Link lib to a kernel module

Link lib to a kernel module

[Matthias Fechner]

Hi,

I tried today to link a lib (.a) to my kernel module but I could not
found howto do it.
I prepared a little example:
hello.c:
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/io.h>
#include <linux/version.h>
#include "hello_lib.h"

MODULE_LICENSE("GPL");

int init_module(void)
{
   printHello();
   return 0;
}
	   
void cleanup_module(void)
{
   printk("remove module\n");
   return;
}

hello_lib.c:
int helloWorld(void)
{
   printk("Hello World\n");
   return 0;
}

hello_lib.h:
int helloWorld(void);

Makefile:
KDIR    := /lib/modules/$(shell uname -r)/build
PWD := $(shell pwd)
EXTRA_CFLAGS+=-I/usr/home/idefix/programming/kernel_hello_world_lib/

obj-m := hello.o
hello-obj := hello.o libarinc653.a

all:
        gcc -c -o hello_lib.o hello_lib.c
        rm -f libhello_lib.a
        ar cru libhello_lib.a hello_lib.o
        $(MAKE) -C $(KDIR) SUBDIRS=$(PWD) modules

Can please someone help me here?

Thx a lot,
Matthias

-- 

"Programming today is a race between software engineers striving to
build bigger and better idiot-proof programs, and the universe trying to
produce bigger and better idiots. So far, the universe is winning." --
Rich Cook

Re: Link lib to a kernel module

[Dipti Ranjan Tarai]

Hi,
   As per my knowledge kernel module can not access to a library 
function. Library function are only accessible to user level program. 
Module can access exported symbol only.

Regards
Dipti Ranjan Tarai

Matthias Fechner wrote:
> Hi,
>
> I tried today to link a lib (.a) to my kernel module but I could not
> found howto do it.
> I prepared a little example:
> hello.c:
> #include <linux/kernel.h>
> #include <linux/module.h>
> #include <linux/io.h>
> #include <linux/version.h>
> #include "hello_lib.h"
>
> MODULE_LICENSE("GPL");
>
> int init_module(void)
> {
>    printHello();
>    return 0;
> }
> 	   
> void cleanup_module(void)
> {
>    printk("remove module\n");
>    return;
> }
>
> hello_lib.c:
> int helloWorld(void)
> {
>    printk("Hello World\n");
>    return 0;
> }
>
> hello_lib.h:
> int helloWorld(void);
>
> Makefile:
> KDIR    := /lib/modules/$(shell uname -r)/build
> PWD := $(shell pwd)
> EXTRA_CFLAGS+=-I/usr/home/idefix/programming/kernel_hello_world_lib/
>
> obj-m := hello.o
> hello-obj := hello.o libarinc653.a
>
> all:
>         gcc -c -o hello_lib.o hello_lib.c
>         rm -f libhello_lib.a
>         ar cru libhello_lib.a hello_lib.o
>         $(MAKE) -C $(KDIR) SUBDIRS=$(PWD) modules
>
> Can please someone help me here?
>
> Thx a lot,
> Matthias
>
>   

Re: Link lib to a kernel module

[Matthias Fechner]

Hi,

Dipti Ranjan Tarai schrieb:
>   As per my knowledge kernel module can not access to a library
> function. Library function are only accessible to user level program.
> Module can access exported symbol only.

I don't want to build the module against a shared lib. I have here a lib
and I want that the lib is included into the kernel module.
I found in the documentation that it is possible to link the kernel
module with several object files (.o) and I found no source to do it
with libs (.a).

Thx
Matthias

-- 

"Programming today is a race between software engineers striving to
build bigger and better idiot-proof programs, and the universe trying to
produce bigger and better idiots. So far, the universe is winning." --
Rich Cook

Re: Link lib to a kernel module

[Matthias Fechner]

Hello Dipti,

* Dipti Ranjan Tarai <dipti@innomedia.soft.net> [25-10-06 11:16]:
> Now in mod2 call test_export() of mod1, compile it and load the module u 
> can able to access test_export().

thx for that hint, but I want one module :)

I was now successfull with the following code:
hello_lib.h:
int printHello(int);

hello_lib.c
int printHello(int count)
{
   int i;
      
   for(i=0;i<=count;i++)
   {
      printk("Hello World\n");
   }
		        
   return 0;
}
			   
hello.c:
#include <linux/kernel.h>
#include <linux/module.h>
#include "hello_lib.h"
			   
MODULE_LICENSE("GPL");
			   
int init_module(void)
{
    printk("call function\n");
    printHello(5);
    return 0;
}
				    
void cleanup_module(void)
{
    printk(KERN_INFO "remove module\n");
    return;
}
					  
Makefile:
KDIR    := /lib/modules/$(shell uname -r)/build
PWD := $(shell pwd)

obj-m += test.o
test-y := hello.o libhello_lib.a

all:
    gcc -I/usr/include -c -o hello_lib.o hello_lib.c
    rm -f libhello_lib.a
    ar cru libhello_lib.a hello_lib.o
    $(MAKE) -C $(KDIR) SUBDIRS=$(PWD) modules KBUILD_VERBOSE=1
				      

Best regards,
Matthias

-- 

"Programming today is a race between software engineers striving to
build bigger and better idiot-proof programs, and the universe trying to
produce bigger and better idiots. So far, the universe is winning." --
Rich Cook

Re: Link lib to a kernel module

[Oleg Verych]

Hallo, Matthias.

On 2006-10-24, Matthias Fechner wrote:

> I tried today to link a lib (.a) to my kernel module but I could not
> found howto do it.

`Documentation/kbuild' directory in your linux sources.
`makefiles.txt' about `lib-y',
`modules.txt'   about modules.

Good luck.
____

Re: [kbuild-devel] Link lib to a kernel module

[Matthias Fechner]

Hello Oleg,

* Oleg Verych <olecom@flower.upol.cz> [24-10-06 12:11]:
> `Documentation/kbuild' directory in your linux sources.
> `makefiles.txt' about `lib-y',
> `modules.txt'   about modules.

I was now successfull with:
hello_lib.h:
int printHello(int);

hello_lib.c
int printHello(int count)
{
   int i;
      
   for(i=0;i<=count;i++)
   {
       printk("Hello World\n");
   }
   return 0;
}
			   
hello.c:
#include <linux/kernel.h>
#include <linux/module.h>
#include "hello_lib.h"
   
MODULE_LICENSE("GPL");
			   
int init_module(void)
{
    printk("call function\n");
    printHello(5);
    return 0;
}
				    
void cleanup_module(void)
{
    printk(KERN_INFO "remove module\n");
    return;
}
					  
Makefile:
KDIR    := /lib/modules/$(shell uname -r)/build
PWD := $(shell pwd)

obj-m += test.o
test-y := hello.o libhello_lib.a

all:
   gcc -I/usr/include -c -o hello_lib.o hello_lib.c
   rm -f libhello_lib.a
   ar cru libhello_lib.a hello_lib.o
   $(MAKE) -C $(KDIR) SUBDIRS=$(PWD) modules KBUILD_VERBOSE=1
	      


Best regards,
Matthias

-- 

"Programming today is a race between software engineers striving to
build bigger and better idiot-proof programs, and the universe trying to
produce bigger and better idiots. So far, the universe is winning." --
Rich Cook

Re: Link lib to a kernel module

[Oleg Verych]

On 2006-10-25, Matthias Fechner wrote:
[]
> Makefile:
> KDIR    := /lib/modules/$(shell uname -r)/build
> PWD := $(shell pwd)

there's $(CURDIR), just in case...
____