The protection hardware of the 80386 is an integral part of the memory management hardware.
Protection applies both to segment translation and to page translation.
Each reference to memory is checked by the hardware to verify that it satisfies the protection criteria. Since the checks are performed concurrently with address formation, there is no performance penalty. Invalid attempts to access memory result in an exception. Refer to Chapter 9 for an explanation of the exception mechanism . The present chapter defines the protection violations that lead to exceptions.