Some boards which contain physically hot-pluggable PCIe slots such as 8639 connectors can hot-add devices simply by connecting them while up and writing to /sys/bus/pci/rescan. This probes the device and loads a driver. However when a device is added in this way it is not given an interrupt. Irqs seem to be passed by the PCI BIOS, or emulated PCI BIOS in the case of non x86 arches and so these hot-added cards naturally do not get one. This means that when a device is added in this way, unless the device and driver use only MSI/MSI-X it will try to request irq vector 0 which does not end well. To prevent this I have added a check for an empty irq vector and use pdev_fixup_irq to set one at run time if one has not been provided. This is done inside an unlikely block in order to make negligible the performance impact on the normal PCI device adding code path, this should not be a performance critical area anyway as devices are not often added. I have looked into instead modifying the rescan code however this would be a less effective solution as there is no convenient way there to run code between device probing and the driver loading and so would need a significant redesign. If anyone has any suggestions or feedback on this patch, or a better way to solve this issue should there be one, I would be very grateful. In addition I have only had the opportunity to test this code on non x86 platforms so if anyone has a x86 or AMD64 PC with physical hot-add capability I would be very appreciative if you could try running this. Best regards, Matthew drivers/pci/bus.c | 11 +++++++++++ drivers/pci/setup-irq.c | 2 +- include/linux/pci.h | 2 ++ 3 files changed, 14 insertions(+), 1 deletion(-) -- ------------------------------ For additional information including the registered office and the treatment of Xyratex confidential information please visit www.xyratex.com ------------------------------ -- 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
