my system has 16 GB RAM:
CPU: 8-Core Intel Core i7-2820QM (-MCP-) speed/min/max: 2292/800/2301 MHz OS: FreeBSD 12.2-RELEASE-p3 amd64 Up: 3m
Mem: 3541.6/16222.2 MB (21.8) Storage: 3.81 TiB (87.9% used) Procs: 93 Shell: Zsh inxi: 3.1.07
Before the test about 12 GB RAM was free.
After I executed these I got instant panic/restart of the system.
# mdconfig -a -t malloc -s 8G -u 10
# geli onetime -s 4096 /dev/md10
# dd bs=1m if=/dev/zero of=/dev/md10.eli status=progress
Hope that helps.
What was the panic?
(In reply to Mark Johnston from comment #1)
System rebooted instantly without any info on the screen.
Like you would press the 'reset' button.