sysctl to prevent reboot?

Hi,

I am not sure where but I thought I saw a change fly by which would
prevent a shutdpwn -r /reboot (and possibly halt?) from being executed
while a sysctl was set.

Does anyone have a reference or have I been dreaming?

I would find that very helpful for host systems running (multiple) bhyve
instances.  Happened twice to me recently that I typed reboot in the wrong
window and restarted my dev machine entirely rather than a guest.

/bz

-- 
Bjoern A. Zeeb                                                     r15:7