On Fri, Nov 01, 2019 at 12:41:48PM +0100, Jean-Philippe Brucker wrote: [...]
> > > I'm also wondering about ACPI support. > > > > I'd love to add ACPI support too, but I have zero knowledge of ACPI. > > I'd be happy to help anyone who wants to add ACPI support that allows > > ACPI to add device links. > > It's not as generic as device-tree, each vendor has their own table to > describe the IOMMU topology. I don't see a nice way to transpose the > add_links() callback there. Links need to be created either in a common > path (iommu_probe_device()) or in the APCI IORT driver. We can create a generic stub that calls into respective firmware handling paths (eg iort_dma_setup() in acpi_dma_configure()). There are three arches booting with ACPI so stubbing it out in specific firmware handlers is not such a big deal, less generic sure, but not catastrophically bad. Obviously this works for IOMMU masters links - for resources dependencies (eg power domains) it deserves some thought, keeping in mind that IOMMUs are static table entries in ACPI and not device objects so they are not even capable of expressing eg power resources and suchlike. Long story short: adding IOMMU masters links in ACPI should be reasonably simple, everything else requires further thought. Lorenzo _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
