However, later on we need our kernel to run as a real time task by means of RTAI, and we don't know if that is even possible with Wine/Winelib. Anybody knows if such a thing is possible?
What is RTAI? Realtiming a task in Linux is certainly possible but you need to be root to do it. I'm not sure that Wine implements this, you could have to do it using the right Linux calls. There was a thread on this last year, I think.
No, this has nothing to do with Wine per se.
RTAI is a heavily-modified linux kernel, at least in the key areas of interaction with hardware and interrupt handling.
To get "hard real time" performance from any Linux system requires (1) a hard real version of Linux (RTLinux, RTAI etc) and (2) your task runs as a special kind of process known to the RT kernel. This is hard, but not impossible, to get going.
To get "soft real time" performance, you simply need a patched linux kernel (the morton low latency patches for 2.4; nothing as good exists for 2.6), and your task needs to run with SCHED_FIFO. there are lots of people who do this already, and its not hard.
Finally, you do not need to be root to do this if you have a kernel with capabilities enabled. This is (thankfully) becoming routine in the world of linux audio, where we routinely need this ability.
Wine is just a library. It doesn't have anything to do with running real time, except inasmuch as its code is often not RT-safe and so should never be called from code that is supposed to be running RT. The same can be said of any other library that you might use.
--p