Hello

I recently heard of real time Linux (RT Patch and Xenomai), but now
very little of it. I hope, someone can make some points clear to me.
At the first place it seems to me that when working Xenomai, I have
to use some special API - not Linux ordinary one. Is it so ? And what
about so called RT Patch ?
Furthermore, is it possible to write mixed - Linux and Xenomai API
in one application, even if Linux application is GUI ?
And (for the moment) the last one - why should anyone use ordinary
Linux (kernel) if one can have, for example, Xenomai and that way
Linux + real time in addition ?

Regards

A generalization but for most the only real time applications used are video / music processing and playback. Typically the stock kernel is good enough and the occasional flicker etc, is only a minor annoyance. The default kernel is optimized for total system throughput vs real time applications. Real time applications are robotics, process control etc where timing is extremely critical.

I am not familiar with Xenomai. Yes basically RTAI is two parts i.e. the kernel patch and the programming API.

Kind of a sore spot in linux. The mainstream tried to put real time into the mix but it was basically failed. You simply have to have an entire OS dedicated to real time. At best now we get what may be termed "near realtime" option.

If you need real time then you have to buy it or use qnx.