)
Values Cloaking port-trapping passalong address is called with:
	EAX = CS:IP of faulting instruction (unless executing in protected-mode
		ring 3)
	SS:EBX -> caller register structure (see #02559)
		check EFLAGS V86-mode bit for type
	CX = first two bytes of I/O instruction which was trapped
	DX = port to which I/O is being performed
	CF clear
Return: CF clear if RM386 should perform I/O operation
	CF set if I/O should be skipped
Note:	RM386 skips the trapped I/O instruction, so the passalong handler
	  should not modify the client CS:EIP