[kdev981]

My very first attempt to compile a simple kernel module has gone waste,

This is the code for the module:

//Our first kernel program!!
#include <linux/module.h>
#include <linux/kernel.h>

int init_module(void)
{
 printk("<1> Hello Kernel world!!");
 return 0;
}

void cleanup_module(void)
{
 printk(KERN_ALERT "Goodbye Kernel world!");
}

and the makefile

TARGET  := hello-1
WARN    := -W -Wall -Wstrict-prototypes -Wmissing-prototypes
INCLUDE := -isystem /lib/modules/`uname -r`/build/include
CFLAGS  := -O2 -DMODULE -D__KERNEL__ ${WARN} ${INCLUDE}
CC      := gcc

${TARGET}.o: ${TARGET}.c

.PHONY: clean

clean:
        rm -rf ${TARGET}.o

This is taken from the free ebook Linux Kernel Module programming.

and here's the output:

[root@localhost hello-1]# make
gcc -O2 -DMODULE -D__KERNEL__ -W -Wall -Wstrict-prototypes -Wmissing-prototypes -isystem /lib/modules/`uname -r`/build/include   -c -o hello-1.o 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:2:
/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:2:
/lib/modules/2.6.23.1-42.fc8/build/include/asm/module.h:69:2: error: #error unknown processor family
make: *** [hello-1.o] Error 1

I wonder how the processor family is unknown, since the same kernel is running on this machine (2.6.23.1-42.fc8 )

Please help!

[Franklin52]

Try this makefile, 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

[judepereira]

Delete everything inyour Makefile, and add this:

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

[phro]

Hi
Even i am working on my first hello world program in modifying the kernel. I have just began to get familiarized with linux, so i dont have a lot of practice with the makefiles.
This is my kernel program

#define MODULE
#include <linux/module.h>

int init_module(void)
{
printk("hello\n");
return 0;
}

void cleanup_module(void)
{
printk("bbye\n");
}

I have been trying to search for the makefile to use for this.
If i run the program using the gcc command (as stated in the book - O Reilly)

#gcc -c hello.c

usr/lib/gcc-lib/i386-redhat-linux/3.2.2/../../../crt1.o(.text+0x1: In function `_start':
../sysdeps/i386/elf/start.S:77: undefined reference to `main'
/tmp/cc6tY8ap.o(.text+0xf): In function `init_module':
: undefined reference to `printk'
/tmp/cc6tY8ap.o(.text+0x2c): In function `cleanup_module':
: undefined reference to `printk'
collect2: ld returned 1 exit status

the linux i am using presently is 2.4.20-8
I have tried to search about this error and similar pots online, but couldnt find anything. Could someone please help me with this? Or if similar question has been asked before to post the link so that i can get my program working

thanks in advance

gagan

[ashok449]

include these headers

#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>



and compile with
gcc -c -O2 -Wall -isystem /lib/modules/`uname -r`/build/include -D__KERNEL__ -DMODULE xxxx.c

spend some time on understanding that copile command it helps you a lot.

keep coding ...