Re: [Patch v2] Make PCI extended config space (MMCONFIG) a driver opt-in

Robert Hancock
2007-12-27T18:15:40Z

Linus Torvalds wrote:
>
> On Thu, 27 Dec 2007, Jeff Garzik wrote:
>> 2) [non-minor] hmmmm.
>>
>> [jgarzik@core ~]$ lspci -n | wc -l
>> 23
>>
>> So I would have to perform 23 sysfs twiddles, before I could obtain a full and
>> unabridged 'lspci -vvvxxx'?
>
> Or you force it on with "pci=mmconfig" or something at boot-time.
>
> But yes. The *fact* is that MMCONFIG has not just been globally broken,
> but broken on a per-device basis. I don't know why (and quite frankly, I
> doubt anybody does), but the PCI device ID corruption happened only for a
> specific set of devices.
>
> Whether it was a timing issue with particular devices or whether it was a
> timing issue with some particular bridge (and could affect any devices
> behind that bridge), who knows... It almost certainly was brought on by a
> borderline (or broken) northbridge, but it apparently only affected
> specific devices - which makes me suspect that it wasn't *entirely* due to
> just the northbridge, and it was a combination of things.

Pointer to such a report? The only single-device problems I'm aware of
are with some devices within the K8 integrated northbridge, which we
already handle. Other than that, the only non-global problems I'm aware
of are devices behind host bridges which can't receive/handle MMCONFIG
requests, in which case the problem would be bus-wide.

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Robert Hancock Saskatoon, SK, Canada
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