On Wednesday 14 January 2009, Kenji Kaneshige wrote: > 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? No, I don't. It was just confusion on my side, sorry. Please have a look at the new version of the patch I sent yesterday (http://marc.info/?l=linux-pci&m=123185510828181&w=4). Thanks, 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
