>> Well, there is no "target kvm" but "target kcore" still exists.  But it
>> doesn't work - whether or not I supply a pathname, it complains
>
>> 	No kernel exec file specified
>
> Did you start gdb like this?
>
> gdb /path/to/netbsd

Yes:

quicky:paul {115} gdb netbsd.0.core
GNU gdb 5.3nb1
Copyright 2002 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
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There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "x86_64--netbsd"..."/home/paul/netbsd.0.core": not in executable format: 
File format not recognized

(gdb) target kcore
No kernel exec file specified
(gdb)

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