On Thu, Oct 6, 2011 at 3:03 PM, Nishanth Aravamudan <nacc@xxxxxxxxxx> wrote: > We have observed the following on Power systems with SR-IOV capable > adapters: > > lpfc 0002:01:00.0: device not available because of BAR 7 [0x000000-0x00ffff] collisions > > The issue is that on Power systems, PCI BARs cannot be remapped and VF > BARs might have values that collide. As far as I can tell, the current > SR-IOV code cannot be supported on Power and so it seems like we could > provide a hook for an architecture that might set CONFIG_PCI_IOV to > disable SR-IOV support (potentially at run-time). Are you saying that Power is intrinsically unable to support SR-IOV? Or is it merely that we can't use SR-IOV on this particular machine/configuration because the BAR assignments are fixed and there isn't enough space for the VF BARs? I would expect the latter, and therefore it seems wrong to disable it across the board. Perhaps on another machine with different PCI resource assignments, there *would* be space for the VF BARs and SR-IOV could be used. > I defined a weak version of this function that returns true if > CONFIG_PCI_IOV is set (which I think should reflect the current setup > that CONFIG_PCI_IOV represents an unconditional support of SR-IOV) and > false otherwise. The only architecture that implements the hook is > powerpc, which uses a machine callback to decide if a platform supports > SR-IOV or not. I only defined one such callback, for the pseries > platform, and return false unconditionally there. I think this approach is a band-aid that happens to cover up the problem. I'd rather fix the PF enable path so it doesn't depend on VF BAR allocation. That seems like a much cleaner approach to me. I think your pci_select_bars() patch is acceptable for now, even though I would still like to see us move all the VF BAR stuff out of the pci_dev and into the pci_sriov. It's true that this patch might be "safer" in the sense that it barely touches the generic code, but I'd prefer to take the risk and make the generic code better for everybody. Bjorn -- 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
