AUTOCONF(4) Device Drivers Manual (luna68k) AUTOCONF(4)

autoconfdiagnostics from the autoconfiguration code

When NetBSD bootstraps it probes the innards of the machine on which it is running and locates controllers, drives, and other devices, printing out what it finds on the console. This procedure is driven by a system configuration table which is processed by config(1) and compiled into each kernel.

Normally, the system uses the disk from which it was loaded as the root filesystem. If that is not possible, or if such a system is booted with the RB_ASKNAME option (see reboot(2)), then the name of the root device is read from the console terminal at boot time, and any available device may be used.

unknown CPU type
You tried to boot NetBSD on a CPU type which it doesn't (or at least this compiled version of NetBSD doesn't) understand.
%s%d at mainbus0
%s%d: %s
An on-board device controller was found.

config(1), hp300/intro(4)

June 12, 2022 NetBSD 10.99