While diving through Google for AUTOSAR classic I found openOSEK.org as the automotive real-time operating system (RTOS). OSEK is a/the ISO17356 Standard implementation. Under the section “Why OSEK” the following sentences confused me:
Most of these alternatives are quite bulky and their real-time performance is not quite “real” enough.
The API of most alternatives (typically POSIX) is not ideally suited to the combination of engine synchronous … and time synchronous (asynchronous) task scheduling.
First of all it plays on same level as e.g., FreeRTOS and due to that it is not just a bare-metal support library. Due to the ISO reference: “OSEK/VDX is a preemptive multitasking operating system, with fixed pre-configured task scheduling. It is defined as a static operating system to reach an optimized usage of cpu time and hardware resources.”
OK it is a static operating system. What is that? As far as I understood it is about how libraries are linked into programs; either static or dynamic. With OSEK necessary library functions are directly in the executable binary file and can run as soon as it is loaded. Disadvantage is, that every executable contains copies of the same common library, increasing main memory and disk-space usage. Advantage is the expected faster startup- and may run-time.