subsys_virtual_register — register a subsystem at /sys/devices/virtual/
|struct bus_type * subsys,|
|const struct attribute_group ** groups|
All 'virtual' subsystems have a /sys/devices/system/<name> root device with the name of the subystem. The root device can carry subsystem-wide attributes. All registered devices are below this single root device. There's no restriction on device naming. This is for kernel software constructs which need sysfs interface.