DOCSLIB.ORG

Safety-Critical Software Development for Integrated Modular Avionics

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Safety-Critical Software Development for Integrated Modular Avionics white paper Safety-Critical Software Development for Integrated Modular Avionics Paul Parkinson Senior Systems Architect, Wind River Larry Kinnan Senior Engineering Specialist, Aerospace & Defense, Wind River Introduction Table of Contents Many avionics systems have been successfully developed using custom hardware and software. However, in recent Introduction ........................................................................1 years, the full life-cycle costs of customized systems have Application Development with Wind River’s forced original equipment manufacturers (OEMs) to consider VxWorks 653 Platform ........................................................2 the use of COTS-based systems. At the same time, there has Spatial Partitioning .........................................................2 been a noticeable migration away from federated architec- tures, where each individual subsystem performs a dedicated Temporal Partitioning .....................................................4 function toward generic computing platforms that can be Priority Inversion, Priority Inheritance, and used in multiple types of applications and, in some cases, run Priority Ceilings ..................................................................5 multiple applications concurrently. This approach, known as ARINC 653 Application Development ................................5 Integrated Modular Avionics (IMA), results in fewer subsys- tems, reduced weight, less power consumption, and less Heterogeneous Application Support .................................6 platform redundancy. A number of civil and military research System Configuration .........................................................6 programs have sought to define IMA architectures, and while Health Monitoring System and Restarts.............................7 they differ in their approaches, they share the same high- level objectives: Tools for Safety-Critical Systems Development .................8 • Common processing subsystems: These should allow Security Considerations for Networked IMA multiple applications to share and reuse the same Systems ..............................................................................8 computing resources. This results in a reduced number Safety Considerations for IMA Systems .............................9 of subsystems that need to be deployed and more efficient use of system resources, leaving space for Summary ........................................................................... 10 future expansion. References ........................................................................ 10 • Software abstraction: This should isolate the application About the Authors ............................................................ 10 not only from the underlying bus architecture but also About Wind River ............................................................. 10 from the underlying hardware architecture. This enhances portability of applications between different platforms and also enables the introduction of new hardware to replace obsolete architectures. • Maximize reuse: An IMA architecture should allow for reuse of legacy code. This reduces development time while affording the developer a method of redeploying This technical paper presents recent trends in the develop- existing applications without extensive modifications. ment of safety-critical avionics systems. It discusses the • Cost of change: An IMA architecture should reduce the emergence of Integrated Modular Avionics (IMA) architec- cost of change since it facilitates reuse and lowers retest tures and standards and the resulting impact on the develop- costs because it simplifies the impact analysis by ment of a commercial off-the-shelf (COTS) RTOS that is decoupling the constituent pieces of the platform that standards-compliant. execute on the same processor. IMA also facilitates support for applications that have The following sections consider the technical requirements ever-increasing levels of functionality, including the interac- for an integrated device software platform to support IMA tions between complex applications, such as head-up applications and show how VxWorks 653 Platform (see Figure displays, map display systems, and weather radar displays. 1), fulfils these requirements—in particular within the context of ARINC 653 application development. Although a number of IMA architectures and standards has emerged, the ACR Specification1 and ARINC Specification 6532 appear to have the widest adoption in the avionics Application Development with Wind River’s community. The ACR Specification addresses architectural VxWorks 653 Platform considerations, whereas ARINC Specification 653 defines at a The ACR Specification defines two important concepts high level an instance of a software implementation for an widely used in IMA: spatial partitioning and temporal IMA architecture. These and other IMA standards place new partitioning. demands on the software architecture, especially the RTOS implementation provided by the COTS supplier. Wind River Spatial Partitioning has specifically addressed these needs by developing the Spatial partitioning defines the isolation requirements for VxWorks 653 Platform3, which is being employed by the C-130 multiple applications running concurrently on the same Avionics Modernization Program and 767 Tanker4. Boeing has computing platform, also known as a module. In this model, chosen to use Wind River’s VxWorks 653 Platform for the applications running in an IMA partition must not be able to development of the Boeing 787 Dreamliner Common Core deprive each other of shared application resources or those System (CCS)5. Other Wind River customers, including EADS6, provided by the RTOS kernel. This is most often achieved are using the platform to develop avionics systems and through the use of different virtual memory contexts en- safety-critical applications. forced by the processor’s memory management unit (MMU). Eclipse Framework Workbench Editor Compiler System Viewer Development Suite Port Monitor CPU Monitor Qualified Partition Project Debugger Verocel AdaCore GNAT Pro Interpeak Software Partners Certification Services Ada Compiler Certifiable Stack DO178B Level A Certification Material ARINC 653 API VxWorks API POSIX API Run-Time Components COIL MPOS VxWorks 653 Virtutech Simulation Environment Hardware Partners COTS Boards, Semiconductor Architectures Training and Training and Installation Platform Customization Professional Services System Design Hardware/Software Integration Design Services Figure 1: Wind River’s VxWorks 653 Platform 2 | Safety-Critical Software Development for Integrated Modular Avionics App 1 App 2 App 3 App 4 Partition OS Partition OS Partition OS Partition OS Module OS ARINC Ports ARINC Scheduler Processor Figure 2: VxWorks 653 RTOS Architecture These contexts are referred to as partitions in ARINC 653. • The partition OS is implemented using the VxWorks Each partition contains an application with its own heap for microkernel and provides scheduling and resource dynamic memory allocation and a stack for the application’s management within a partition. Communication with the processes (the ARINC 653 term for a context of execution). module OS occurs through a private message-passing These requirements affect the design and implementation of interface to ensure robustness. The partition OS also the RTOS kernel and language run-time system. For example, provides the ARINC 653 APEX (application/executive) VxWorks 5.5 uses a shared virtual address space for applica- interfaces for use by applications. tions and provides basic support through the MMU to This architecture, which represents the virtual machine prevent accidental or malicious access to program code by approach as described in “Partitioning in Avionics Architec- errant applications, without incurring the performance tures: Requirements, Mechanisms and Assurance”7, provides overhead of a full process model. VxWorks 6.x and VxWorks a means of fulfilling the requirements of ARINC 653, while 653 provide an environment that uses the MMU to enforce providing a flexible, extensible framework not easily achieved separate contexts. with a monolithic kernel implementation or UNIX-like However, in an IMA environment, memory protection alone implementations. Within the framework, individual partitions would not prevent an errant application running in a partition are implemented using memory-protected containers into from consuming system resources, which might have a which processes, objects, and resources can be placed, with detrimental effect on an application running in another partitioning enforced by the MMU (virtual machines). Each partition. This can have serious consequences where multiple partition has its own stack and local heap, which cannot be applications of differing levels of criticality are running on the usurped by applications running in other partitions. The same processor. This problem cannot be resolved through partitions also prevent interference from errant memory the use of a full process model alone; instead it requires the accesses by applications running in other partitions. development of an RTOS that specifically addresses the Figure 2 shows the conceptual implementation of the needs of IMA. The VxWorks 653 operating system was VxWorks 653 architecture. The RTOS features the ability to designed specifically for this purpose and supports the have a single, shared partition OS library (shared read-only ARINC 653 model in the implementation
Load more

Recommended publications
  • Software Model Checking of ARINC-653 Flight Code with MCP Sarah J
    Software Model Checking of ARINC-653 Flight Code with MCP Sarah J. Thompson Guillaume Brat SGT Inc., NASA Ames Research Center CMU, NASA Ames Research Center MS269-1, Moffett Field, California MS-269-1, Moffett Field, California [email protected] [email protected] Arnaud Venet SGT Inc., NASA Ames Research Center MS269-1, Moffett Field, California [email protected] Abstract The ARINC-653 standard defines a common interface for Integrated Modular Avionics (IMA) code. In particular, ARINC-653 Part 1 specifies a process- and partition-management API that is analogous to POSIX threads, but with certain extensions and restrictions intended to support the implementation of high reliability flight code. MCP is a software model checker, developed at NASA Ames, that provides capabilities for model checking C and C++ source code. In this paper, we present recent work aimed at implementing extensions to MCP that support ARINC-653, and we discuss the challenges and opportunities that consequentially arise. Providing support for ARINC-653’s time and space partitioning is nontrivial, though there are implicit benefits for partial order reduction possible as a consequence of the API’s strict interprocess communication policy. 1 Introduction NASA missions are becoming increasingly complex, and, more and more of this complexity is imple- mented in software. In 1977, the flight software for the Voyager mission amounted to only 3000 lines. Twenty years later, the software for Cassini had grown by a factor of ten, and more strikingly, the soft- ware for the Mars Path Finder mission amounted to 160 KLOCs (thousands of lines of code).
    [Show full text]
  • Communications for Integrated Modular Avionics
    Communications for Integrated Modular Avionics Richard L. Alena [email protected] John P. Ossenfort IV, SAIC Kenneth I. Laws, QSS Andre Goforth NASA Ames Research Center Moffett Field, CA 94035 Fernando Figueroa, NASA Stennis Space Center TABLE OF CONTENTS Abstract—The aerospace industry has been adopting avionics architectures to take advantage of advances in computer engineering. Integrated Modular Avionics (IMA), 1. INTRODUCTION ..................................................... 1 as described in ARINC 653, distributes functional modules 2. INTEGRATED MODULAR AVIONICS...................... 2 into a robust configuration interconnected with a “virtual 3. NETWORKS FOR AEROSPACE ............................... 4 backplane” data communications network. Each avionics 4. MISSION COMPUTER DESIGN............................... 8 module’s function is defined in software compliant with the 5. LAB EVALUATION............................................... 12 APEX Application Program Interface. The Avionics Full- 6. CONCLUSIONS..................................................... 16 Duplex Ethernet (AFDX) network replaces the point-to- REFERENCES........................................................... 17 point connections used in previous distributed systems with BIOGRAPHY ............................................................ 18 “virtual links”. This network creates a command and data path between avionics modules with the software and 1. INTRODUCTION network defining the active virtual links over an integrated physical network.
    [Show full text]
  • Avionics Applications on a Time-Predictable Chip-Multiprocessor
    Avionics Applications on a Time-predictable Chip-Multiprocessor Andre´ Rocha and Claudio´ Silva Rasmus Bo Sørensen, Jens Sparsø, and Martin Schoeberl GMV Department of Applied Mathematics and Computer Science Lisbon, Portugal Technical University of Denmark Email: [andre.rocha, claudio.silva]@gmv.com Email: [rboso, jspa, masca]@dtu.dk Abstract—Avionics applications need to be certified for The demonstrators were ported to the T-CREST platform the highest criticality standard. This certification includes using its compiler tool-chain and analysis tools. The demon- schedulability analysis and worst-case execution time (WCET) strators validate the T-CREST platform. Part of the exercise, analysis. WCET analysis is only possible when the software is written to be WCET analyzable and when the platform is however, is to evaluate the added value of the platform. The time-predictable. In this paper we present prototype avionics platform shall enable application developers to determine the applications that have been ported to the time-predictable WCET of their applications more precisely or more easily. T-CREST platform. The applications are WCET analyzable, Therefore, we compare the T-CREST platform with a well- and T-CREST is supported by the aiT WCET analyzer. This established platform in the avionics domain. combination allows us to provide WCET bounds of avionic tasks, even when executing on a multicore processor. The T-CREST platform was evaluated with the aid of the following three real-world avionic applications: (1) an Airlines Operational Centre (AOC), (2) a Crew Alerting I. INTRODUCTION System (CAS), and (3) an I/O Partition (IOP). We chose The mission of the T-CREST project [1], [2] is to develop T-CREST as platform for avionics applications as this is and build a multicore processor that is time-predictable and currently the only multicore processor where static WCET easy to analyze for the worst-case execution time (WCET).
    [Show full text]
  • WIND RIVER Vxworks 653 PLATFORM 2.4 and 2.5
    WIND RIVER VxWORKS 653 PLATFORM 2.4 AND 2.5 TABLE OF CONTENTS RTCA DO-178C Certification Evidence .......................................... 2 VxWorks 653 Platform Benefits ................................................. 2 VxWorks 653 Runtime Components ............................................ 3 VxWorks 653 Module OS ................................................... 4 Partition Management ..................................................... 4 Partition Scheduling ....................................................... 4 Partition Operating System ................................................. 4 COIL .................................................................... 5 APEX Application Support .................................................. 5 FACE Technical Reference 2.0 and 2.1 Support ................................ 5 Inter-partition Communication ............................................... 6 Intra-partition Communication ............................................... 6 Health Monitor ........................................................... 6 Wind River Workbench ..................................................... 7 Included Runtime Products .................................................. 12 Wind River DO-178C Network Stack ......................................... 12 Wind River Highly Reliable File System ....................................... 12 Technical Specifications ..................................................... 12 Supported Target Architectures ...........................................
    [Show full text]
  • Towards a Real-Time Component Framework for Software Health Management
    Institute for Software Integrated Systems Vanderbilt University Nashville, Tennessee, 37203 Towards a Real-time Component Framework for Software Health Management Abhishek Dubey , Gabor Karsai , Robert Kereskenyi , Nagabhushan Mahadevan TECHNICAL REPORT ISIS-09-111 November, 2009 Towards a Real-time Component Framework for Software Health Management Abhishek Dubey Gabor Karsai Robert Kereskenyi Nagabhushan Mahadevan Institute for Software Integrated Systems, Vanderbilt University, Nashville, TN 37203, USA Abstract— The complexity of software in systems like aerospace industry, that deals with detecting anomalies, di- aerospace vehicles has reached the point where new techniques agnosing failure sources, and prognosticating future failures are needed to ensure system dependability. Such techniques in complex systems, like aerospace vehicles. While System include a novel direction called ‘Software Health Management’ (SHM) that extends classic software fault tolerance with tech- Health Management has been developed for physical (hard- niques borrowed from System Health Management. In this ware) systems, it provides interesting systems engineering paper the initial steps towards building a SHM approach are techniques for other fields like embedded software systems. described that combine component-based software construction The use of System Health Management techniques for with hard real-time operating system platforms. Specifically, embedded software systems points beyond the capabilities the paper discusses how the CORBA Component Model could be combined with the ARINC-653 platform services and the provided by the SFT techniques and can potentially in- lessons learned from this experiment. The results point towards crease a system’s dependability. This new direction is called both extending the CCM as well as revising the ARINC-653. Software Health Management (SHM) [4].
    [Show full text]
  • ARINC-653 Inter-Partition Communications and the Ravenscar Profile
    ARINC-653 Inter-partition Communications and the Ravenscar Profile Jorge Garrido Juan Zamorano Juan A. de la Puente Abstract The ARINC-653 standard is often used to build mixed-criticality systems, using a partitioned archi­ tecture. Inter-partition communication is carried out by means of a message-passing mechanism based on ports. The standard includes an API for Ada, but the implementation semantics of operation ports is not fully defined. Furthermore, the API was defined for the Ada 95 standard, and therefore does not take into account the enhancements to the real-time features of the language that have been incorporated in the 2005 and 2013 standards, most notably the Ravenscar profile. This paper is aimed at clarifying the implementation of ARINC communication ports in Ada and the Ravenscar profile. ARINC communi­ cation ports are analysed, and their compatibility with the Ravenscar profile is assessed. A new API that can be used with the profile is defined, and a pilot implementation is introduced. 1 Introduction Partitioning is a convenient approach for developing mixed-criticality systems on a single hardware plat­ form. Under this approach, a system is divided into a set of logical partitions, which are isolated from each other both in the temporal and spatial domains. Subsystems with different levels of criticaliry are allocated to different partitions, and failures in low-criticality components cannot propagate to high-criticality ones. Critical subsystems can thus be certified in isolation to the required level, provided that the partitioning ker­ nel is also certified to that level, but the validation of lower-criticality subsystems can be greatly simplified.
    [Show full text]
  • High-Assurance Separation Kernels: a Survey on Formal Methods
    1 High-Assurance Separation Kernels: A Survey on Formal Methods Yongwang Zhao, Beihang University, China David Sanan´ , Nanyang Technological University, Singapore Fuyuan Zhang, Nanyang Technological University, Singapore Yang Liu, Nanyang Technological University, Singapore Separation kernels provide temporal/spatial separation and controlled information flow to their hosted applications. They are introduced to decouple the analysis of applications in partitions from the analysis of the kernel itself. More than 20 implementations of separation kernels have been developed and widely applied in critical domains, e.g., avionics/aerospace, military/defense, and medical devices. Formal methods are mandated by the security/safety certification of separation kernels and have been carried out since this concept emerged. However, this field lacks a survey to systematically study, compare, and analyze related work. On the other hand, high-assurance separation kernels by formal methods still face big challenges. In this paper, an analytical framework is first proposed to clarify the functionalities, implementations, properties and stan- dards, and formal methods application of separation kernels. Based on the proposed analytical framework, a taxonomy is designed according to formal methods application, functionalities, and properties of separation kernels. Research works in the literature are then categorized and overviewed by the taxonomy. In accordance with the analytical framework, a compre- hensive analysis and discussion of related work are presented.
    [Show full text]
  • ARINC-653 Inter-Partition Communications and the Ravenscar Profile∗
    ARINC-653 Inter-partition Communications and the Ravenscar Profile∗ Jorge Garrido Juan Zamorano Juan A. de la Puente [email protected] jzamora@datsi.fi.upm.es [email protected] Universidad Politecnica´ de Madrid (UPM), Spain Abstract The ARINC-653 standard is often used to build mixed-criticality systems, using a partitioned archi- tecture. Inter-partition communication is carried out by means of a message-passing mechanism based on ports. The standard includes an API for Ada, but the implementation semantics of operation ports is not fully defined. Furthermore, the API was defined for the Ada 95 standard, and therefore does not take into account the enhancements to the real-time features of the language that have been incorporated in the 2005 and 2013 standards, most notably the Ravenscar profile. This paper is aimed at clarifying the implementation of ARINC communication ports in Ada and the Ravenscar profile. ARINC communi- cation ports are analysed, and their compatibility with the Ravenscar profile is assessed. A new API that can be used with the profile is defined, and a pilot implementation is introduced. 1 Introduction Partitioning is a convenient approach for developing mixed-criticality systems on a single hardware plat- form. Under this approach, a system is divided into a set of logical partitions, which are isolated from each other both in the temporal and spatial domains. Subsystems with different levels of criticality are allocated to different partitions, and failures in low-criticality components cannot propagate to high-criticality ones. Critical subsystems can thus be certified in isolation to the required level, provided that the partitioning ker- nel is also certified to that level, but the validation of lower-criticality subsystems can be greatly simplified.
    [Show full text]
  • And Space-Partitioned Architecture for the Next Generation of Space Vehicle Avionics
    Building a Time- and Space-Partitioned Architecture for the Next Generation of Space Vehicle Avionics Jos´e Rufino, Jo˜ao Craveiro, and Paulo Verissimo University of Lisbon, Faculty of Sciences, LaSIGE [email protected], [email protected], [email protected] Abstract. Future space systems require innovative computing system architectures, on account of their size, weight, power consumption, cost, safety and maintainability requisites. The AIR (ARINC 653 in Space Real-Time Operating System) architecture answers the interest of the space industry, especially the European Space Agency, in transitioning to the flexible and safe approach of having onboard functions of different criticalities share hardware resources, while being functionally separated in logical containers (partitions). Partitions are separated in the time and space domains. In this paper we present the evolution of the AIR architecture, from its initial ideas to the current state of the art. We describe the research we are currently performing on AIR, which aims to obtain an industrial-grade product for future space systems, and lay the foundations for further work. 1 Introduction Space systems of the future demand for innovative embedded computing system architectures, meeting requirements of different natures. These systems must obey to strict dependability and real-time requirements. Reduced size, weight and power consumption (SWaP), along with low wiring complexity, are also crucial requirements both for safety reasons and to decrease the overall cost of a mission. A modular approach to software enabling component reuse among the different space missions also benefits the cost factor. At the same time, such an approach allows independent validation and verification of components, thus easing the software certification process.
    [Show full text]
  • Model-Based Development of ARINC 653 Using UML and Sysml Andreas Korff, Atego – OMG RT Workshop, Paris, 18.04.2012
    Model-based development of ARINC 653 using UML and SysML Andreas Korff, Atego – OMG RT Workshop, Paris, 18.04.2012 © 2011 Atego. All Rights Reserved. 1 Agenda Motivation of Integrated Modular Systems Modelling Notation Standards UML and SysML Applying UML and SysML to IMS ARINC 653 Using Models to support ARINC 653 Conclusion © 2011 Atego. All Rights Reserved. 2 Motivation of Integrated Modular Systems Integrated Modular Systems (or IMA) aim to Minimize Life Cycle Costs Enhance Mission and Operational Performance Allow greater flexibility and re-use in Development and Maintenance Existing standards for IMS ARINC 653 – for implementing IMS concepts onto RTOSes Stanag 4626/EN 4660 – to de-couple Avionics HW and SW © 2011 Atego . All Rights Reserved. 3 Federated Architectures (shown with UML) Broad range of possible problems: Any failure effects everything Scheduling sensitive to any change Difficult to maintain: Obsolecence One change effects again everything Re-Use? © 2011 Atego. All Rights Reserved. 4 A closer Look on Federated Architectures On Closer inspection, logical ‘wrappers’ appear that perform specific functions. These can be interpreted as ‘layers’ in a Federated Architecture Physical Interface Layer Central Data Formatting Layer Controller Data Processing Layer © 2011 Atego. All Rights Reserved. 5 From Federated to a Layered Architecture In an IMS layered architecture each layer has a clearly defined responsibility, interface and is as important as each of the other layers Federated Architecture Stanag 4626/EN 4660 (ASAAC) {maps for logic} Data Processing Layer Application Layer {maps for scheduling} {maps} Data Formating Layer Operating System Layer Physical Interface Lacer Module Support Layer © 2011 Atego.
    [Show full text]
  • Studying on ARINC653 Partition Run-Time Scheduling and Simulation
    World Academy of Science, Engineering and Technology International Journal of Computer and Systems Engineering Vol:6, No:11, 2012 Studying on ARINC653 Partition Run-time Scheduling and Simulation Dongliang Wang, Jun Han, Dianfu Ma, and Xianqi Zhao generation respecting the requirement specification from the Abstract—Avionics software is safe-critical embedded software models, which greatly speeding the development of the system and its architecture is evolving from traditional federated architectures and assuring high reliability of such system. to Integrated Modular Avionics (IMA) to improve resource usability. And with the rapid development of aviation technology, ARINC 653 (Avionics Application Standard Software Interface) is a computer technology and microelectronics technology, modern software specification for space and time partitioning in Safety-critical avionics Real-time operating systems. Arinc653 uses two-level avionics architecture has gradually evolved from the traditional scheduling strategies, but current modeling tools only apply to simple federated architecture to the integrated modular avionics problems of Arinc653 two-level scheduling, which only contain time system structure (IMA)[4]. property. In avionics industry, we are always manually allocating IMA integrated all the subsystems on a common computer tasks and calculating the timing table of a real-time system to ensure platform, so as to greatly reuse various hardware resources. But it’s running as we design. In this paper we represent an automatically this potentially reduces the error control of functions. In order generating strategy which applies to the two scheduling problems with dependent constraints in Arinc653 partition run-time environment. It to introduce the error isolation as which in the federated provides the functionality of automatic generation from the task and architecture into IMA, the concept of partition is introduced in partition models to scheduling policy through allocating the tasks to [5].
    [Show full text]
  • IVV on Orions ARINC 653 Flight Software Architecture100913
    IV&V on Orion’s ARINC 653 Flight Software Architecture Adelbert Lagoy and Todd A. Gauer Agenda • ARINC 653/DO 178 background • Advantages to a 653 FSW architecture – Development – V&V – Maintenance • Available COTS 653 systems • The impact of the selection of a ARINC 653 approach on baseline documentation – Alignment and misalignment of ARINC 653 to NASA documentation • IV&V impacts from application of 653 approach – Architecture verification impacts – Requirements validation impacts – FSW code verification impacts – Potential recertification impacts • Other impacts (adverse impacts) – “overhead” from 653 – Static partition definitions – COTS OS opacity • Orion IV&V Experience ARINC 653/DO 178 background ARINC 653 • The Aeronautical Radio, Incorporated (ARINC) specification ARINC 653 is a software time and space partitioning standard for Real Time Operating Systems (RTOSs). • The ARINC 653 standard supports Integrated Modular Avionics (IMA) architecture allowing appropriate integration of avionics software of differing levels within a single hardware device. • ARINC 653 provides a level of fault protected operation. – Faults within a partition should not stop other partitions from executing. • Metaphor – ARINC 653 compliant system’s partitions are like “virtual flight computers” within the flight computer. Metaphor – ARINC 653 Conventional Monolithic System ARINC 653 System with 4 Partitions Memory Memory Time Time • ARINC 653 splits the available processor time and space into partitions (partitions do not need to be the same size). • When we talk “partition” in this discussion you can substitute “virtual flight computer” if that is helpful. ARINC 653/DO 178 background ARINC 653 • Each partition is assured of its allocated processing time and memory – Lockup, freeze, endless loop, overrun, etc within one partition will not prevent another partition from operating.
    [Show full text]