running freebsd completely from memory : possible?

[Sergio de Almeida Lenzi]

Sure!!!   peace of cake...  you can boot freebsd diskless, and run
entirely from memory with 128Mb of memory and i386 kernel, including
the new FreeBSD 12.
Or you can boot it from a memory stick, entirely on memory and run from
there 
Or you can boot from a CD, bring the system from the network and run
from there...

The same for NetBSD..  

It has been working since FreeBSD 1, I think...