(In case this topic is still relevant) On Thu, May 09, 2013 at 06:09:42PM +1000, Benjamin Herrenschmidt wrote: > Do we provide drivers any guarantee to what happen if an MSI is shot > while masked with disable_irq() or while not yet request_irq()'ed ? > > Do we guarantee delivery (latched while masked), non-delivery, or > undefined ? I am not aware of any guarantees the kernel gives in this situation. I think it would just drop the IRQ and print a "nobody cared" message. > I'm bringing up a piece of HW where if it happened, it won't be > automatically sent to the CPU and can block further MSIs unless I > explicitly either ditch it or force a resend when unmasking (at the PCI > Express controller PIC level). > > I'm tempted to just ditch anything that happened while masked, it would > make everything easier on my side, but maybe drivers have different > expectations (and of course an LSI would still shoot, that's not an > issue, only MSIs are in question here). > > I have cases of devices continuing to shoot one or two MSIs after kexec > and before the new kernel takes over, causing a "loss" of any subsequent > one unless I deal with that case one way or another. I would also just ditch such IRQs that happen in that kexec case and make sure that they will work again when the kexec-kernel device driver wants to initialize them. Joerg -- 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
