[Gentoo] How to load kernel modules for Virtualbox

When start virtualbox will meet following error.

WARNING: The VirtualBox kernel modules are not loaded.
         Please load all the needed kernel modules by:

           for m in vbox{drv,netadp,netflt}; do modprobe $m; done

         You will not be able to start VMs until this problem is fixed.

Edit /etc/conf.d/modules.

modules="vboxdrv vboxnetadp vboxnetflt"

Reference:

• VirtualBox