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

[Diana Eichert <deichert@wrench.com>]

Ahh, isn't it great supporting an architecture that steadfastly maintains
it's backwards compatibility.  The original 8-bit bus PC's only had
interupts 1-8.  When IBM created the AT, they daisy-chained 8 more
interupts on INT 2.  So really you only added 7 more interupts as 2/9 were
shared.

diana

On Thu, 16 Nov 2000, Seth Arnold wrote:

> * Steve Williams <steve@genie96.com> [001116 16:37]:
> > Humm... I haven't done hardware since back in the "old" days, when it
> > was critical that nothing share IRQ's.
> 
> > fxp0 at pci0 dev 13 function 0 "Intel 82557" rev 0x05: irq 11, address ...
> > fxp1 at pci0 dev 15 function 0 "Intel 82557" rev 0x05: irq 9, address ...
> > fxp2 at pci0 dev 17 function 0 "Intel 82557" rev 0x08: irq 11, address ...
> 
> Hmm. I seem to recall that IRQ 9 was used for 'cascade', with IRQ 2.
> (This thinking is from the "old" days as well, maybe this has changed
> since then.)