Messages in this thread | | | From | Arnd Bergmann <> | Subject | Re: [PATCH] arm64: Add architecture support for PCI | Date | Tue, 04 Feb 2014 20:21:38 +0100 |
| |
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
| |