Another interrupt thing

["J.A.Serralheiro" <mrserra@ci.uc.pt>]

Hi. I'm trying to put to work 4 com ports in my pc. I have 2 on board,
and
bought an old Multi IO card with another 2, & a parallel port. Because the
Multi IO card is tied up to irq 3 & 4, I had to make some hardware
changes. I noticed that serial ports module, could enable IRQ_SHARE and so
instead of wiring the board to other 2 interrupt lines, i made some
hardware & added it to the board so that both ports could share the same
interrupt, which I decided to be irq line 7. This line, ( 7) is used by
the parallel port 0x378. I can disable it, but if possible I'd like to
have it enabled, and using the same irq 7. This may look a bit weird, but
I'm an electronics guy that likes to have lots of gadgets hanging on the
computer. What I really want surely has something to do with the kernel
internals. I want that both serial.o and parport_pc.o ( i mean, both the
modules for serial ports and parallel ports ) can work using the same irq
( 7 ). What are the chances to achieve that, and how. I already have
anotherparallel port on 0x278. Switching cards, more hardware changes, or
disabling ports are not options. And dont tell me that the isa bus
interrupts should NOT be shared.

Here are some facts I found:
when parport_pc configures 0x378 to work, nothing works.
when parport_pc does not, it works fine.
The problem must be a conflict between both ISR's  installed.

Any help or comment is welcome

thanks

J.A.Serralheiro