Re: [RFC PATCH 3/3] mm/map_contig: Add mmap(MAP_CONTIG) support

On Fri, 13 Oct 2017, Michal Hocko wrote:

quoted

There is a generic posix interface that could we used for a variety of
specific hardware dependent use cases.

Yes you wrote that already and my counter argument was that this generic
posix interface shouldn't bypass virtual memory abstraction.

It does do that? In what way?

quoted

There are numerous RDMA devices that would all need the mmap
implementation. And this covers only the needs of one subsystem. There are
other use cases.

That doesn't prevent providing a library function which could be reused
by all those drivers. Nothing really too much different from
remap_pfn_range.

And then in all the other use cases as well. It would be much easier if
mmap could give you the memory you need instead of havig numerous drivers
improvise on their own. This is in particular also useful
for numerous embedded use cases where you need contiguous memory.