Re: Interrupt sharing thing
On 14 Aug 2001 12:40:12 +0100, J.A.Serralheiro wrote:
>
> 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.
Do you have a device that requires the interrupt on the lpt ports? My
understanding is that linux doesn't use the irq for just a printer.
--mike
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