NetBSD/atari and >16MB TT RAM

I just filed a PR:
https://gnats.netbsd.org/cgi-bin/query-pr-single.pl?number=56710

I'm unable to get NetBSD/atari to operate reliably with >16MB TT RAM,
across entirely different machines / configs.  (With 16MB TT RAM it
runs rock solid.)

Since I'm able to reliably reproduce the issue during installation it
should in theory be easily debuggable, though I haven't made any
attempts at debugging yet myself.

Unfortunately it looks like the latest releases of NetBSD are using
enough memory that >16MB TT RAM is becoming a necessity, so this will
be a significant blocker going forward.

I put out a tweet thread with a bit more detail on my experimentation:
https://twitter.com/nbtt030/status/1492206644297535492

Dave