Specify if the vdev is a safety variant, and if so the safety variant version
#include <qvm/vdev-core.h>
enum { VDEV_SAFETY_NO = 0x55555555, VDEV_SAFETY_YES = 0xaaaaaaaa, VDEV_SAFETY_SELECTED = VDEV_SAFETY_NO };
If you are building a vdev for a system that will be safety-certified, set WANT_SAFETY, and specify the vdev version number.