I’m currently playing with VMs on freeBSD, a few way exists, jails, bhyve, cbsd, and, of course, the good ol’ VirtualBox.

Lately, i had a weird behavior. VirtualBox vms just do not start anymore. You get the window, but it never boots. You stay in front of a black screen and nothing happens.

After spending some time digging the internet, it turns out that the vmm kernel module conflict with virtualbox.

To confirm it’s your case, you can stop your virtualbox vms, enter # kldunload vmm, then reboot your vm.

If it works, congrats, we found the root cause!

Don’t forget to remove the vmm_load="YES" line in /boot/loader.conf and vmm from the kld_list in /etc/rc.conf