linux/module.h does not exist

tkmsr · 08-23-2010, 09:09 PM

I am not too sure as what is the problem as in the link to the book I gave the author does not even says to use the -I flag and the kernel series is for newbies only.I have checked the program twice

Code:

#include <linux/kernel.h>
#include <linux/module.h>
#include <sys/syscall.h>
extern void *sys_table[];
asmlinkage int(*main_sys_exit)(int);
asmlinkage int alt_exit_function(int err_code)
{
        printk("Sys_exit called with err_code=%d\n",err_code);
        return main_sys_exit(err_code);
}

int init_module()
{
        main_sys_exit=sys_table[__NR_exit];
        sys_table[__NR_exit]=alt_exit_function;
}
void cleanup_module()
{
        sys_table[__NR_exit]=main_sys_exit;
}

The way in the original book it says to compile is

Code:

gcc  -Wall -DMODULE -D__KERNEL__ -DLINUX -c sample2.c

The above is the way book says to compile it.
Just try once if you can get it working.
Check this link
http://www.spinics.net/lists/newbies/msg39939.html

Sergei Steshenko · 08-23-2010, 09:24 PM

Quote:

Originally Posted by tkmsr

...
The above is the way book says to compile it.
...

And why should anybody care about the book ?

You should be able to live by the standard and by the reality. In your reality the code shouldn't compile exactly because of the standard.

tkmsr · 08-24-2010, 12:23 AM

You are right to an extent.Given the fact that I am learning about Kernel Development what ever that book had said so I want to follow what ever is mentioned in that book.
Hence I have not yet left the program as the book says.
I did a find for the program as given in book

Code:

/usr/src/linux-headers-2.6.28-11-generic/include/linux/module.h
/usr/src/linux-headers-2.6.28-11-generic/include/linux/kernel.h
/usr/include/sys/syscall.h

Above are the files I feel the program is referring to.

So I executed

Code:

gcc -I /usr/src/linux-headers-`uname -r`/include  -I /usr/include -Wall -DMODULE -D__KERNEL__ -DLINUX -c sample2.c

but there were errors
you can see them here.
http://pastebin.com/hrYdjmZ4

I am giving up finally.
Thanks for staying here.

Sergei Steshenko · 08-24-2010, 07:32 AM

Quote:

Originally Posted by tkmsr

...
but there were errors
you can see them here.
http://pastebin.com/hrYdjmZ4

I am giving up finally.
Thanks for staying here.

The

Code:

/usr/src/linux-headers-2.6.28-11-generic/include/linux/linkage.h:5:25: error: asm/linkage.h: No such file or directory

error can be resolved the same way as previous errors. So, I do not understand why you are giving up.

tkmsr · 08-24-2010, 11:07 AM

Ok here is what made it work.
This is the program

Code:

#include <linux/kernel.h>
#include <asm/syscall.h>
#include <linux/module.h>
#include <linux/unistd.h>
extern void *sys_table[];
asmlinkage int(*main_sys_exit)(int);
asmlinkage int alt_exit_function(int err_code)
{
       printk("Sys_exit called with err_code=%d\n",err_code);
       return main_sys_exit(err_code);
}

int init_module()
{
       main_sys_exit=sys_table[__NR_exit];
       sys_table[__NR_exit]=alt_exit_function;
}
void cleanup_module()
{
       sys_table[__NR_exit]=main_sys_exit;
}

and this is the Makefile

Code:

obj-m += sample21.o
all: 
        make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
clean: 
        make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean

I got it working with a warning

Code:

make -C /lib/modules/2.6.28-11-generic/build M=/home/tkmsr/exer modules
make[1]: Entering directory `/usr/src/linux-headers-2.6.28-11-generic'
  CC [M]  /home/tkmsr/exer/sample21.o
/home/tkmsr/exer/sample21.c: In function ‘init_module’:
/home/tkmsr/exer/sample21.c:17: warning: control reaches end of non-void function
  Building modules, stage 2.
  MODPOST 1 modules
WARNING: "sys_table" [/home/tkmsr/exer/sample21.ko] undefined!
  CC      /home/tkmsr/exer/sample21.mod.o
  LD [M]  /home/tkmsr/exer/sample21.ko

Where as the program given in book is

Code:

#include <linux/kernel.h>
#include <linux/module.h>
#include <sys/syscall.h>
extern void *sys_table[];
asmlinkage int(*main_sys_exit)(int);
asmlinkage int alt_exit_function(int err_code)
{
        printk("Sys_exit called with err_code=%d\n",err_code);
        return main_sys_exit(err_code);
}

int init_module()
{
        main_sys_exit=sys_table[__NR_exit];
        sys_table[__NR_exit]=alt_exit_function;
}
void cleanup_module()
{
        sys_table[__NR_exit]=main_sys_exit;
}

and the Makefile (book says to go by gcc not Makefile)

Code:

obj-m += sample2.o
all: 
        make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
clean: 
        make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean

again failed.With following errors

Code:

make -C /lib/modules/2.6.28-11-generic/build M=/home/tkmsr/exer modules
make[1]: Entering directory `/usr/src/linux-headers-2.6.28-11-generic'
  CC [M]  /home/tkmsr/exer/sample2.o
/home/tkmsr/exer/sample2.c:3:25: error: sys/syscall.h: No such file or directory
/home/tkmsr/exer/sample2.c: In function ‘init_module’:
/home/tkmsr/exer/sample2.c:14: error: ‘__NR_exit’ undeclared (first use in this function)
/home/tkmsr/exer/sample2.c:14: error: (Each undeclared identifier is reported only once
/home/tkmsr/exer/sample2.c:14: error: for each function it appears in.)
/home/tkmsr/exer/sample2.c: In function ‘cleanup_module’:
/home/tkmsr/exer/sample2.c:19: error: ‘__NR_exit’ undeclared (first use in this function)
make[2]: *** [/home/tkmsr/exer/sample2.o] Error 1
make[1]: *** [_module_/home/tkmsr/exer] Error 2
make[1]: Leaving directory `/usr/src/linux-headers-2.6.28-11-generic'
make: *** [all] Error 2

knudfl · 08-24-2010, 11:38 AM

Quote:

error: sys/syscall.h: No such file or directory

sudo apt-get install libc6-dev

.. will provide : /usr/include/sys/syscall.h
..

tkmsr · 08-24-2010, 01:16 PM

Code:

sudo apt-get install libc6-dev
[sudo] password for tkmsr: 
Reading package lists... Done
Building dependency tree       
Reading state information... Done
libc6-dev is already the newest version.
0 upgraded, 0 newly installed, 0 to remove and 115 not upgraded.

Sergei Steshenko · 08-24-2010, 02:10 PM

Quote:

Originally Posted by tkmsr

Code:

sudo apt-get install libc6-dev
[sudo] password for tkmsr: 
Reading package lists... Done
Building dependency tree       
Reading state information... Done
libc6-dev is already the newest version.
0 upgraded, 0 newly installed, 0 to remove and 115 not upgraded.

There is nothing new - find where the file actually is, provide 'gcc' with the needed search place.

tkmsr · 08-24-2010, 09:29 PM

Why do I have to do it like this?
In any other program I did not had to do it like this.

Sergei Steshenko · 08-25-2010, 06:21 AM

Quote:

Originally Posted by tkmsr

Why do I have to do it like this?
In any other program I did not had to do it like this.

The answers are:

C99 standard
the program's author

.

You can't change the standard, but you can pick another program to play with.