I have an application running on OBSD 3.5 on an i386 machine with 4GB. It's very
memory-hungry (builds a big cache of retrieved on-disk data) and would happily
use all available memory (which I'd like) - unfortunately, it is limited by
RLIMIT_DATA to 1048576 KB (it allocates memory from the heap).

I am investigating using an mmap'd file for the buffer, but would also like to
understand if I can increase the hard limit of RLIMIT_DATA. Is this being set by
the MAXDSIZ kernel parameter? Can I "just" raise that number in vmparam.h and
recompile, or are there some fundamental limits based on structure sizes?

Thanks.