On Mon, May 13, 2013 at 11:05:48AM +0200, Alexander Gordeev wrote: > Note, although the existing 'msi_desc::multiple' field might seem > redundant, in fact in does not. In general case the number of MSIs a > PCI device is initialized with is not necessarily the closest power- > of-two value of the number of MSIs the device will send. Thus, in > theory it would not be always possible to derive the former from the > latter and we need to keep them both, to stress this corner case. > Besides, since 'msi_desc::multiple' is a bitfield, throwing it out > would not save us any space. The last paragraph makes me curious. The only place where 'multiple' is set is in do_setup_msi_irqs() and this uses the next power of two for it. And since a device is not enabled twice, it is not overridden. So it should be possible to compute 'multiple' out of 'nvec' but it saves cycles not do to so. I agree to keep 'multiple' but your argument does not seem to make sense. While nitpicking, 'nvec' might deserve a better comment than 'number of messages' since it holds the number of allocated interrupts. :) Sebastian -- 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
