL founding members
(Click to enlarge)

One of OSADL's main activities is acting as a “purchase community.” Membership fees are used to delegate the development of Open Source software projects that the majority of members request or at least agree to. Other activities include working groups, testing laboratories, and seminars on technical and legal issues of Open Source software.

In short, OSADL was founded specifically for the automation industry with a similar idea in mind as the Open Source Development Lab (OSDL), the precursor of today's Linux Foundation. In addition, OSADL is publishing technical articles and organizing appearances at trade fairs such as SPS/IPC/Drives and Embedded World.

This article outlines OSADL's activities and achievements in its first year.

The organization

When Friedrich Wilhelm Raiffeisen founded the first cooperative banking association in Germany in 1864, he famously commented, “What is impossible for the individual, many can do.” This motto applies to the Open Source movement and OSADL, which adopted the cooperative as its organizational model. Other reasons to favor a cooperative included its democratic structures of decision-making, the absence of any hidden risk for a member, and its long and successful tradition.

The members

In addition to the eleven founding members, six new members have joined OSADL during the last year, and many others have signaled their interest. The three membership levels — Bronze, Silver, and Gold — correspond to one, two, or three voices in the General Assembly. The 17 current member companies (three Gold, one Silver member and 13 Bronze) are machine and machine tool companies, manufacturers of hardware and software for the automation industry, and open source software service providers. They employ a total of more than 50,000 employees. A continuously updated list of regular members is available on the OSADL Web site, here.

Recently, OSADL has established a special academic membership for universities and similar research institutions, which does not require a membership fee. Three universities from three different countries have already joined as academic members, and more are expected to follow soon.

The following sections summarize OSADL's most important current projects.

Real-time to the mainline Linux kernel

OSADL supports the activities to add real-time capabilities to the mainline Linux kernel. This project is known as “RT-Preempt patches;” it is maintained by Ingo Molnar and Thomas Gleixner, with support from many others.

At the Ottawa kernel summit in summer 2006, it was decided to start merging these patches gradually into mainline Linux. A year later, about 60 to 70 percent of these patches have made it into mainline Linux, and it is expected that the remaining parts will follow. Currently, 32- and 64-bit x86, PowerPC, and ARM processors are fully supported; support for high-resolution timers of MIPS processors is expected in the patches of the 2.6.24 kernel. OSADL provides support to develop, test, and improve the RT-Preempt patches.

Safety critical Linux

One of the few reasons that may still prevent an automation company from using the Linux kernel in an industrial project is the difficulty to obtain safety certification. Up to now, every individual company has had to prepare its own documentation and other material required by the local certification authorities. This would become much easier if the development and maintenance procedure of the Linux kernel and the various mechanism of quality assessment were openly documented in a form acceptable for certification. In addition, “proven in use” cases as well as reliable performance data contributed by an approved testing laboratory would be needed.

In order to provide such material and to bundle the activities towards “Safety Critical Linux,” an OSADL project was established. Professor Nicholas McGuire at the Lanzhou University was named OSADL's Safety Coordinator. McGuire will lead a related working group that is currently being formed to select, in close collaboration with Thomas Gleixner and other OSADL kernel developers, a so-called “Latest Stable” Linux kernel for the automation industry.

Certification material and the results of validation suites will be provided for these selected kernels. Currently, the latest stable real-time kernel is linux-2.6.21.6-rt21.

Upstream submission

Many Linux drivers and other kernel components — often for devices that are used in the automation industry — are maintained off-tree and are never submitted for inclusion into the mainline kernel. A developer may not have the time, the patience, or the skills to tweak the source code in such a way that it may be acceptable for upstream submission. While this may not be a problem in the short-term, in the long-run it may create much additional work, for example when internal kernel interfaces are being changed, and every off-tree module needs to be adapted separately. Furthermore, a generally available kernel module has a much broader testing platform and will probably soon be extended with new features.

In order to encourage companies to submit kernel components and to provide support for doing so, the OSADL Upstream Submission Program was launched. So far, the upstream submission of the drivers for Maxim's MX6550 and National Semiconductor's LM93 sensor chips, both part of the lm_sensors kernel subproject, have been sponsored by OSADL. Support for National Semiconductor's LM94 will follow soon.

Universal framework to access field-bus devices from application level

An OSADL working group led by Robert Schwebel (Pengutronix) and Dieter Hess (3S Smart Software Solutions) is creating a standardized layered framework to access fieldbus and other industrial I/O devices in a canonical way. First code portions and example definitions are already available and can be downloaded from the OSADL Web site.

Board support packages

A common problem of board support packages (BSPs) is that many of them can only be used to boot a system, and are not intended as a platform on which to base further development. In addition, troubleshooting is difficult, if not impossible. OSADL, therefore, has created a scale of BSP conformance levels from level 0 to level 4.

Level 0, for example, denotes a BSP that solely allows one to boot a computer board of a given target architecture, but doesn't follow any other conformance requirements. Level 2 requires, among other stipulations, that the patches follow the kernel patch rules and coding style. In addition, a level-2 BSP can be compiled with sparse check without warnings. Level 4 requires that the documented functionality of all components of the hardware platform is supported by a particular version and revision (or higher) of a released mainline kernel.

The description of all BSP conformance levels is available on the OSADL Web site. OSADL testing laboratories have been established to certify the conformance of a BSP with the requirements. When buying a computer board, the customer may ask for the OSADL BSP conformance level, which facilitates the quality assessment and comparison of BSP software from different manufacturers.

Kernel Virtual Machine and real-time capabilities of the host system

The Kernel Virtual Machine (kvm) module that Avi Kivity published in September 2006 was accepted for inclusion into the mainline Linux kernel only two months later. It provides support for hardware virtualization, e.g. for vmx (Intel's virtual machine extension) and svm (AMD's secure virtual machine).

From the very beginning, it was evident that the kvm virtualization method would become a very attractive alternative to the currently existing virtualization technologies that are mainly used in data center systems and other high-availability servers. Only recently, we learned that kvm virtualization is also very attractive for machine companies, since for the first time it allows them to establish a stable design of a machine's controlling computer system, irrespective of the introduction or discontinuation of hardware components.

In addition, virtualization allows machine companies to easily cope with computer hardware failure. Since the virtual machine does not rely on specific computer hardware, it may quickly and easily be moved to another physical hardware unit and run on it without requiring any reconfiguration.

Because of the automation industry's ever present challenge to reduce costs, the idea was quickly born to combine the often separate control computer and user interface on a single motherboard. The control computer would act a physical system and the user interface as a kvm-based virtual system. This, however, requires that running the virtual system under kvm would not interfere with the required real-time capabilities of the physical computer. A large part of the work that is required to allow the kvm module to run in an RT-Preempt patched kernel was, and will be, provided by OSADL.

Other projects and activities

Other OSADL projects focus on migration tools to port applications and drivers from other real-time systems to RT-Preempt Linux and to provide Linux support for related file systems. One of these projects is a compatibility layer that allows the use of drivers developed under the Real-Time Driver Model (RTDM) in native realtime (RT-Preempt patched) kernels. The work of Wolfgang Grandegger and the support of our member Denx Software Engineering is gratefully acknowledged.

In addition, OSADL has published a number of technical articles, such as this one about using native mainline Linux in embedded systems. When OSADL is organizing a booth on trade fairs such as SPS/IPC/Drives or Embedded World in Nuremberg, Germany, OSADL members can exhibit at the OSADL booth at no additional cost. The same holds for seminars — for example, our recent free-to-members seminar on the changes of GPL v2 to v3.

Additional services to be provided in the future

In addition to the named projects, OSADL may establish more services for its members. If required, OSADL may, for example, help its members to cope with threats that are related to patent and other legal issues.

Interested in becoming a member?

OSADL invites interested companies from all over the world to join OSADL and to share their resources, in order to create open software components for the automation industry.

For further details, visit OSADL's website, here.

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About the author — Carsten Emde is an experienced software developer with more than 15 years of experience working with embedded systems and Internet technologies. He has served as the OSADL's general manager since its founding.

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This article was originally published on LinuxDevices.com and has been donated to the open source community by QuinStreet Inc. Please visit LinuxToday.com for up-to-date news and articles about Linux and open source.