Interrupt sharing thing

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

Hi. A few months ago I posted here a few messages about a problem I had
sharing interrupts with serial ports. I had 2 srial ports in the main
board, and an old IO card in an ISA slot.
Well, it seems that the old io card was not able to share interrupts (
main board usually do ), so I
made a very small board with some circuitry and attched it to the io card.
Now the card shares irqs  3, 4 and 7. I tested it with serial ports and
works
fine. I have the serial.o driver with SHARE_IRQ flag set. 
What I want to know is how will the kernel behave if I assign irq 7 to
both parallel port and a serial port. The small board I made is very
flexible
by means of a set of jumpers. I can assign any irq ( 3,4 or 7) to a serial
port or the parallel port. Its fine that the serial driver is able to
share irqs. But parportpc.o and serial.o are diferent modules. How will
the irq share change the behaviour of these drivers?

If the kernel allows the features im talking about, then, we'll have a
mutch more flexible way to add hardware to our system, without
constrains, if only manufacturers did with their cards what I did with
mine.

PS: In my case performance loss is not a matter.


thank you in advance


J.A.Serralheiro