[bogomipz]

Can someone say why is using the TSS still mandatory with software-based task switching? Is this a requirement imposed by x86?

In looking at the OS dev wiki I see the following:

>"The TSS is primarily suited for hardware multitasking, where each individual process has its own TSS. In Software multitasking, one or two TSS's are also generally used, as they allow for entering Ring 0 code after an interrupt."

Would you not be able to enter Ring0 after an interrupt with a TSS entry? Is this why it is still required?

[monocasa]

The interrupt stack pointer comes from the TSS. Without that you're still running on the untrusted user stack with no way of bootstrapping a kernel context without corrupting the user state.

[bogomipz]

Oh right, without a mapping its a "chicken and egg" situation. Cheers.