LDT... What and Why?

[DarkTama]

I was just wondering how exactly you use an LDT.
I know that you define it the same way as a GDT.
Use LLDT to load it. But how do we access the
entries in it?

With a GDT we use something like
mov ax,SELECTOR_EQUATE
mov segmentregister,ax

But how do I do it with an LDT?

[Philippo]

>With a GDT we use something like
>mov ax,SELECTOR_EQUATE
>mov segmentregister,ax
>
>But how do I do it with an LDT?

just the same way, but the selector must have bit 2 set to 1.

this is the description of segment selectors:
bit 0-1 requested previlege level
bit 2 table indicator (0=gdt, 1=ldt)
bit 3-15 index into descriptor table

e.g.
0000000000001000b (=0x08) second gdt entry
0000000000001100b (=0x0C) second ldt entry

hope this helps

bye

Philippo