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IDT, GDT, LDT and other about the memory
Posted: Sat Nov 09, 2002 8:43 am
by Unexpected
Hi,
Can anyone help or give me a link about IDT, GDT, LDT and other....
I wan't understand whats that and how it works...
And how use this...
Please help.. Thanx you!
Re:IDT, GDT, LDT and other about the memory
Posted: Sat Nov 09, 2002 12:50 pm
by Elfredo
Hi,
there is a tutorial along with some source code about Protected Mode on this site. But for an in-depth explanation i would recommend the intel docs (especially intel 386 programmers reference volume 3), also avaible on the site.
http://my.execpc.com/CE/AC/geezer/os/
Re:IDT, GDT, LDT and other about the memory
Posted: Sat Nov 09, 2002 6:58 pm
by K.J.
From
http://osdev.neopages.net/tutorials/gettingstarted.php:
Q: What is a GDT?
A: A gdt is a table containing selectors. Basically it provides a starting address to address all selectors.
Q: What is a selector?
A: A selector(sometimes also called a descriptor) is a definition of a segment. It contains a description of basic segment attributes, like the segment base (it's starting address) and the segments limit (it's length). Each selector is 64 bits long. More about them in the description of a GDT and LDT.
K.J.
Re:IDT, GDT, LDT and other about the memory
Posted: Sat Jan 04, 2003 8:57 pm
by Perica
..
Re:IDT, GDT, LDT and other about the memory
Posted: Sat Jan 04, 2003 9:13 pm
by jrfritz
Local Descriptor Table.
It's for hardware multitasking...right?
Re:IDT, GDT, LDT and other about the memory
Posted: Sun Jan 05, 2003 12:41 am
by K.J.
It's for hardware multitasking...right?
No, the LDT is so each process/thread can have it's own 'mini' GDT' sorta. It works with software or hardware multitasking.
K.J.
Re:IDT, GDT, LDT and other about the memory
Posted: Sun Jan 05, 2003 6:14 am
by Pype.Clicker
Tom wrote:
It's for hardware multitasking...right?
somehow, it is ... As each TSS can be given a personnal LDT, you can enforce more protection within the same address space if you give separated TSS separated LDTs. You can even use it in a software or hybrid multitasking if you have used segments or call/task gates somewhere and don't want every process to get the same priviledge access ...