Resarch And Implementation Of High Reliability Real-Time Embedded Operating System

Entering the 21st century, with the steady developments of new technologies, the complexity of real-time software is growing significantly. Real-time system must support on-line upgrading, which may inevitably risk introducing new bugs, therefore it will be difficult to ensure the reliability of the system even with a wide range of integrated system level tests. Meanwhile, the system peripherals tend to be open, multi-functional, and manageable intelligent devices, and the embedded applications need to be customizable and expansible for the device drivers dynamically. The security and manageability of the devices have become crucial.As a result, real-time operating system must provide a highly reliable platform with means such as reliable upgrading, fault isolation, fault avoidance and fault-tolerant to ensure the real-time software up-to-date and its reliable operation. The high reliability embedded real-time technology has become the developing trend of future real-time OS Technology.In addition, the modern real-time system is no longer an isolated system, and is often associated with the other systems. Application isolation and security are extremely important issues. In the field of avionics, the evolution of system architecture has gone through four stages: discrete, federated, integrated and highly-integrated. Integration has been encouraged for advance from the display system to the data processing, and then the sensor system. However, integration is in need of support from a new operating system.Based on ReWorks, an embedded real-time operating system developed by East China Institute of Computer Technology, this paper presents a research on the high reliability embedded real-time operating system for avionics. This paper focuses on the construction of high reliability real-time embedded operating system, mainly discusses the establishment of the virtual partitioning environment, which involoves the protection techniques for partitioning space and time domain, partition scheduling based on time window, and patition loading based on dynamic loading. On the other hand, partition itself runs an real-time operating system, which handles task management, inter-process communication, and so on.The key technologies for high reliability embedded operating system include:The space and time domain protection technology, which enables fair use of system resources by each functional domain in the real-time system, satisfies the needs for real-time processing. The system is logically partitioned, so that all tasks within each functional domain are excuted in their own partition. Patition is the excution environment for tasks, a container to excution, is also a scheduling unit for the safety cricitical kernel. Each partition has independent CPU time and memory space, and is isolated from other partitions. According to the distribution of the time windows, the safety critical kernel conducts the globle scheduling for the partitions.The blueprint for the system configuration, which describes the high reliability system by giving definitions on system resource allocations and system actions. System's security largely depends on the accuracy of a blueprint. In order to increase the openness, the blueprint is described by using the commercial data exchange language (XML language).On the basis of ReWorks, the result of this research is the design and realization of an ARCINC653 conformant high reliability embedded real-time operating system suitable for avionics.The achievements by the research are the implementation of a high reliability system with virtual partitions, enabling mutiple system functional modules to share a single CPU while functionally complementing each other, and supporting the flexibility of system configuration.Additionally, the high reliability embedded system in this paper is designed in accordance with the ARINC653 standard, not only communications between such systems comply with the standard, but also applys when such system communicating with other operating system that is ARINC653 conformant, for eample, VxWorks653 from Wind River.This paper describes the entire process of application loading, including configuration blueprint, blueprint analysis, partition loading, and so on. Health monitoring is also described in this paper, along with the failure recovering mechanisms, such as system restart, system refactoring, and so on. Hence, provides support for unified installing, running, and redeployment of the system modules in a large-scale system.