OSEK_VDX 操作系统规范2.1r1：汽车行业的实时系统标准

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"OSEK_VDX_Operating_System(OS)_V2.1.0_R1_2000.pdf" OSEK（Open System for Embedded Electronics in Cars）是一种针对汽车电子控制单元（ECU）的开放架构工业标准。它由多个部分组成，并且某些部分已经由国际标准化组织（ISO）的17356标准所涵盖。这个标准旨在促进汽车行业中软件组件的互操作性和复用性，以降低开发成本并提高系统的可靠性和安全性。 ISO 17356标准包括以下六个部分： 1. **OSEK Glossary**：这部分是ISO 17356-1的一部分，包含一个ISO风格的介绍和术语表，为后续的标准文档提供了统一的词汇和定义。 2. **OSEK Binding Specification**：基于OSEK Binding 1.4.1，ISO 17356-2详述了OSEK规范与其他系统之间的接口和兼容性要求，确保不同供应商的软件组件可以协同工作。 3. **OSEK OS**：基于OSEK OS2.2.1，ISO 17356-3定义了操作系统的具体规范，包括任务管理、调度、中断处理、内存管理等实时操作系统的核心功能。 4. **OSEK COM**：基于OSEK COM3.0.2，ISO 17356-4规定了通信子系统，允许在ECU之间进行数据交换，支持不同任务间的同步和通信。 5. **OSEK NM**：基于OSEK NM2.5.2，ISO 17356-5涵盖了网络管理，用于配置、监控和诊断网络中的节点，确保网络运行的稳定性和故障检测能力。 6. **OSEK OIL**：基于OIL 2.4.1，ISO 17356-6是OSEK配置语言，用于描述应用程序和硬件资源的映射，使得软件配置过程标准化。 OSEK/VDX Operating System Specification 2.1r1详细描述了一个实时操作系统的设计概念，该系统支持多任务处理，特别适用于汽车环境。此规格不是针对特定实现的产品描述，而是提供了一个通用框架，允许不同的制造商按照统一的规范开发各自的操作系统实现。该文档涵盖了操作系统的基本要素，如任务创建、调度策略、优先级设置、同步机制（如信号量和事件标志）、中断服务、定时器服务以及内存管理。此外，还讨论了如何通过OSEK COM子系统实现ECU之间的通信，以及如何使用OSEK NM来管理和监控网络状态。 OSEK标准为汽车行业的嵌入式软件开发提供了一套完整的体系结构和接口标准，促进了跨厂商的软件复用和互操作性，降低了开发复杂性和成本。

OSEK/VDX

Operating System

Specification 2.1r1

14 © by OSEK OSEK OS 2.1r1

• Assignment of interrupt service routines to interrupt priority levels is dependent on

implementation and hardware architecture

• For task priorities and resource ceiling-priorities bigger numbers refer to higher

priorities.

• The task’s priority is statically assigned by the user (the meaning of task priorities is

described in chapter 4.5)

Processing levels are defined for the handling of tasks and interrupt routines as a range of

consecutive values.

Processing levels Processed instance

k...m Interrupt

j Scheduler

0...i Task

Figure 3–2 Processing levels of the OSEK operating system (table)

The following rule applies for the processing level :

0<=i<j<k<=m

The operating system provides services and ensures compliance with the priority rules

mentioned above.

Please note that assignment of a priority to the scheduler is only a logical concept which can be

implemented without directly using priorities.

3.2 Conformance classes

Various requirements of the application software for the system, and various capabilities of a

specific system (e.g. processor, memory) demand different features of the operating system. In

the following description, these operating system features are described as "conformance

classes" (CC).

Conformance classes exist to support the following objectives:

• To provide convenient groups of operating system features for easier understanding and

discussion of the OSEK operating system.

• To allow partial implementations along pre-defined lines. These partial implementations may

be certified as OSEK compliant.

• To create an upgrade path from classes of lesser functionality to classes of higher

functionality with no changes to the application using OSEK related features.

The complete conformance class must be implemented to be certified. However, system

generation needs only to link those system services that are required for a specific application.

Conformance classes cannot be changed during execution.

Conformance classes are determined by the following attributes:

• Multiple requesting of task activation, as described in chapter 4.3

• Task types, as described in chapter 4.2

• Number of tasks per priority

OSEK/VDX

Operating System

Specification 2.1r1

OSEK OS 2.1r1 © by OSEK 17

4 Task management

4.1 Task concept

Complex control software can conveniently be subdivided in parts executed according to their

real-time requirements. These parts can be implemented by the means of tasks. A task provides

the framework for the execution of functions. The operating system provides concurrent and

asynchronous execution of tasks. The scheduler organises the sequence of task execution.

The OSEK operating system provides a task switching mechanism (scheduler), including an

idle mechanism. (see chapter 4.4, Task switching mechanism).Two different task concepts are

provided by the OSEK operating system:

• basic tasks

• extended tasks

Basic Tasks

Basic tasks only release the processor, if

• they terminate,

• the OSEK operating system switches to a higher-priority task, or

• interrupt occurs which cause the processor to switch to an interrupt service routine

(ISR).

Extended Tasks

Extended tasks are distinguished from basic tasks by being allowed to use the operating system

call WaitEvent, which may result in a waiting state (see chapter 6, Event mechanism, and

chapter 12.5.3.4, WaitEvent). The waiting state allows the processor to be released and to be

reassigned to a lower-priority task without the need to terminate the running extended task.

In view of the operating system, management of extended tasks is, in principle, more complex

than management of basic tasks and requires more system resources.

4.2 Task state model

The following text describes the task states and the transitions between the states for both task

types.

A task must be able to change between several states, as the processor can only execute one

instruction of a task at any time, while several tasks may be competing for the processor at the

same time. The OSEK operating system is responsible for saving and restoring task context in

conjunction with task state transitions whenever necessary.

4.2.1 Extended tasks

Extended tasks have four task states:

running In the running state, the CPU is assigned to the task, so that its instructions

can be executed. Only one task can be in this state at any point in time, while

all the other states can be adopted simultaneously by several tasks.

ready All functional prerequisites for a transition into the running state exist, and

the task only waits for allocation of the processor. The scheduler decides

which ready task is executed next.

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OSEK_VDX 操作系统规范2.1r1：汽车行业的实时系统标准

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