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
