OSDev.org

Posted: **Tue Sep 04, 2007 4:30 am**

Hi
I am trying to write an OS that runs in IA-32e mode i have read the intel documantation on this

at curent my code is in protected mode
it has
gdt , idt , irqs, a keboard layout , and i can print mesages to the screan

it then tries to enable pagging and long mode(it makes seans to put them together becouse u change pagging setting to enable long mode)

paging is not enabled
i am using the NASM assembler
could some one pleas tell me how to

2. Enable physical-address extensions (PAE) by setting CR4.PAE = 1.

and

4. Enable IA-32e mode by setting IA32_EFER.LME = 1.

PS i have figured out how to do the other steps

Posted: **Tue Sep 04, 2007 4:45 am**

use this example, you'll save yourself lots of time
http://flatassembler.net/examples/longmode.zip

there was corresponding thread about these examples here http://board.flatassembler.net/forum.php?f=11

fasm is similar to nasm i think.

Posted: **Tue Sep 04, 2007 4:51 am**

AT&T assembler:

HJED wrote:2. Enable physical-address extensions (PAE) by setting CR4.PAE = 1.

Code: Select all

/* Set cr4.PAE */
mov %cr4, %eax
or $0x20, %eax
mov %eax, %cr4

4. Enable IA-32e mode by setting IA32_EFER.LME = 1.

Code: Select all

/* Set EFER.LME */
mov $0xC0000080, %ecx
rdmsr
or $0x100, %eax
wrmsr

Posted: **Tue Sep 04, 2007 6:01 pm**

Thank you

i foud i site that explanes chaging AT&T asm in to intel asm and now it works thanks
for your code it was realy help full

here is my code for swiching to long mode for others who have a smilar problem
c++

Code: Select all

 
long_mode1(); // start long mode int
    write_cr3((unsigned long *)0x9C000); // put that page directory address into CR3
    long_mode2(); // pagging int 2
    write_cr0( (unsigned long *)((unsigned long) read_cr0() | (unsigned long) 0x80000000)); // set the paging bit in CR0 to 1

NASM

Code: Select all

[global _read_cr0]
_read_cr0:
	mov eax, cr0
	retn

[global _write_cr0]
_write_cr0:
	push ebp
	mov ebp, esp
	mov eax, [ebp+8]
	mov cr0,  eax
	pop ebp
	retn

[global _read_cr3]
_read_cr3:
	mov eax, cr3
	retn

[global _write_cr3]
_write_cr3:
	push ebp
	mov ebp, esp
	mov eax, [ebp+8]
	mov cr3, eax
	pop ebp
	retn
[global _long_mode1]
_long_mode1:
  ; cr0.PG is alread at 0 

  ; Set cr4.PAE 
mov eax , cr4
or eax , 0x2000000
mov cr4 , eax  
  ; L4PT loaded in pagging.cpp
  retn
[global _long_mode2]
_long_mode2:
  
;Set EFER.LME
mov  ecx , 0xC0000080
rdmsr
or  eax , 0x100
wrmsr 
  rent
  ;rest in paging

once again thanks for your help

Posted: **Wed Sep 05, 2007 8:05 am**

HJED wrote:
Code: Select all
  rent

Typo?

Posted: **Wed Sep 05, 2007 3:43 pm**

Combuster wrote:
HJED wrote:
Code: Select all
  rent
Typo?

no it was in a pagging tutorial which had lot of erros

Posted: **Thu Sep 06, 2007 12:01 am**

HJED wrote:
Combuster wrote:Typo?
no it was in a pagging tutorial which had lot of erros

Well, it makes me wonder why you post code of which you know is incorrect.

Posted: **Thu Sep 06, 2007 1:55 am**

u assume i already new that orginaly i only found out it had lots of errors after i posted this

Posted: **Thu Sep 06, 2007 7:07 am**

still you should make an effort to check for errors before posting, both gramma and programing.

I usually write a post and then hit the "submit" button forgetting to read it through first.
and then i use alot of time editing the post. well maybe not alot of time, but anyways.

Code: Select all

10 GOTO 30
20 CORRECT ERROR
30 LOOK FOR ERROR!
40 IF ERROR FOUND GOTO 20
50 HIT SUBMIT

I never did learn basic but you get the message...

THIS POST BEEN EDITED "1" TIME!

Posted: **Thu Sep 06, 2007 4:44 pm**

what you just said dose`nt make sense the paging post wasn`t working i was going thought issue 1 @ a time the paging code dose now work and i din`t know that rent thing was an error until someone in this post told me because asm did`nt complain abut it

Posted: **Sun Sep 09, 2007 10:40 pm**

Paying rent will keep you from getting booted.

Posted: **Mon Sep 10, 2007 2:18 am**

whattttttt?

Posted: **Mon Sep 10, 2007 10:37 am**

paying rent will keep you from getting booted, but you could allso not pay rent and uffer the consequeses (damn i cant spell)

e.g. paying the rent is a smart thing to do.

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IA-32e mode

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