how to process shared interrupt?

[qiao <at80401@yahoo.com>]

Victor Yodaiken wrote:
> 
> My belief is that shared interrupts are not very 
useful for RT systems - does anyone
> think otherwise?
> 
> If an interrupt is shared between RT and non RT 
devices, the RT driver must do
> 
> catch_interrupt:
>         examine my device
>         if interrupt is mine
>                 do regular handling
>         else
>                 pend interrupt for Linux/BSD
>                 find the interrupting non-RT device
>                 clear device interrupt
>                 re-enable interrupts from this source

How to do this four step?
is there a function that pass the interrupt to non-RT linux kernel? 

> 
> The key point is that the RT driver needs to look at 
all non-RT devices
> in order to clear the interrupt source.
> This is not too hard, but it seems not very RT.

I think ,in RT interrupt handler , check if the interrupt is it's own ,
if not ,pass it to non-RT linux to do other jobs, this will be almost RT.

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