[beagleboard] problem test beagleboard xm rev C

> HI
> sorry for disturb but I have some technical problem with beagleboard
> xm,
> now I triy to test user button interrupt.

Please read up on utilizing interrupts in the Linux kernel:
http://tldp.org/LDP/tlk/dd/interrupts.html
http://lwn.net/Articles/127698/

I don't believe the patch to get interrupts in userspace is included.
Without having time to read about it (because you keep pushing for a
quick answer), I believe all that really happens is that interrupts
get translated into events, though there might be some mechanism for
turning them into signals.

I suspect what all you really want is to read the event in a thread
(or even just a single threaded process). When you read the event,
the kernel will block and run other threads (and other processes)
until the event occurs (the key is pressed).

>
> Firstly I test user button by readgpio 4 and all it's OK
>
> and then I test same button with another application evtest
> /dev/inpunt/event0 and all it's OK .

evtest is a great example of how to wait on and use events from a
process (application).

>
> But after I test with evtest application the solution readgpio 4 (or
> echo 4
>> /sys/class/gpio/export ) don't working, also after reset board or
>> power
> down and power up.
>
> I don't understand, Can you help me?

If the GPIO is consumed by a kernel driver, then it can't be exposed
via the SYSFS interface. Similarly, the LEDs use up the GPIO pins, so
you wouldn't be able to export their SYSFS interface either.

Please read this part ^^^^^^^^