First, it's bad for security, secondly, in my setup, it fails to work --
modprobe -f vboxdrv
FATAL: Error inserting vboxdrv (/lib/modules/3.4.2-gentoo-r1/misc/vboxdrv.ko): Invalid module format
I guess it's cause MODULE_SRCVERSION_ALL is enabled.
Can you be a bit more precise please? What does run "modprobe -f vboxdrv" on your system?
A script called VBox_load_modules exists in app-emulation/virtualbox which loads all virtualbox modules.
By default this script uses the -f switch with modprobe to load modules, which does not work on my system.
I don't see that this file still exists on current in-tree virtualbox-versions. I've also done recursive greps for any modprobe calls in bundled scripts and I find no problems. Please re-open the bug if you find that there is still a problem somewhere.