Debugging the ZDB debugger.

[Zaphod Beeblebrox]

So ... I have several zfs filesystems with errors that may or may not be
real.  I've talked about this in the mailing lists before, and I was
endeavoring to chase this all down with zdb ... to see what was real.

zdb -dd vr2/tmp      <--- works

zdb -ddd vr2/tmp     <--- crashes

zdb -dddd vr2/tmp     <--- also crashes.

When I run "gdb -c zdb.core zdb" I get a whole bunch of:

[New Thread 803406c00 (LWP 101333/zdb)]
[New Thread 803406800 (LWP 101332/zdb)]
[New Thread 803406400 (LWP 100598/zdb)]

(probably 30 or so) and then:

(gdb) bt
#0  0x00000000004098a9 in ?? ()
#1  0x0000000000406222 in ?? ()
#2  0x000000000040528f in ?? ()
#3  0x0000000800632000 in ?? ()
#4  0x0000000000000000 in ?? ()

Seeing this, I went to the /usr/src/cddl/usr.sbin/zdb directory and tried
recompiling ... but it already puts -g in there --- so ...

What do I need to do to debug the debugger?