Also noted, I just hit this issue building a custom kernel.
You should be using /sys/bus/usb/drivers now when mounting usbfs so stuff like VirtualBox and VMWare will work.
none /sys/bus/usb/drivers usbfs devgid=XXX,devmode=664 0 0
CONFIG_USB_DEVICEFS affects using usbfs, at all hence not enabling this will not allow you to use usbfs.
Also noted, I just hit this issue building a custom kernel.
You should be using /sys/bus/ usb/drivers now when mounting usbfs so stuff like VirtualBox and VMWare will work.
none /sys/bus/ usb/drivers usbfs devgid= XXX,devmode= 664 0 0
CONFIG_USB_DEVICEFS affects using usbfs, at all hence not enabling this will not allow you to use usbfs.