Task State Segment - TSS in X86-64 Mode

TSS in X86-64 Mode

The x86-64 architecture does not support hardware task switches. However the TSS can still be used in a machine running in the 64 bit extended modes. In these modes the TSS is still useful as it stores:

  1. The stack pointer addresses for each privilege level.
  2. Pointer Addresses for the Interrupt Stack Table (The inner-level stack pointer section above, discusses the need for this).
  3. Offset Address of the IO permission bitmap.

Also, the task register is expanded in these modes to be able to hold a 64-bit base address.

Read more about this topic:  Task State Segment

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