How do you tell if gates reference descriptors in the GDT or LDT?

[jj1984]

I noticed that Intel, when describing its gate formats, doesn't tell you how to set the gate so that it references a descriptor in the global descriptor table or local descriptor table.

Segment selectors when loaded into segment registers have a one bit field that signifies whether the selector references the GDT or LDT.

But I don't see any such field in gates.

There are some fields in the gates that aren't explained (at least not yet in the text).

But other than that, I don't see any possibility for how to tell whether the gate references the GDT or LDT.

Any thoughts?

 

[Cromewell]

A bit in the selector tells you which table to use (TI=0 GDT, TI=1 LDT):

 

[jj1984]

A bit in the selector tells you which table to use (TI=0 GDT, TI=1 LDT):

Right, just like if the selector had been entered into a segment register.

Same thing.

Got it.