Real-time UNIX executables
Real-time operating systems - Examples of industrial operating systems

As mentioned in [R 8 050], two main approaches have been followed in real-time developments around UNIX^®:

1) one in line with the POSIX^® standard: this consists of enriching the standard with services adapted to real time;

2) the other, later, in the wake of LINUX^®. The latter can again be divided into two approaches:

• that of making the kernel pre-emptive, thus providing real-time reaction capabilities for applications,

• using a real-time kernel that considers LINUX^® as one of its low-priority tasks. The kernel takes control of interrupts and the processor.