On 18.09.21 07:18, Christoph Hellwig wrote:
On Sat, Sep 18, 2021 at 12:22:47AM +0300, Mike Rapoport wrote:
I did some digging and it seems that the most "generic" way to check if a
page is in RAM is page_is_ram(). It's not 100% bullet proof as it'll give
false negatives for architectures that do not register "System RAM", but
those are not using dma_map_resource() anyway and, apparently, never would.
The downside of page_is_ram is that it looks really expensiv for
something done at dma mapping time.
There would be ways to speed it up, similar to
https://lkml.kernel.org/r/20210902160919.25683-2-david@xxxxxxxxxx
but the end result is still walking a list. Question would be, how much
that overhead matters in practice.
--
Thanks,
David / dhildenb
