[apologies: sending again because linux-mm address was wrong] On 11/02/2016 21:18, Jason Gunthorpe wrote: > Resubmit those parts under the mm subsystem, or another more > appropriate place. We want the feedback from linux-mm, and they are now Cced. > If you want to make some incremental progress then implement the > existing ZONE_DEVICE API for the IB core and add the invalidate stuff > later, once you've negotiated a common API for that with linux-mm. So there are couple of issues we currently have with ZONE_DEVICE. Perhaps they can be solved and then we could use it directly. First, I'm not sure it is intended to be used for our purpose. memremap() has this comment [1]: > memremap() is "ioremap" for cases where it is known that the resource > being mapped does not have i/o side effects and the __iomem > annotation is not applicable. Does this apply also to devm_memremap_pages()? Because the HCA BAR clearly doesn't fall under this definition. Second, there's a requirement that ZONE_DEVICE ranges are aligned to section-boundary, right? We have devices that have 8MB or 32MB BARs, so they won't work with 128MB sections on x86_64. Third, I understand there was a desire to place ZONE_DEVICE page structs in the device itself. This can work for pmem, but obviously won't work for an I/O device BAR like an HCA. Regards, Haggai [1] http://lxr.free-electrons.com/source/kernel/memremap.c?v=4.4#L38 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>