The fact is, incredible as it may seem, the Linux OS can be used as an RTOS; that is, a hard real-time-capable RTOS. The project started out as the brainchild of Thomas Gleixner (of Linutronix), who wanted to port Linux to become an RTOS.
Again, this is really the beauty of the open source model and Linux; being open source, interested, and motivated people take Linux (or other projects) as a starting point and build upon it, often coming up with significantly new and useful products.
A few points to note regarding this project are as follows:
- Modifying the Linux kernel to become an RTOS is a necessarily invasive procedure; Linus Torvalds, the de facto Linux boss, does not want this code in the upstream (vanilla) Linux kernel. Thus, the real-time Linux kernel project lives as a patch series (on kernel.org itself; see the links in the Further reading...