On Monday 24 April 2006 23:07, you wrote:
> A long time ago, I had a machine with a 3c509 card that would sometimes 

Heh, I still have this one in my server. :)

> The fake interrupt could even print out a warning if somebody returns 
> SA_HANDLED (since normally there _shouldn't_ have been any work to handle 
> for it),

Are you sure this can't race against the hardware?
Something like this:
Kernel                               Hardware
- generate fake IRQ
- enter the low level IRQ handling
                                     - hardware generates an IRQ and
                                       sets it's IRQ reason registers
                                       to "I have smthng to do"
- enter the handler and service
  the IRQ
- return SA_HANDLED

-- 
Greetings Michael.