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BOTOKILLER



Joined: 07 Jan 2011
Posts: 154
Location: Ukraine
BOTOKILLER
Hi everyone!
Yeah, I figured out how paging interacts with segments - LDT Very Happy
Where can I find LDT tutorial???

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NSOS
Post 27 Jul 2011, 12:08
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DJ Mauretto



Joined: 14 Mar 2007
Posts: 464
Location: Rome,Italy
DJ Mauretto
Always Intel Manuals Wink

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Post 27 Jul 2011, 12:17
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BOTOKILLER



Joined: 07 Jan 2011
Posts: 154
Location: Ukraine
BOTOKILLER
Which one???
Post 27 Jul 2011, 12:25
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f2



Joined: 30 May 2010
Posts: 13
Location: France
f2
BOTOKILLER wrote:
Which one???

Intel Architecture Software Developer’s Manual Volume 3: System Programming Guide

Hope you will search by yourself next time...
Post 27 Jul 2011, 12:31
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edfed



Joined: 20 Feb 2006
Posts: 4240
Location: 2018
edfed
BOTOKILLER wrote:
Which one???

the fact that you ask it means you did not read any.

hurry up! download ALL the manuals, don't forget to rename the pdf files with the true title of the volume, because a number is not very easy to remember.

and read all the manuals. you are not forced to read everything, but at least, try to overview the main topics of the manuals, and you will have a lot less question to ask.
Post 27 Jul 2011, 13:02
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BOTOKILLER



Joined: 07 Jan 2011
Posts: 154
Location: Ukraine
BOTOKILLER
edfed wrote:
BOTOKILLER wrote:
Which one???

the fact that you ask it means you did not read any.

hurry up! download ALL the manuals, don't forget to rename the pdf files with the true title of the volume, because a number is not very easy to remember.

and read all the manuals. you are not forced to read everything, but at least, try to overview the main topics of the manuals, and you will have a lot less question to ask.

I read them, In fact they are opened in a few tabs of chrome which I never close...

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NSOS
Post 27 Jul 2011, 13:12
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BOTOKILLER



Joined: 07 Jan 2011
Posts: 154
Location: Ukraine
BOTOKILLER
I cant find where LDT entry format is mentioned...

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NSOS
Post 27 Jul 2011, 16:11
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f2



Joined: 30 May 2010
Posts: 13
Location: France
f2
it's probably wiritten somewhere in Intel manuals (but I don't know where, I'm not interested about implementing such obsolete things like LDTs).

I have searched the Internet and I found an interesting page about segmentation on x86:
http://book.opensourceproject.org.cn/kernel/kernel3rd/opensource/0596005652/understandlk-chp-2-sect-2.html
Post 27 Jul 2011, 17:02
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BOTOKILLER



Joined: 07 Jan 2011
Posts: 154
Location: Ukraine
BOTOKILLER
f2 wrote:
it's probably wiritten somewhere in Intel manuals (but I don't know where, I'm not interested about implementing such obsolete things like LDTs).

I have searched the Internet and I found an interesting page about segmentation on x86:
http://book.opensourceproject.org.cn/kernel/kernel3rd/opensource/0596005652/understandlk-chp-2-sect-2.html

but LDT must somehow point to Page tables...

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NSOS
Post 28 Jul 2011, 11:53
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qandrew



Joined: 21 Jan 2010
Posts: 3
qandrew
BOTOKILLER wrote:

but LDT must somehow point to Page tables...


The LDT isn't related to Paging!


Why? It just isn't. As Wikipedia mentions, "On x86 processors not having paging features, like the Intel 80286, the LDT is essential to implementing separate address spaces for multiple processes.".

You should choose what you want to use: it is either Paging or LDT. Not both at the same time.
Post 28 Jul 2011, 12:23
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BOTOKILLER



Joined: 07 Jan 2011
Posts: 154
Location: Ukraine
BOTOKILLER
Shocked Shocked Shocked Embarassed Then what do I put into CS, DS, SS, etc when paging enabled???

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NSOS
Post 28 Jul 2011, 12:37
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 17639
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revolution
LDT/GDT defines segments and thus affects CS, DS, etc.

Paging defines access to memory pages and is independent of segments. Most modern OSes effectively disable segmentation by defining all segments to be 4GB (or run in 64 bit mode where there are no segments of consequence (except that pesky GS thing)).
Post 28 Jul 2011, 12:44
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BOTOKILLER



Joined: 07 Jan 2011
Posts: 154
Location: Ukraine
BOTOKILLER
So, I just have to put all segments to point to whole address space???
That simple Smile Smile Smile
Thanks guys!!!


Last edited by BOTOKILLER on 28 Jul 2011, 13:01; edited 1 time in total
Post 28 Jul 2011, 12:59
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f2



Joined: 30 May 2010
Posts: 13
Location: France
f2
Hmm... Well.

I fully agree that you ask lot of questions about something you can't understand. But mostly, you can easily answer these questions:
- by reading carefully the Intel manuals,
- or by following all existing tutorials about OS development.
- and, of course, if you have a question, search on theOSDev Wiki, the FASM board, or on Google. Post here ONLY if you can't find an answer that question.
Post 28 Jul 2011, 13:00
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