I went all the way back to NetBSD 2 and was able to boot, just barely.
I can also boot SunOS 4.11 comfortably (no surprise).
When I try and boot 9.3, I don't successfully get through single-user
mode. I'm net-booting, and if I'm not mistaken, there is no remote
swap support in single-user mode, so I think I've hit a roadblock and
4M is just not sufficient to get the job done.
If its not fully wired in on the boot loader/ kernel side then that's "just a matter of code" :)
Are you able to boot single user, add swap and then hit ^D to continue multi user?
David