Re: [PATCH] parport_pc.c PnP BIOS sanity check

H. Peter Anvin
2001-08-08T21:58:45Z

Followup to: <E15UV8M-0005SE-00@the-village.bc.nu>
By author: Alan Cox <alan@lxorguk.ukuu.org.uk>
In newsgroup: linux.dev.kernel
>
> > The following would seem to be required to protect against
> > the case in which PnP BIOS reports an IRQ of 0 for a
> > parport with disabled IRQ. // Thomas jdthood_AT_yahoo.co.uk
>
> IRQ 0 is a legal valid IRQ. I suspect the problem is that pnpbios shouldnt
> be reporting an IRQ or we should be using some kind of NO_IRQ cookie
>

IRQ 0 is hardwired to the system timer in PC systems, though, so it
could simply be assumed that IRQ 0 will never be used for any other
purposes.

Reminds me back in the days when you had to worry about DRQs as well;
DRQ 0 was hardwired in the original PC but then became available in
the AT; there was a whole bunch of things that assumed DRQ 0 wasn't
usable, even though it was perfectly fine. Not to mention the
motherboard I had which would lock up solid if anything ever used
DRQ 5.

Good riddance, all this crap...

-hpa
--
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