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.
returns a pointer to the root node of the system dev_info
tree. Device drivers rarely use this.
returns the number of clock ticks since the last system reboot for use as a timer.
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.
returns the process id of the current process.