On Saturday 10 January 2009, Jesse Barnes wrote: > On Thursday, January 8, 2009 12:45 pm Rafael J. Wysocki wrote: > > On Thursday 08 January 2009, Rafael J. Wysocki wrote: > > > On Thursday 08 January 2009, Kenji Kaneshige wrote: > > > > Rafael J. Wysocki wrote: > > > > > On Thursday 08 January 2009, Kenji Kaneshige wrote: > > > > >> Rafael J. Wysocki wrote: > > > > >>> From: Rafael J. Wysocki <rjw@xxxxxxx> > > > > >>> > > > > >>> If MSI-X interrupt mode is used by the PCI Express port driver, too > > > > >>> many vectors are allocated and it is not ensured that the right > > > > >>> vectors will be used for various services. Namely, the PCI Express > > > > >>> specification states that both PCI Express native PME and PCI > > > > >>> Express hotplug will always use the same MSI or MSI-X message for > > > > >>> signalling interrupts, which implies that the same vector will be > > > > >>> used by both of them. Also, the VC service does not use interrupts > > > > >>> at all. Moreover, is not clear which of the vectors allocated by > > > > >>> pci_enable_msix() will be used for PME and hotplug and which of > > > > >>> them will be used for AER if all of these services are configured. > > > > >>> > > > > >>> For these reasons, rework the allocation of interrupts for PCI > > > > >>> Express ports so that at most two vectors are allocated and ensure > > > > >>> that the right vector will be used for the right purpose. > > > > Appended is a cleaned-up version of the patch that also contains comments > > with references to the appropriate sections of the PCI Express spec. > > We'll need testing here in any case; I'll have to re-read the specs carefully > to see if we can really rely on the vector numbers you have here (at first > glance Kenji-san's approach seems more robust). It has a catch too. Namely, is there any warranty that we'll get the same vectors when the second pci_enable_msix() is called and that they will be in the same order? Rafael -- 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
