These interfaces return current information about the system, such as the root node of the system dev_info tree, and the values of certain system-wide parameters.
dev_info_t *ddi_root_node(void);ddi_root_node(9F) returns a pointer to the root node of the system dev_info tree. Device drivers rarely use this.
clock_t ddi_get_lbolt(void);ddi_get_lbolt(9F) returns the number of clock ticks since the last system reboot for use as a timer.
time_t ddi_get_time(void);ddi_get_time(9F) returns the current time in seconds since 00:00 UTC, January 1, 1970. This value can be used to set or wait for expiration intervals.
pid_t ddi_get_pid(void);ddi_get_pid(9F) returns the process id of the current process.