On Thu, 9 Apr 2015, Marc Zyngier wrote: > On Thu, 9 Apr 2015 13:00:23 +0100 > Ingo Molnar <mingo@xxxxxxxxxx> wrote: > > > > Hm, so this appears to be the first time that 'irq == 0' assumptions > > are getting into the genirq core. Is NO_IRQ dead? I realize that the > > MSI code uses '!irq' as a flag, but still, quite a few architectures > > define NO_IRQ so it appears to matter to them. > > NO_IRQ strikes back, everybody takes cover! ;-) > > More seriously, this seems to be two schools of thoughts on that one. > The irqdomain subsystem seems to treat 'irq == 0' as the indication that > 'this is not a valid IRQ', and so does MSI (as you noticed). Given that > this code deals with MSI in conjunction with irqdomains, it felt > natural to adopt the same convention. > > Also, not all the architecture are defining NO_IRQ, and it only seems > to be used in code that is doesn't look portable across architectures. > Either these architecture don't care about MSI, or they are happy > enough to consider that virtual interrupt 0 is invalid in the MSI case. > > So I'm a bit lost on that one. I sincerely thought NO_IRQ was being > retired (https://lwn.net/Articles/470820/). Should we introduce a > NO_MSI_IRQ (set to zero) to take care of this case? Nah, that'd be overkill. irq 0 is invalid for MSI in any case so we really should stick with that convention. Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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