Re: Determining pci bus from irq

[Alan Cox <alan@lxorguk.ukuu.org.uk>]

On Maw, 2003-09-09 at 18:36, Richard B. Johnson wrote:
> Unless you've got a 'scope. If a device is interrupting often
> or if it can be made to interrupt. you can look at the pin on
> the PCI card. For some reason, on ix86, the logical "pin" is
> always "A", regardless of the device, so you only have one
> interrupt line connected to each slot. On lap-tops, there is
> often only one IRQ shared for everything IRQ9 for Compaq.

Multifunction devices may well use more than INTA. A PC does 
normally use INTA for each device and barberpole the ABCD lines
between slots

Quad ethernet cards using ABCD seem common