Reusable software certification smoothes the path to safety-critical embedded systems, writes Joe Wlad from LynuxWorks

The growing volume of embedded safety-critical software in avionics and other applications is threatening to create a workload overwhelming for developers and regulators alike.

The recent Federal Aviation Administration (FAA) reusable software component (RSC) software acceptance procedures provide the approach and documentation necessary for systematic reuse of software components that meet RTCA/DO-178B, and promises to create a major shift in how software code is reused in safety-critical

To meet DO-178B, it is estimated that for every line of code there will be 5 - 10 lines of tests, and for every two lines of code there will be one signature on some review form. In addition, there is normally one requirement for every 5-10 lines of code. In an extreme example, in the 1980s a one-line change to the OFP on the Space Shuttle cost nearly $1m.

Using the RSC process, standalone software components can be accepted by the FAA as meeting DO-178B objectives across hardware platforms, allowing for “portable” certification.

RSC is an important aspect of controlling software costs and improving time-to-market and quality of software systems, especially where the system needs to go through a rigorous certification process. Until today, however, no safety-critical embedded operating system (OS) had received RSC acceptance by the FAA.

With RSC approval of the LynuxWorks LynxOS-178 real-time OS, embedded systems integrators and developers can consider the OS portion of the safety-critical software code and supporting DO-178B artefacts for re-use in other system designs with other software components without the need for full recertification.

As a result, developers can reduce the time and cost of achieving FAA certification and reduce the risk involved in redevelopment across multiple safety-critical systems.

This RSC acceptance of LynuxWorks represents the first standards-based approach for software re-use in airborne systems and equipment to allow system integrators and embedded developers to re-use their existing software.

LynxOS-178 addresses the system developers’ need to meet FAA certification by providing a time, space and resource partitioned commercial off-the-shelf (COTS) OS that satisfies the objectives of the DO-178B, level A and the ARINC 653 standard as well as full conformance with the IEEE POSIX standard.

Currently, any time a systems integrator or developer wants to integrate components of any other RTOS or any previously certified DO-178B software in multiple hardware, each new hardware/software configuration or system must be recertified.

In other words, integrators and developers cannot take full advantage of the software’s existing certification across other multiple platforms, but must go through the entire certification process for each new system they build. The RSC acceptance letter from the FAA for LynxOS-178 can be used to support virtually any FAA technical standard order.

LynxOS-178 is a COTS time and space partitioned OS that fully satisfies the objectives of the DO-178B level A specification and meets requirements for integrated modular avionics developers. It delivers the security and real-time responsiveness needed for safety-critical systems and provides a low-risk path to DO-178B certification for developers to meet the technical requirements in the production of software for airborne systems.

The powerful formula of DO-178B certification and POSIX conformance allows developers to meet the most stringent requirements for real-time safety-critical applications while ensuring application portability, software reuse and interoperability between embedded systems.

Joe Wlad, director of product management at LynuxWorks

www.lynuxworks.com