On Tue, 2009-06-16 at 16:05 -0700, Linus Torvalds wrote: > > On Tue, 16 Jun 2009, Andrew Patterson wrote: > > > > That is at least one problem. I initially tried reparenting this stuff. > > That is what got backed out in > > http://thread.gmane.org/gmane.linux.kernel/768526/ > > Well, aren't we in the exact same situation still? Ie the problem (as > Matthew claims) is: > > 'Basically it was that we came across a machine with the opposite > problem -- that we found a parent after we found a child (and claimed > the child's resources), and had no way to insert the parent's region > above the child's region. Alex's machine finds the child after the > parent and needs to insert the child's resource inside the parent's > resource.' > > and the problem is that anything that isn't explicitly aware of the > topology is always going to be potentially confused about things like > this, since it's not clear at which level you want to find or add a > resource. > > > > But you fix it by making find_resource always go as deep as it can (if I > > > read the code correctly). > > > > Well, just deep enough. > > Ok, color me confused now. When is "as deep as it can" different from your > "just deep enough"? Maybe confusion on what is meant by 'as deep as'. My patch continues until it doesn't find a conflict including checking sub-children and stops as soon as an appropriate resource is found that does not conflict. Perhaps we mean the same thing. > > > Is there a reason that find_resources should stop at the roots immediate > > child/sibling. It seems like a bug to me. Hence this patch. > > Well, find_resource() found room for a resource. So it returns it. The > point is, your patch returns another - equally valid one. I am confused. The existing code will return a conflict and bomb out. > > Now, I'm not saying that your patch is wrong, but I _am_ worried that it > (once more) changes some random heuristic when we have two choices, and it > just makes it choose the other choice. Agreed. > > We've had those kinds of situations before. The thread you point to is an > exact case of this. My point is that I'd rather try to _avoid_ any > ambiguous cases, and try to solve it properly at a higher PCI level, where > the ambiguity doesn't exist any more (because we'd explicitly take the > actual bus topology into account). > So your patch may fix a bug, but I'm pretty sure I've seen a patch from > Ivan that should _also_ fix it, and that I would expect to do it not by > just tweaking a fundamentally ambiguous case. > OK. I would be happy to test Ivan's patch. > Linus > -- Andrew Patterson Hewlett-Packard -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
