Segment Descriptor Types

Segment Descriptor Types

August 23, 2023

Code- and Data-Segment Descriptor Types #

段描述符(Segment Descriptor)中的S位置1，那么描述符所指的段就是代码段或数据段。Type Field的最高位（第二个双字的第11位）用于区分数据段和代码段。

数据段其余三个位的含义分别如下：

  1. accessed (A),
  2. write-enable (W),
  3. expansion-direction (E)

代码段其余三个位的含义如下：

  1. accessed (A),
  2. read enable (R),
  3. conforming (C)

System Descriptor Types #

S位置0，描述符就被称为系统段描述符。主要分两类：

  1. System-segment Descriptors
    • Local descriptor-table (LDT) segment descriptor
    • Task-state segment (TSS) descriptor
  2. Gate Descriptors
    • Call-gate descriptor
    • Interrupt-gate descriptor
    • Trap-gate descriptor
    • Task-gate descriptor.

From #

Intel 64 and IA-32 Architectures Software Developer’s Manual