shared interrupts (newbie question)

Brian Topping (
Tue, 2 Apr 1996 19:50:52 -0700

Hi all,

Hope this isn't too much of a greenie question, but I am trying to adapt
the tulip driver to shared interrupts. The hardware setup is a Asus
P55TP4N motherboard (AMIBIOS) with a Znyx 314 (4 DEC 21040 Ethernet NICs on
the other side of a DEC 21050 PCI-PCI bridge).

Q1: Comparing to other drivers that use shared int's, all I can discern
is that they use dev->priv to pull their globals from.

Is this the only difference (besides the SA_SHIRQ flag
to request_irq())? Does the kernel automagically pick the
correct dev entry when a shared interrupt happens? (And can I
find out what file this happens in?)

Q2: The motherboard seems to be allocating different IRQ's for each
different NIC on the board. If I want to share an interrupt
between all of the NICs, do I have to somehow stop this or is
it sufficient to just fudge it in the probe routine? I know
that even though the IRQ's are reported to be different, an
interrupt on NIC[1] comes in on the same interrupt as NIC[0],
and the Znyx says that they should be on the same interrupt

Q3: If the 21050 PCI-PCI bridge is not listed in pci.h, is that
going to be a problem? (vendor ID=0x1011, device ID=0x21,
if you are interested)

THANKS!!! :-)