load TSS selector in GS -> GPF

[Ash]

Hi,

is it normal that I get a GPF when I load a TSS selector into a normal (ds, gs...) segment register?

I thought it would be handy to have the GS segment register in my OS always point to the current TSS and not waste another entry in the GDT for this purpose.

TIA,
Ash

[japheth]

is it normal that I get a GPF when I load a TSS selector into a normal (ds, gs...) segment register?

Yes.

[Ash]

Yes.

Thank you, at least I now know that it's not a bug.  :wink

Ash

[Tedd]

The segment registers hold segment selectors, the TSS still requires a descriptor in the GDT.
You then set its selector in the task-register (with LTR) - which caches the address of the TSS using the descriptor.