This function is invoked by the operating system whenever the CPU is idle (i.e., when no tasks are ready to execute). It provides a mechanism to switch the CPU into a power-saving mode, from which it must resume execution upon the next interrupt event.

This is typically implemented using architecture-specific instructions, such as HLT on i386 or HALT on Motorola 68k. If the target processor does not support a method for suspending CPU execution, the body of this function should remain empty.