port-atari/56710: port-atari freeze with >16MB TT RAM, on multiple machines with different configurations

[dross%pobox.com@localhost]

>Number:         56710
>Category:       port-atari
>Synopsis:       port-atari freeze with >16MB TT RAM, on multiple machines with different configurations
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    port-atari-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Feb 13 20:35:00 +0000 2022
>Originator:     David Ross
>Release:        8.2
>Organization:
>Environment:
>Description:
I have now tested two different Atari TT030s with different memory boards and different network adapters (Riebl card vs. NetUSBee) and observe that when the TT has >16MB of TT RAM, installation freezes.  While I can technically get past this blocker, I have also found that in all cases, with >16MB of TT RAM, the Atari TT030 is unstable.

More specifically, I have a 16MB Atari-branded TT RAM board that lets me use my system reliably.  But I've now tried three different >16MB TT RAM boards (different brands) across two different TT030's (a very early model and a very late model), and I always experience instability with >16MB RAM, at least when using the ATARITT kernel.

FWIW, Izumi Tsutsui also has a TT030 and apparently is able to get stable operation with 32MB TT RAM.  I just can't explain that though, given that my experimentation indicates that any TT030 configuration with >16MB TT RAM is unreliable.

If anyone is capable of debugging this and needs particular hardware to test, I may be able to help with that.
>How-To-Repeat:
1.  Install 32MB of TT RAM or more in an Atari TT030, using a Storm TT or similar memory board.
2.  Boot the ATARITT kernel into sysinst and install via HTTP.
Observe the install hangs during download of modules.tgz.
On the same Atari with 16MB of TT RAM or less, observe that install succeeds.

I do most of my testing on NetBSD 8.2, but 9.2 is similarly incompatible with >16MB TT RAM.
>Fix: