This is the homepage of RTAI - the RealTime Application Interface for Linux - which lets you write applications with strict timing constraints for your favorite operating system. Like Linux itself, this software is a community effort.

What is RTAI? RTAI means Real Time Application Interface. Strictly speaking, it is not a real time operating system, such as VXworks or QNX. It is based on the Linux kernel, providing the ability to make it fully pre-emptable.

RTAI is a true community project. Just download and try it out - the developers are looking forward to your comments, ideas and other help to make RTAI one of the best realtime extensions available! This website is the master resource for all kind of information about RTAI.

A new release of the official RTAI User Manual containing 2 new chapters: 3rd which covers how to work with the CVS and 5th which explains the schedulers. Chapther 4 has also some new tests described.

RTAI and the RT-Linux patent. The following statement by Eben Moglen, General Counsel of the Free Software Foundation clearifies the legal situation of RTAI users with regard to the infamous RT-Linux Patent.

Recall that RTAI schedulers allow only higher priority tasks to preempt the execution of lower priority ones. So equal priority tasks cannot preempt each other and rt_task_yield() should be used if a user needs a cooperative time slicing among equal priority tasks.

RTAI init_module does a few important things: • initializes all of its control variables and structures; • makes a copy of the idt_table and of the Linux irq handlers entry addresses; • initializes the interrupts chips management specific functions. rtai.h contains basic defines and inlined functions which performs RTAI services

In such a situation one can save the overhead of using a hard real time scheduler, e.g. those made available by RTAI or NMT-RTL (http://www.rtlinux.org/), and do all what is needed from an interrupt handler, timed by an external source or, as shown in examples available in the RTAI distribution, by the PC 8254 timer, or local APIC timers when ...

RTAI home page

The RTAI users’ mailing list is the primary communications medium for discussion of all kinds of problems and ideas. If you need help, if you want to contribute something to the project, or if you have found a bug the mailing list is the first address to contact.