Hi people,
I am new to kernel module writing and I base myself on the Linux Device Drivers book from O'reilly. I have written this simple module :
#include <linux/module.h>
int init_module(void)
{
printk("<1>Module inserted\n");
return 0;
}
void cleanup_module(void)
{
printk("<1>Module removed\n");
}
--------------------------------------------
And this is the Makefile :
KERNELDIR = /usr/src/linux
include $(KERNELDIR)/.config
CFLAGS = -D__KERNEL__ -DMODULE -I$(KERNELDIR)/include \
-O -Wall
ifdef CONFIG_SMP
CFLAGS += -D__SMP__ -DSMP
endif
all : moduletest.o
clean :
rm -f *.o *~ core
---------------------------------------------
And look at this :
bash-2.05b# make
gcc -D__KERNEL__ -DMODULE -I/usr/src/linux/include -O -Wall -c -o moduletest.o moduletest.c
bash-2.05b# insmod ./moduletest.o
insmod: error inserting './moduletest.o': -1 Invalid module format
Anyone know what needs to be added or changed for kernel 2.6, or maybe its simply my own mistake?
(By the way, if you know of a kernel-beginner mailing list that would be better suited about this, tell me)
Thanks a lot in advance,
Best regards,
Steve
On Tue, Jun 08, 2004 at 08:33:42PM -0400, Steve Hemond wrote:
> Hi people,
>
> I am new to kernel module writing and I base myself on the Linux Device Drivers book from O'reilly. I have written this simple module :
>
> #include <linux/module.h>
>
> int init_module(void)
> {
> printk("<1>Module inserted\n");
> return 0;
> }
>
> void cleanup_module(void)
> {
> printk("<1>Module removed\n");
> }
http://lwn.net/Articles/21817/
> And this is the Makefile :
>
> KERNELDIR = /usr/src/linux
>
> include $(KERNELDIR)/.config
>
> CFLAGS = -D__KERNEL__ -DMODULE -I$(KERNELDIR)/include \
> -O -Wall
>
> ifdef CONFIG_SMP
> CFLAGS += -D__SMP__ -DSMP
> endif
>
> all : moduletest.o
>
> clean :
> rm -f *.o *~ core
>
http://lwn.net/Articles/21823/
> And look at this :
>
> bash-2.05b# make
> gcc -D__KERNEL__ -DMODULE -I/usr/src/linux/include -O -Wall -c -o moduletest.o moduletest.c
> bash-2.05b# insmod ./moduletest.o
> insmod: error inserting './moduletest.o': -1 Invalid module format
http://kernel.org/pub/linux/utils/kernel/module-init-tools/
http://lwn.net/Articles/22197/ "Kernel version checking"
> Anyone know what needs to be added or changed for kernel 2.6, or maybe its simply my own mistake?
>
> (By the way, if you know of a kernel-beginner mailing list that would be better suited about this, tell me)
http://kernelnewbies.org/mailinglist.php3
$ echo subscribe kernelnewbies | mail [email protected]
> Thanks a lot in advance,
>
> Best regards,
>
> Steve
Arthur
Steve Hemond <[email protected]> writes:
> Hi people,
>
> I am new to kernel module writing and I base myself on the Linux Device Drivers book from O'reilly. I have written this simple module :
>
> #include <linux/module.h>
>
> int init_module(void)
> {
> printk("<1>Module inserted\n");
> return 0;
> }
>
> void cleanup_module(void)
> {
> printk("<1>Module removed\n");
> }
>
For some reason that's probably far too complicated for my little
brain it's getting more and more complicated to write custom
modules for 2.6.
Compile all with:
gcc -O2 -c hello.c -I /path/to/kernel/include
or
gcc -O2 -mcmodel=kernel -mno-red-zone -c hello.c -I /path/to/kernel/include
if you're using x86-64.
In 2.4 what worked was:
#define MODULE 1
#define __KERNEL__ 1
#include <linux/module.h>
int init_module(void)
{
printk("Hello world\n");
return 0;
}
Then in 2.6 it needed
#define MODULE 1
#define __KERNEL__ 1
#define KBUILD_MODNAME "hello"
#include <linux/module.h>
int init_module(void)
{
printk("Hello world\n");
return 0;
}
Now since 2.6.5 or so it needs:
/* MODULE is not needed anymore */
#define __KERNEL__1
#include <linux/module.h>
int init_module(void)
{
printk("Hello world\n");
return 0;
}
struct module __this_module
__attribute__((section(".gnu.linkonce.this_module"))) = {
.name = "hello",
.init = init_module,
};
I'm sure there will be more surprises in the future. Keep tuned.
-Andi
On Wed, Jun 09, 2004 at 11:47:58AM +0200, Andi Kleen wrote:
>
> Now since 2.6.5 or so it needs:
>
> /* MODULE is not needed anymore */
> #define __KERNEL__1
> #include <linux/module.h>
>
> int init_module(void)
> {
> printk("Hello world\n");
> return 0;
> }
>
> struct module __this_module
> __attribute__((section(".gnu.linkonce.this_module"))) = {
> .name = "hello",
> .init = init_module,
> };
Most of the glue above can be deleted if you just accept to use kbuild when
building modules.
So to compile your module use a simple Makefile:
obj-m := mymodule.o
Then to compile the module use:
make -C path/to/kernel/src M=`pwd`
And to install it use:
make -C path/to/kernel/src M=`pwd` modules_install
And to clean up in the directory where the module is being compiled:
make -C path/to/kernel/src M=`pwd` clean
Sam