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SubjectRe: [PATCH] x86 PCI detection and documentation
Hello!

> > Some years ago, the PCI routines have really used this strategy
> > (and the obsolete help text reflects this situation), but unfortunately,
> > there exist machines where the direct access detection gives bogus
> > results, so it's much better to ask the BIOS first. Also, it's conceptually
> > cleaner to use a well-defined BIOS interface than to probe random
> > ports (well, they are random on all non-PCI machines).
> >
> > These are the reasons why I'd prefer keeping the current code and
> > just fixing the documentation.
>
> AFAICS the current code does not follow this line of thought
> completely, as it still probes the hw directly after asking the
> BIOS, even though the BIOS might have returned valid data.
>
> So I propose the following patch (patch 1) that changes the code
> to check the BIOS results before probing directly and changes the
> documentation to reflect this.

It seems you've misunderstood the code (I agree it isn't as straightforward
as I would wish, but the whole PCI probing business is a bit fishy anyway).
The current probing code doesn't ignore the BIOS check results at all --
the check_pcibios() function looks which direct access methods are said by
the BIOS to be supported by the hardware and if there are any, we continue
with probing these direct access methods. Only if they fail or the BIOS reports
no known direct access methods, we fall back to using the BIOS functions.
(There is a couple of good reasons for trying to avoid using BIOS to access
the configuration registers -- these functions are slow and sometimes buggy.)

I still think the code is correct and only the documentation needs to be
updated (I'll send a patch to Linus as soon as I catch up with my mail queue).

> If this is rejected for some reason, I include a patch 2 that
> merely changes the Documentation/Configure.help to reflect how
> the code works currently.

Unfortunately, it doesn't :(

Anyway, have you already tried "pci=conf1" as I've suggested in my previous mail?

Have a nice fortnight
--
Martin `MJ' Mares <mj@ucw.cz> <mj@suse.cz> http://atrey.karlin.mff.cuni.cz/~mj/
"Linux vs. Windows is a no-WIN situation."
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