On Tuesday 04 February 2014 12:10:55 Jason Gunthorpe wrote: > > For instance to support peer-to-peer IO you need to have a consisent, > non-overlapping set of bus/device/function/tag to uniquely route TLPs > within the chip. Cross domain TLP routing in HW is non-trivial. Yes, that is a good reason. > IOMMUs (and SR-IOv) rely on the BDF to identify the originating device > for each TLP. Multiple domains means a much more complex IOMMU > environment. I fear we already have to support complex IOMMU setups on ARM, whether there are multiple PCI domains or not. But it would be nice in theory not to require it. > Failure to integrate on-chip devices into the PCI world also means > thing like SR-IOv won't work sanely with on-chip devices. I'd consider this a feature ;) But you are probably right: people will do SR-IOV whether we like it or not, and they will try to do it on non-PCI devices too, and great suffering will be involved. Arnd -- 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
