need help to start kernel module programming

[vnykr]

These two files i have created in som efolder in home dir
1)hello-1.c
2)Makefile


#include <linux/module.h> /* Needed by all modules */
#include <linux/kernel.h> /* Needed for KERN_INFO */
int init_module(void)
{
printk(KERN_INFO "Hello world 1.\n");
/*
* A non 0 return means init_module failed; module can't be loaded.
*/
return 0;
}
void cleanup_module(void)
{
printk(KERN_INFO "Goodbye world 1.\n");
}



---------------------------------------------------------------------------

Makefile:

obj−m += hello−1.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



------------------------------------------------------------------------------

when i tried
$ make
make: Nothing to be done for `all'.


i tried to compile the c file directly with gcc.

it is not able to find kernel.h and module.h

then i gave the whole path . even then it is giving some library errors only .

How can i made this first step SUCCESSFULL.,

pls help me.. i am very much interested in learning kernel.

thanks & regards
-vinay

[Franklin52]

Place one real tab before a make statement (not spaces!):

obj−m += hello−1.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

Regards

[vnykr]

thanks franklin!

i changed the make file as u said. now it has started compiling the file.

still it is not successfully compiling. here is the error after doing "make"
--------------------------------------------------------------------------------------------------------
make -C /lib/modules/2.6.23.1-42.fc8 /build M=/root/myComp/research/linKer/hello-1 modules
make[1]: Entering directory `/lib/modules/2.6.23.1-42.fc8'
make[1]: *** No rule to make target `/build'. Stop.
make[1]: Leaving directory `/lib/modules/2.6.23.1-42.fc8'
make: *** [all] Error 2
--------------------------------------------------------------------------------------------------------

"[all] Error 2" where does the actual error happened...!

[amit4g]

Do you have the kernel sources (`uname -r`) under /lib/modules

i.e.
[amit@localhost modules]$ pwd
/lib/modules
[amit@localhost modules]$ ls `uname -r`/source
arch CREDITS Documentation include Kbuild MAINTAINERS Module.symvers REPORTING-BUGS sound usr
block crypto drivers init kernel Makefile net scripts System.map vmlinux
COPYING cscope.out fs ipc lib mm README security tmp vmlinux.o


~amit

[ashok449]

I suggest u to use below commands to compile ur module

#gcc -c -O2 -Wall -isystem /lib/modules/`uname -r`/build/include -D__KERNEL__ -DMODULE xxxxx.c

if ur trying #make it wont work , it works with #make modules and still it need to support loadable kernel module.

Anyhow go through Makefile programming once to understand

[vnykr]

Ashok! and amit thanQ.!
i wil go thru MAKE FILE programming .!

ashok ,.! i tried with ur string.! it gave me following error.

one thing is : "#make modules and still it need to support loadable kernel module."

i have heard this before .. currently i am using FC8 and KUBUNTU 7.04 linux= for practicing this stuff, How can me make a kernel.. to module loadable kerel???????

do we really need makefile programming?? before starting kernel programming??

================================================== ================
[root@localhost hello-1]# gcc -c -O2 -Wall -isystem /lib/modules/`uname -r`/build/include -D__KERNEL__ -DMODULE hello-1.c
In file included from /lib/modules/2.6.23.1-42.fc8/build/include/linux/prefetch.h:14,
from /lib/modules/2.6.23.1-42.fc8/build/include/linux/list.h:8,
from /lib/modules/2.6.23.1-42.fc8/build/include/linux/module.h:9,
from hello-1.c:1:
/lib/modules/2.6.23.1-42.fc8/build/include/asm/processor.h:83: error: ‘CONFIG_X86_L1_CACHE_SHIFT’ undeclared here (not in a function)
/lib/modules/2.6.23.1-42.fc8/build/include/asm/processor.h:83: error: requested alignment is not a constant
In file included from /lib/modules/2.6.23.1-42.fc8/build/include/linux/module.h:20,
from hello-1.c:1:
/lib/modules/2.6.23.1-42.fc8/build/include/asm/module.h:69:2: error: #error unknown processor family

[ashok449]

Makefile prograaming is simple all you need to do is understanding normal makefile and device driver makefile.


Re-compile kernel to support loadable modules

#make menuconfig --> check loadable kernel module support
#make
#make modules
#make modules_install

try
#make help --for more

Go through any document on Kernel compilation before you start, just google..

[vnykr]

thanks Ashok..

on emistake i have done in make file.

i included a space b4 /build.
"make −C /lib/modules/$(shell uname −r)/build M=$(PWD) modules"

all .o .ko files are created..


thanks alot .!

[vnykr]

ashok1

jus now i have done insmod hello-1.ko

now os is behaving strangely
keys are not functioning well. greater than symbol is not working .. same with grep symbol.

also.. when i tried to see in /proc/modules file. hello-1.ko is no where

even in modprobe it is not listed...
why is kernel behaving like this... did it gone panic.. .