Hello, I am hoping folks on this list can provide some answers for my following query. Thanks. Kanoj PS: Pls cc me on responses, I am not subscribed to the list. --- On Fri, 8/13/10, Kanoj Sarcar <kanojsarcar@xxxxxxxxx> wrote: > From: Kanoj Sarcar <kanojsarcar@xxxxxxxxx> > Subject: Linux mask_msi_irq() question > To: mitch.a.williams@xxxxxxxxx, tom.l.nguyen@xxxxxxxxx, mingo@xxxxxxxxxx > Cc: kanojsarcar@xxxxxxxxx > Date: Friday, August 13, 2010, 12:30 AM > Hello, > > I have a question on msix vector masking, and was hoping > one of > you could answer, instead of posting this question on one > of the lists. > > mask_msi_irq() is doing a readback of the vector mask after > masking > an entry. I tried to dig up the history on this, and came > across > Mitch's patch from Mar 2007 against 2.6.21 where he > implemented the > readback/flush during enable/disable operations: > http://marc.info/?l=linux-kernel&m=117459742025894&w=2 > > In 2.6.30, I see that even mask/unmask is doing the flush > (arch/x86/kernel/apic/io_apic.c chip handlers use the > function). > > Now the question: is it truly guaranteed from PCI/PCIE > and/or > MSIX specs that the memory read/flush indeed will provide a > strong > interrupt reception barrier? Or is it that some specific > devices > end up providing this guarantee above and beyond PCI/MSIX > specs? > > Thank you for any responses. > > Kanoj > > > > > > > -- 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
