Kernel mode address mapping ckseg0 space ckseg1 space ckseg3 space cksseg space kseg0 space kseg1 space kseg3 space ksseg space kuseg space operations xkphys space xkseg space xksseg space xkuseg space kseg0 space kseg1 space kseg3 space ksseg space KSU, field [1] [2] kuseg space KX, bit