ARINC 653P4

This document specifies both the interface and the behavior ofthe APEX services. Behavior is specified to the extent needed todescribe behavior relevant to calling applications.

Where necessary, assumptions are made as to the support orbehavior provided by the operating system and hardware. This shouldnot be construed as a specification for the O/S or hardware.However, where the O/S or hardware does not coincide with thestated assumptions, the API behaviors specified herein may notmatch the actual behavior.

ARINC 653 is intended for use in a partitioned softwareenvironment. In order to assure a high degree of portability,aspects of the partitioned environment are discussed and assumed.However, this specification does not define the complete system,hardware or software requirements for partitioning, nor does itprovide guidance on proper implementation of partitioning and inparticular, robust partitioning. It must not be construed thatcompliance to this standard in any way assures robustpartitioning.

The main objectives of this Subset are the following:

• Achieve an execution model and O/S abstractions for a simplersoftware design than with ARINC Specification 653, Part 1.

• Simplify dynamic behavior, make it easier to characterize andenable formal methods for Worst Case Execution Time (WCET)analysis.

• Maintain portability of applications with ARINC Specification653, Part 1 (i.e., an application that is compliant to ARINCSpecification 653, Part 4 should operate in ARINC Specification653, Part 1 compliant environment).

• Downsize O/S code footprint, reduce O/S overhead, improvereal-time performance.

• Scale down O/S complexity to enable formal proof analysis.

• Reuse configuration tools from ARINC Specification 653, Part 1compliant environments.

• Reduce cost of certification.

Purpose

This document defines a Subset for the Application ProgrammingInterface (API) specified by ARINC Specification 653, Part 1,Required Services. This document is based on Supplement 3 to Part1. Based on a simpler execution model, with only one or twoprocesses, and a reduced set of services, it defines “restrictions”to the ARINC 653 Part 1 API.

The primary objective of this Specification is to define arestricted interface between the Operating System (O/S) of anavionics computer resource and the application software. Includedwithin this specification are the interface requirements betweenthe application software and the O/S and the list of services whichallow the application software to control the scheduling,communication, and status information of its internal processingelements.

This Specification defines the data exchanged statically (viaconfiguration) or dynamically (via services) as well as thebehavior of services provided by the O/S and used by theapplication. It is not the intent of this specification to dictateimplementation requirements on either the hardware or software ofthe system, nor is it intended to drive certain system levelrequirements within the system which follows this standard.

The majority of this document describes the runtime environmentfor embedded avionics software. This list of services identifiesthe minimum functionality provided to the application software andis, therefore, the industry standard interface. It is intended forthis interface to be as generic as possible, since an interfacewith too much complexity or too many system specific features isnormally not accepted over a variety of systems. The softwarespecifications of the APEX interface are High Order Language (HOL)independent, allowing systems using different compilers andlanguages to follow this interface.

Edition:

12

Published:

06/28/2012

Number of Pages:

84

File Size:

1 file , 480 KB