Re: [PATCH v2 00/19] mm: Support huge pfnmaps

[Ankit Agrawal]

> More architectures / More page sizes
> ------------------------------------
> 
> Currently only x86_64 (2M+1G) and arm64 (2M) are supported.  There seems to
> have plan to support arm64 1G later on top of this series [2].
> 
> Any arch will need to first support THP / THP_1G, then provide a special
> bit in pmds/puds to support huge pfnmaps.

Just to confirm, would this also not support 512M for 64K pages on aarch64
with special PMD? Or am I missing something?

> remap_pfn_range() support
> -------------------------
> 
> Currently, remap_pfn_range() still only maps PTEs.  With the new option,
> remap_pfn_range() can logically start to inject either PMDs or PUDs when
> the alignment requirements match on the VAs.
>
> When the support is there, it should be able to silently benefit all
> drivers that is using remap_pfn_range() in its mmap() handler on better TLB
> hit rate and overall faster MMIO accesses similar to processor on hugepages.

Does Peter or other folks know of an ongoing effort/patches to extend
remap_pfn_range() to use this?