Subject: Re: Interrupt handling
To: John F. Woods <>
From: David Maxwell <>
List: current-users
Date: 11/08/1994 13:28:03
> > Does the kernel support multiple devices configured on the same interrupt?
> I'll try to give an architecture-independant answer.
  [...  Cool things about interrupts and appropriate Intel bashing deleted ...]
> That said, I believe that some devices are able to share interrupts, but
> the device has to be carefully designed to make that work (easy to poll
> for interrupt status, etc.).  A randomly chosen ISA bus board will not
> necessarily be able to make that work.  (I seem to recall there's a version
> of the COM device driver that shares interrupts.)

Yes, most multiport serial boards build it in as an effort to escape another
IBMism - (Com1-4 having separate IO addresses and IRQs) implement IRQ sharing
on a per-board basis, mostly due the the MS-DOS 'kernel' I believe. What is
the problem with polling the boards to find out who set the IRQ? Even ISA
boards? Which other systems suffer from shortage of IRQs? (Or is Intel/IBM
the only short-sighted combination around?)

							David Maxwell