POSIX I/II

The blessings of the POSIX standards have fallen on GNU/Linux - as much as these standards can be painful for programmers and system designers, they have the benefit of allow clean catagorizations of systems, and they describe a clear profile of what is required to programm and operate them. This is a major demand in industry, as evaluation of an OS is a complex and timer-consuming task, so POSIX I cleanly defining the programming paradigma and POSIX II (not so cleanly) defining the operator interface, simplify these first steps.

The RTLinux API is a POSIX PSE 51 based threads API, provides a subset of POSIX interface targeted specifically at minimum realtime systems. As the POSIX threads are widly in use, moving to RTLinux is simplified greatly. The PSE 51 standard complience not only simplifies the programing task but also allows to resort to a well established knowledge base during the design phaas. RTLinux provides the folowing sumary of POSIX functions to the programer:

• Time related functions
• Basic p_thread functions
• synchronisation primitives (mutex,semaphors)
• POSIX condition variables
• Non-portable POSIX extensions. These rtlinux specific extension, that simplify your life

If one is familiar with POSIX threads then it should be simple to move on to the real-time capabilities that RTLinux provides, this not only is a efficiency question but naturally a well sepcified and commonly used API improves security. This improvment is due to the potential pitfalls of POSIX threads being well documented which increases the ability to evaluate the security implications of a programming descision.