On Thu, 2007-09-13 at 15:16 +0400, Ivan Kokshaysky wrote: > On Thu, Sep 13, 2007 at 02:53:13AM -0700, Greg KH wrote: > > On Thu, Sep 13, 2007 at 01:55:36AM -0600, Matthew Wilcox wrote: > > > Unfortunately if this patch does cause any machine to break, these will > > > be machines that worked fine up until this point, so that would be a > > > regression, which is worse. Life sucks. > > > > If, after a while, you think the change should go into the -stable tree, > > I have no objection. > > I think it shouldn't - this change will almost certainly cause a regression. > There is a lot of system devices besides the host bridges that shouldn't be > disabled during BAR probe, like interrupt controllers, power management > controllers and so on. > > We need a more sophisticated fix - I'm thinking of introducing "probe" field > in struct pci_dev which can be set by "early" quirk routines.
Agreed. I have a similar problem on ppc where it's common to have things like the main PIC on a PCI device. Note that another problem is (or at least was, i haven't checked recently) the P2P bridge scanning code that, in a similar way, can block the path to all devices below it. I -do- have a case for example with Apple Xserve G4's where the main Apple IO ASIC, which is a PCI device containing the PIC, the power management controller, and various low level system control IOs is behind a pair of P2P bridges. One solution for us (PPC) is to enforce those devices and bridges to be described in the OF tree, and generalize a bit the code we have for some 64 bits machines, that synthetizes the pci_dev's from the OF nodes rather than probing. But that's not going to help other archs. In fact, that's a problem we also have with pci_assign_unassigned_resources() which will happily move things around that must not be moved, especially when sitting behind P2P bridges. So the root of the issue is much deeper than just a quirk here I believe. Cheers, Ben. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/