Re: PCI memory allocation bug with CONFIG_HIGHMEM

[Linus Torvalds]

On Tue, 6 Jan 2004, Andi Kleen wrote:
> 
> Anyways, I already implemented reservation for the aperture for the K8
> driver some time ago. And it's in your tree. But it doesn't help for 
> finding IO holes because there could be other unmarked hardware lurking
> there ... Or worse there is just no free space below 4GB.

The "unmarked hardware" is why we have PCI quirks. Look at 
drivers/pci/quirks.c, and notice how many of the quirks are all about 
quirk_io_region().  Exactly because there isn't any way for the BIOS to 
tell us about these things on the IO side.

(Actually, there is: PnP-BIOS calls are supposed to give us that
information. However, not only are the BIOSes buggy and don't give a
complete list _anyway_, anybody who uses the PnP-BIOS is much more likely
to just get a kernel oops when the BIOS is buggy and assumes that only
Windows will call it. So I strongly suggest you not _ever_ use pnp unless
you absolutely have to).

The same quirks could be done on the MMIO side for northbridges.

			Linus
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