Protection

The 80386 processor implements five different types of protection for tasks executing within the system. These are:

  • Type checking

  • Limit checking

  • Privilege levels

  • Restriction of procedure entry points

  • Restriction of instruction set.

    Each instruction and memory reference is checked by the hardware to ensure compliance with the protection rules prior to execution. For memory references, checking is performed during the address translation process, and is applied to both segmented and paged memory models. Protection parameters are stored in the segment descriptors or in the Page Directory and Page Table entries.

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