Multiple PCI devices on the same IRQ: kernel or driver?

[David]

Reply to mail from Mark Martin about Multiple PCI devices on the same IRQ: kernel or driver?
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> There has been a fair amount of traffic on the mailing list about Erik's
> problem.  Erik indicated that he had been advised that sharing an IRQ
> under Linux was "not a good idea".  Jon Lewis suggested that the kernel
> does a poor job of IRQ sharing but suggested hacking the tulip driver. 
> David (david@kalifornia.com) implicated the kernel when he mentioned
> that he has no trouble sharing an IRQ and credited the development
> kernels that he runs.

a few comments and questions..

i have had and am currently had fair luck sharing irqs.  to qualify this i
relate the following.

  - some of the systems i have used do NOT like sharing irqs whatsoever.
      this system would -not- run a pci dec chip nic no matter what i did.
      it did run a 3com only if the 3com was the only pci card.

  - some systems are picky.  arrange the cards in different a different
      order until you find a workable chain.

  - some systems are picky about who sits in the bus mastering slot(s)

  - some cards are picky about being in/out of the bus mastering slot

  - 2.1.xxx kernels seem to be fairing much better wrt resource sharing.

  - tulip cards don't seem to like being in a BM slot.  i rarely use a
      driver other than the tulip.c, so i've not tested the de driver w/ a
      tulip in the BM slot

now that this has been said, i'll comment.  i am currently running asus
TX-97 X and XE boards.  they are both sharing various irqs.

at one time, i was successfully sharing a tulip card, an ncr 810, and an
stb tv tuner card on the same irq.  i did have to arrange them in a
particular order.

i did notice you mentioned that bios always assigns the same irq to all. 
can you modify your bios to:

  - do manual assignment/legacy unavailability settings
  - not assign an irq to video card

i have a tulip card that is -very- stubborn.  i have gotten it to work
twice in the some 150 odd times i have tried to use it.  i have not tried
it with v.90 yet, i'll give it a try soon and see if i can share in the
misery again :S

-d
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