Re: BUG #17448: In Windows 10, version 1703 and later, huge_pages doesn't work.

On Sun, Mar 27, 2022 at 12:07:57AM +1300, Thomas Munro wrote:
> Some question I have: is FILE_MAP_LARGE PAGES a macro?  We claim to
> support all those ancient zombie OSes like Windows 7, or maybe it's
> even XP for 11, and this has to be back-patched to 11, so we might
> need to make it conditional.  But conditional on what?  For example,
> does something like the attached work (untested)?  What happens if a <
> 1703 kernel sees this flag, does it reject it or ignore it?

I have been looking at this thread, and found an answer in an example
of application creating a map object with large pages in [1]:
"This flag is ignored on OS versions before Windows 10, version 1703."

So based on that I think that we could just apply and backpatch what
you have here.  This issue is much easier to reason about on HEAD
where we just care about Win >= 10, and we've be rather careful with
changes like that when it came to Windows.  Any objections about doing
a backpatch?  I'd like to do so after an extra lookup, if there are no
objections.  Or would folks prefer a HEAD-only fix for now?

[1]:
https://docs.microsoft.com/en-us/windows/win32/memory/creating-a-file-mapping-using-large-pages?source=recommendations
--
Michael