[openib-general] [discuss] Re: 2.6.19-rc4: known unfixed regressions (v3)

[ebiederm at xmission.com]

Linus Torvalds <torvalds at osdl.org> writes:

> On Wed, 8 Nov 2006, Matthew Wilcox wrote:
>>
>> On Wed, Nov 08, 2006 at 08:39:44AM +0100, Andi Kleen wrote:
>> > ACPI knows the number of busses.
>> 
>> But what if the number of busses increases later, eg by hotplugging
>> a card with a PCI-PCI bridge on it?  Or does it know the number of
>> busses which can be supported by this machine's MMCONFIG region?
>
> ACPI will give the maximum number.
>
> However, in this case, the correct thing to do (always _has_ been) is to 
> not use ACPI for _anything_, but just read the base and the size of the 
> MMCONFIG region from the hardware itself.
>
> Anyway, I do not consider this a regression. MMCONFIG has _never_ worked 
> reliably. It has always been a case of "we can make it work on some 
> machines by making it break on others".

The implementations I have seen, I believe have all been on bridges and
the maximum size is actually generated from the bus number below the bridge.

Eric