Green Hills has achieved certification of conformance of its Integrity-178 Time-Variant Unified Multi Processing (tuMP) real-time operating system (RTOS) to the Future Airborne Capability Environment (FACE) Technical Standard edition 3.0.
The certification covers the Safety Base profile and the Security profile for safety-certifiable software in the Integrity-178 tuMP RTOS, and underscores the commitment of Green Hills for certification to open standards, company officials say.
Version 3.0 of the FACE Technical Standard represents a major improvement over the prior version 2.1.1 in that it addresses the use of multicore processors in safety-critical applications.
The technical standard now requires any operating system segment (OSS) that claims support for multicore partitions to meet ARINC-653 Part 1 Supplement 4, including the requirement for multicore operation as defined in Section 2: "Multiple processes within a partition scheduled to execute concurrently on different processor cores." In ARINC-653, each application is called a partition and has its own memory space.
Asymmetric multi-processing (AMP), the simplest software architecture in a multicore-based system, is not sufficient to meet the requirements of Supplement 4. Integrity-178 tuMP meets the requirements of ARINC-653 Supplement 4, and it does so with the availability of Bound Multi-Processing (BMP) in addition to AMP and Symmetric Multi-Processing (SMP).
By definition, BMP is an enhanced and restricted form of SMP that can statically bind an application's ARINC-653 processes (i.e., tasks) to a specific set of cores, allowing the system architect to more tightly control the concurrent operation of several cores.
Integrity-178 tuMP enables system developers to bind ARINC-653 processes within an application to a core using an API or using the system configuration file. In addition, Integrity-178 tuMP meets the ARINC-653 Part 2 Supplement 3 requirements for SMP operation.
Integrity-178 tuMP supports combinations of AMP, SMP, and BMP in a time-partitioned manner on a multicore processor. Meeting worst-case execution times (WCET) while several cores are executing concurrently can be very challenging no matter the choice of AMP, SMP, or BMP.
Contention from several cores trying to access a given shared resource, such as memory or I/O, can create interference between cores. Certification authorities have emphasized their concerns about such interference by including objectives for interference identification, mitigation, and verification in the CAST-32A position paper.
As a multicore IMA operating system, Integrity-178 tuMP includes a capable multicore scheduler and support for bandwidth allocation and management of shared processor resource access.
The supported bandwidth management technique emulates a high-rate hardware-based approach to ensure continuous allocation enforcement. These capabilities greatly lower integration and certification risk, while also enabling the integrator to manage significant software retest costs that would occur when a software application changes or is added.
Without operating system features and support for bandwidth management of the shared multicore resources, such software changes would require analysis and retest of all other potential concurrent applications. When considering the following: (a) development, integration and certification risks, (b) future application growth requirements, and (c) long-term system sustainment objectives, Integrity-178 tuMP is the ideal multicore high-assurance RTOS solution.
For more information contact Green Hills Software online at www.ghs.com.
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