_enable instructs the processor to set the interrupt flag. On x86 systems, this function generates the Set Interrupt Flag (sti) instruction. On an IPF system, this instruction generates a Set System Mask (ssm) instruction with an argument that sets the interrupt control flag.
This function is only available in kernel mode. If used in user mode, a Privileged Instruction exception is thrown.
On IPF platforms, this routine is only available as an intrinsic.