Rafael J. Wysocki wrote: > On Tuesday 13 January 2009, Kenji Kaneshige wrote: >> Rafael J. Wysocki wrote: >>> 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? >>> >> In my understanding, the following description of Interrupt Message >> Number in the PCI Express spec explains this. >> >> "[...] For a given MSI-X implementation, the entry must remain constant. [...]" > > The entry - yes, but the associated interrupt vector as sent to the CPU? That > seems to be platform-dependent. > I'm sorry but I don't understand what the problem is. Do you mean pci_disable_msix() doesn't work on some platforms? Thanks, Kenji Kaneshige -- 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
