Re: PCI riser cards and PCI irq routing, etc

From: Alistair John Strachan
Date: Sun Feb 18 2007 - 20:50:29 EST

On Sunday 18 February 2007 19:39, Lennart Sorensen wrote:
> > > On a PC, the BIOS is supposed to assign interrupts to devices based on
> > > those rules, since that is how the hardware must be done according to
> > > the PCI specifications.
> >
> > I set the BIOS for 'PnP OS installed'. Should I change that?
> I would NEVER do that. That actually disables the BIOS from doing
> configuration of most hardware since it really means "Microsoft wants to
> do configuration themselves and asked us to put in a setting to make the
> bios only configure drive controllers and sound cards". I know some
> people have worked towards making linux a "PnP OS" by microsoft
> standards, but whether it is entirely there or not by now I am not sure.
> Fortunately most motherboards I have ever bought come preset at 'pnp os
> installed' off, which is how I like it. I have had a number of
> problems on systems with that setting on, which went away when the
> setting was set back to off.

I think this option actually _used_ to mean whether the BIOS would _provide_
PNP services to the host OS, allowing it to detect peripherals like parallel
ports, etc. In reality, very few devices on modern PCs use or require BIOS
PNP support, and in some situations it's just annoying (for example,
disabling the parallel port on my Thinkpad has no effect because Linux just
uses PNP to redetect it).

> It might actually work better if you change that, although it may also
> just make no difference.

In my experience it just makes no difference. I strongly doubt the option has
_anything_ to do with this problem.


Final year Computer Science undergraduate.
1F2 55 South Clerk Street, Edinburgh, UK.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at