[jbooth]

Yeah, it's stupid. I think the underlying rationale was that the arrays are indexed with ints, and that decision was made in 1995 with universally 32-bit machines.

You can hack around it by having multiple memory mappings over a file starting at different offsets, but just use C honestly if you're doing something that's math-heavy and needs really big memory-mapped files, C's better for both of those anyways.