Okay, I found out why systat segfaults, and (probably) why libkvm
apps like xosview don't work for me.

systat opens /dev/ksyms okay but gets a ENXIO error when attempting
to read from it.

But if I call systat like this it works normally:
systat -N /usr/obj/sys/arch/i386/compile/MYKERNEL/netbsd

The systat manpage says "/netbsd" is used by default, but every
kernel built by build.sh is gzipped and not named "netbsd" so
I'm not quite sure how this is supposed to work.

Is systat really depending on reading the kernel file from the
root directory, or is /dev/ksyms supposed to be supplying the
same information?

BTW I definitely have "pseudo-device ksyms" in my kernel config,
and even the GENERIC kernel behaves the same for me, even when
it's unzipped and named "/netbsd".

#ls -l /dev/ksyms
cr--r--r--  1 root  wheel  101, 0 Jul 30 18:23 /dev/ksyms

Any clues how I can get /dev/ksyms working normally?

Any other info I can supply that might help?