loading vmm.ko crashes main-n267684-e4b646ce1610

Hello,

Loading vmm either via vmm_load=YES in /boot/loader.conf or
manually via kldload vmm crashes the system to db> prompt
as shown in the link below:

http://void.f-m.fm.user.fm/Screenshot_20240122_135539.png

Thing is, access is via a html5 console with no up/down scrolling
or buffer. Nothing can be entered into the db> prompt. There's plenty
more information when it crashes, but the output scrolls off the top.

The main-n267684 is running a modified GENERIC-NODEBUG
kernel and has debugging turned off in /etc/src.conf 
(it has WITHOUT_ASSERT_DEBUG= and WITHOUT_DEBUG_FILES= and 
WITH_MALLOC_PRODUCTION=)

Apart from turning these on again and rebuilding GENERIC, what other things
need to be set to get a usable coredump when this happens?

/var/crash has nothing in it.

thanks in advance for any assistance
--