Re: 3 PCI NIC's on OpenBSD 2.6(x86) sharing IRQ's

[Hal Snyder <hal@vailsys.com>]

Nick Holland <nhollan@home.com> writes:

...

> However, you most certainly CAN share interrupts on the PCI bus.
> That was one of the points of the PCI bus (personally, while they
> were at it, I wish they would have ganged up another IRQ controller,
> but they didn't ask me).
...

Thanks for the clarification. One addition: I have a system in which
sharing PCI IRQs causes slowdowns and lockups, on recent hardware.
This is with an Intel 440BX SMP-capable MB with only one CPU
installed, in which a quad Adaptec Tulip card can't share IRQs with
external fxp and lmc devices.

Each of the four Ethernet (de) ports on the quad card is automatically
assigned a separate IRQ. The two ports that don't share IRQs work
fine. The two ports that share IRQs with the fxp and lmc devices can't
be used - bringing them up makes the server unusable.

The box is in production so we haven't had time to chase this one any
further for awhile.


(BTW this holds when running NetBSD on the same configuration.)