Re: irq sharing not permitted - comedi's or RTLinux/RTAI's limitation?

On Fri, May 16, 2003 at 11:21:54AM +0900, 小笠原 卓 wrote:
> Dear comedi users,
> 
>   As I read the comedi source code, I discovered that comedi does not allow
> a realtime interrupt handler to share irq with non-realtime handlers. Is it
> that it is impossible to share interrupt under RTLinux/RTAI, or it is
> comedi's limitation?

In a real-time system, Comedi requires that it can easily switch
an interrupt between real-time and non-real-time.  Thus, if you
tried to share the interrupt with any other driver (including
another Comedi driver), there would be times when one interrupt
is real-time and one non-real-time.

When the code was written, RTAI and RTLinux could not support
shared interrupts, but things may have changed.

Comedi doesn't allow _any_ sharing if RTAI or RTLinux support is
enabled mainly because of stability and code sanity reasons.  And
since it's a really bad idea to share real-time interrupts anyway,
I don't see much incentive to fix it.



dave...

Received on 2003-05-16Z04:51:15