On Mon, Apr 27, 2015 at 02:08:10PM +0100, Varun Sethi wrote: > > >>> In the SMMU/GIC-500-ITS world the iommu isolation ID (the stream ID) > > >>> and the GIC-ITS device ID are in fact the same ID. > > >> > > >> The DeviceID is the "MSI group" you mention. This is what provides > > >> isolation at the ITS level. > > >> > > > [varun] True, in case of a transparent host bridge device Id won't > > > provide the necessary isolation. > > > > Well, it depends how you look at it. How necessary is this isolation, since > > we've already established that you couldn't distinguish between these > > devices at the IOMMU level? > > > [varun] Yes, the devices would fall in the same IOMMU group. So, devices > would end up sharing the interrupt? Well, I think that's the crux of the issue here. If IOMMU groups are also needed to relay constraints to the IRQ subsystem, then perhaps we need a more general notion of device grouping and ID transformations between the different levels of group hierarchy. Will -- 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
