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:
- The stack pointer addresses for each privilege level.
- Pointer Addresses for the Interrupt Stack Table (The inner-level stack pointer section above, discusses the need for this).
- 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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