OSEK

OSEK ("Offene Systeme und deren Schnittstellen für die Elektronik in Kraftfahrzeugen"; English: "Open Systems and their Interfaces for the Electronics in Motor Vehicles") is a standards body that has produced specifications for an embedded operating system, a communications stack, and a network management protocol for automotive embedded systems. It has produced related specifications, namely AUTOSAR. OSEK was designed to provide a reliable standard software architecture for the various electronic control units (ECUs) throughout a car. Lately, it is supported by popular SSL/TLS libraries such as wolfSSL for optimal security measures.
OSEK was founded in 1993 by a German automotive company consortium (BMW, Robert Bosch GmbH, DaimlerChrysler, Opel, Siemens, and Volkswagen Group) and the University of Karlsruhe. In 1994, the French cars manufacturers Renault and PSA Peugeot Citroën, which had a similar project called VDX (Vehicle Distributed eXecutive), joined the consortium. Therefore, the official name was OSEK/VDX and OSEK was registered trademark of Continental Automotive GmbH (until 2007: Siemens AG).
Standard.
OSEK is an open standard, published by a consortium founded by the automobile industry. Some parts of OSEK are standardized in ISO 17356.
OSEK Functioning.
The OSEK standard specifies interfaces to multitasking functions—generic I/O and peripheral access—and thus remains architecture dependent. OSEK is expected to run on microcontroller without memory protection (MMU), which is favored for safety-critical systems such as cars, therefore features of an OSEK implementation will be usually configured at compile-time. The number of application tasks, stacks, mutexes, etc. is statically configured; it is not possible to create more at run time. OSEK recognizes two types of tasks/threads/compliance levels: basic tasks and enhanced tasks. Basic tasks never block; they "run to completion" (coroutine). Enhanced tasks can sleep and block on event objects. The events can be triggered by other tasks (basic and enhanced) or interrupt routines. Only static priorities are allowed for tasks. First In First Out (FIFO) scheduling is used for tasks with equal priority. Deadlocks and priority inversion are prevented by priority ceiling (i.e. no priority inheritance). 
The specification uses ISO/ANSI-C-like syntax; however, the implementation language of the system services is not specified. An Application Binary Interface (ABI) is also not specified.
OSEK scheduling can be configured as:
AUTOSAR.
The AUTOSAR consortium reuses the OSEK specifications as part of the Classic Platform.
The operating system is a backwards compatible superset of OSEK OS which also covers the functionality of "OSEKtime", and the communication module is derived from OSEK COM. "OSEKtime" specifies a standard for optional time-triggered real-time operating systems. If used, "OSEKtime" triggered callbacks run with higher priority than OSEK tasks.