Triggering UserCode from KernelModule (IRQ)

["M. Koehrer" <mathias_koehrer@arcor.de>]

Hi all!

I am currently evaluting the RT_PREEMPT kernel as a replacement for a Xenomai based real time application.
(Intel Core2Duo PCs).
So far, everything works really fine and the performance is about the same as with Xenomai.
Great work!

However, I have one question:
I have a PCI hardware I/O board that exchanges data with the user mode 
directly (by using mmap), this works fine.
However, there is one operation mode that uses interrupts to signal incoming data.
The interrupt handler is realized as a tiny kernel module (that one that provides also 
the mmap for the user mode application).
Now I am not sure how the signalling of the IRQ from kernel to user mode could be realized 
best (in terms of low latency).

The "classical" approach for this task is to provide a character driver with a .poll file operation.
In Xenomai I could use a semaphore that was accessible from kernel and user space for this.
What is the best way in the RT_PREEMPT "world"? 

Thanks a lot for all feedback on this question.

Regards

Mathias


-- 
Mathias Koehrer
mathias_koehrer@arcor.de


Arcor.de Gaming Area - kostenfrei daddeln bis der Arzt kommt!
Jetzt checken und aus über 80 Spielen wählen!
http://www.arcor.de/footer-gaming/
--
To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html