[Rtai] running an infinite loop RTAI task

[Alex Ivanov]

On Sat, 27 Sep 2008 mantegazza at aero.polimi.it wrote:
>
> Meanwhile I checked it all in kernel space, nothing changes. I can confirm
> that also on my machine a never ending loop on the reserved CPU, using
> isolcpus only, leads to a lock of other Linux activities. Since no
> interrupts is there I've still to understand what Linux tries to use on
> it.

I've never done any real kernel debugging before. Is there a way to trace
where it is locking?

Also, perhaps we can ask RTLinux guys about this, since it works just fine
there. Is anyone on friendly terms with Victor of FSMlabs? Additionally, I
am traveling to Monta Vista conference in San Francisco next week, maybe
I could find out something about it there. Definitely will be able to
try the same code there on Monta Vista Linux.

I have installed a fresh 64-bit RTAI system, 2.6.23 kernel and everything
is exactly the same: code runs, but the systems eventually gets into a
locked state. Same story with the printks as well, the messages are
getting buffered and then printed all at once after I stop the code.

One other question: is there a way to return control to Linux other than
wait_period call? I tried shed_yield but that changed nothing. I am
thinking that perhaps we can fix this problem by returning the CPU back to
Linux for a microsecond or two.

Alex