LinuxQuestions.org - problems with linking objects -- must know some nasm\ASM\linker

Hello

I present 2 problem cases ,each case is followed with tested code
thankyou for any help

--paul--
.................................................................................................... ...........................
CASE 1--

case 1 will compile but segfault when I insert into kernel using insmod

paul@box:~$ nasm -f elf foo.asm -o a.o
paul@box:~$ gcc -c foo.c -o b.o
paul@box:~$ ld -r a.o b.o -o kernelmod.o
paul@box:~$ sudo insmod -f kernelmod.o
Password:
Warning: kernel-module version mismatch
kernelmod.o was compiled for kernel version 2.4.20
while this kernel is version 2.4.20-xfs
Warning: loading kernelmod.o will taint the kernel: no license
See [xxx] for information about tainted modules
Warning: loading kernelmod.o will taint the kernel: forced load
Segmentation fault

gee, other than version mismatch I dont get why this code fails,
it should play some cool tones on my pc speaker

Code:

 



---------------------code for case1---------------



====== c code which calls asm module =========



#define MODULE

#define __KERNEL__

#include  <linux/module.h>

#include  <linux/kernel.h>



















int init_module(void)

{



jump();



}

  void cleanup_module(void)

{









}



========== asm module ===========



 BITS 32



          GLOBAL jump









          SECTION .text



jump:



jmp Play















                          ;status in dx ,1= on 0 = off

ChangeSpeaker:

in al,0x61

cmp dx,1

jne off

or al,3

jmp on



off:

mov dx,3

not dx

and ax,dx

on:

out 0x61,al

RET

;end ChangeSpeaker







Sound:



;hertz in di

mov  dx,1                        ;turn on speaker

call ChangeSpeaker



mov al,0xb6

out 0x43, al



                                ;  calculate tone

        mov    dx,14h

        mov    ax,4F38h          ;  divisor of frequency

        div    di

                                ;  play tone

        out    42h,al            ;  lower byte of frequency

        mov    al,ah            ;

        out    42h,al            ;  higher byte of frequency



RET

;end sound





Delay:

        mov cx, 0xffff

        delay3:

        mov bx, 0xfff

        delay4:

        dec bx

        jnz delay4

        dec cx

        jnz delay3

RET

;end Delay









Play:



        pusha                    ;save regs

        lea si, [TONE_TABLE]    ;load sound data

GET_NEXT:

        mov di,[si]              ;grab a tone

        call Sound              ;play it

        call Delay







        add si,2

        cmp word [si],0

        jne GET_NEXT



        mov  dx,0                        ;turn off speaker

        call ChangeSpeaker











        ;restore regs and return

        popa

RET

;end Play







          SECTION .data



TONE_TABLE    dw 16,32,65,130,261,523,1046,0

CASE 2--
these 2 modules will not compile, they follow the same 'call external asm routine'
format except this should be compiled to ELF EXECUTABLE format ,ie it's NOT
a loadable module

paul@box:~$ nasm -f elf test.asm
paul@box:~$ gcc -O3 test.c test.o -o TEST
In file included from /usr/include/linux/sched.h:14,
from /usr/include/linux/mm.h:4,
from test.c:1:
/usr/include/linux/timex.h:173: field `time' has incomplete type
In file included from /usr/include/asm/smp.h:15,
from /usr/include/linux/smp.h:14,
from /usr/include/linux/sched.h:23,
from /usr/include/linux/mm.h:4,
from test.c:1:
/usr/include/asm/fixmap.h:80: parse error before "pgprot_t"
In file included from /usr/include/asm/smp.h:21,
from /usr/include/linux/smp.h:14,
from /usr/include/linux/sched.h:23,
from /usr/include/linux/mm.h:4,
from test.c:1:
/usr/include/asm/apic.h:85: parse error before "unsigned"
In file included from /usr/include/linux/sched.h:23,
from /usr/include/linux/mm.h:4,
from test.c:1:
/usr/include/linux/smp.h:29: parse error before '(' token

as you can see ,problems with headers.
I need __get_free_pages() ,which is defined in linux/mm.h
Are there really typos in these headers or is it the oder in
which they are included???
I have found that sometimes order matters if header.h is dependant on variables declared in another header, the latter must precede the former

[CODE

--------------------- code case 2---------------------------------

===== c module ============

#include <linux/mm.h>

int * kep;

void y()
{

// ring0 code to jmp to
asm volatile ("mov $0x666,%di; in $0x61,%al" );
asm volatile ("or $3,%al;out %al,$0x61" );
asm volatile ("mov $0xb6,%al;out %al,$0x43");
asm volatile ("mov $0x14,%dx; mov $0x4F38,%ax");
asm volatile ("div %di; out %al,$0x42");
asm volatile ("mov %ah,%al; out %al,$0x42 ");
}

main()
{
kep = __get_free_pages(0x40, 3);
JUMP();

}

================== asm module ====================

; test source file for assembling to ELF
; build with:
; nasm -f elf elftest.asm
; gcc -o elftest elftest.c elftest.o
; (assuming your gcc is ELF)

; This file should test the following:

BITS 32

GLOBAL JUMP
EXTERN kep
EXTERN y

SECTION .text

JUMP:
mov dword esi,[kep]
lea edi,[y]
mov byte [esi],0xea
mov dword [esi+1],edi
jmp dword [kep]

SECTION .data

[/CODE]