Compiling dependent module

Compiling dependent module

[Devesh Sharma]

[-- Attachment #1: Type: text/plain, Size: 621 bytes --]

Hello all,

I have a situation where, I have one parent module in ../hello/
directory which exports one symbol (g_my_export). I have a dependent
module in ../hello1/ directory. Both have it's own makefiles.
Compiling of parent module (hello.ko) is fine, but during compilation
of dependent module (hello1.ko) I see a warning that g_my_export is
undefined.

On the other hand when I do depmod -a and modprobe, dependent module
inserts successfully in kernel.

I want to remove compile time warning. What should I do?

The source and makefile of both parent and dependent module is
attached with this mail.

Thanks
Devesh.

[-- Attachment #2: hello.c --]
[-- Type: text/x-csrc, Size: 346 bytes --]

#include <linux/init.h>
#include <linux/module.h>
MODULE_LICENSE("Dual BSD/GPL");

int g_my_export = 0xA ;

static int hello_init(void)
{
printk(KERN_ALERT "Hello, world\n");
return 0;
}
static void hello_exit(void)
{
printk(KERN_ALERT "Goodbye, cruel world\n");
}

EXPORT_SYMBOL(g_my_export) ;

module_init(hello_init);
module_exit(hello_exit);

[-- Attachment #3: Makefile --]
[-- Type: application/octet-stream, Size: 486 bytes --]

# If KERNELRELEASE is defined, we've been invoked from the
# kernel build system and can use its language.
ifneq ($(KERNELRELEASE),)
obj-m := hello.o
# Otherwise we were called directly from the command
# line; invoke the kernel build system.
else
KERNELDIR ?= /lib/modules/$(shell uname -r)/build

PWD := $(shell pwd)

default:
	$(MAKE) -C $(KERNELDIR) M=$(PWD) modules

install:
	$(MAKE) -C $(KERNELDIR) M=$(PWD) modules_install

clean:
	$(MAKE) -C $(KERNELDIR) M=$(PWD) clean

endif

[-- Attachment #4: hello1.c --]
[-- Type: text/x-csrc, Size: 382 bytes --]

#include <linux/init.h>
#include <linux/module.h>
MODULE_LICENSE("Dual BSD/GPL");

extern int g_my_export ;

static int hello_init(void)
{
    printk(KERN_ALERT "Hello, world1\n");
    
    printk("Value in g_my_export=%d\n",g_my_export) ;
return 0;
}
static void hello_exit(void)
{
printk(KERN_ALERT "Goodbye, cruel world1\n");
}

module_init(hello_init);
module_exit(hello_exit);

[-- Attachment #5: Makefile --]
[-- Type: application/octet-stream, Size: 487 bytes --]

# If KERNELRELEASE is defined, we've been invoked from the
# kernel build system and can use its language.
ifneq ($(KERNELRELEASE),)
obj-m := hello1.o
# Otherwise we were called directly from the command
# line; invoke the kernel build system.
else
KERNELDIR ?= /lib/modules/$(shell uname -r)/build

PWD := $(shell pwd)

default:
	$(MAKE) -C $(KERNELDIR) M=$(PWD) modules

install:
	$(MAKE) -C $(KERNELDIR) M=$(PWD) modules_install

clean:
	$(MAKE) -C $(KERNELDIR) M=$(PWD) clean

endif

Re: Compiling dependent module

[Sam Ravnborg]

On Sat, Oct 07, 2006 at 05:42:47PM +0530, Devesh Sharma wrote:
> Hello all,
> 
> I have a situation where, I have one parent module in ../hello/
> directory which exports one symbol (g_my_export). I have a dependent
> module in ../hello1/ directory. Both have it's own makefiles.
> Compiling of parent module (hello.ko) is fine, but during compilation
> of dependent module (hello1.ko) I see a warning that g_my_export is
> undefined.
> 
> On the other hand when I do depmod -a and modprobe, dependent module
> inserts successfully in kernel.
> 
> I want to remove compile time warning. What should I do?

Compile both module in same go.
See Documentation/kbuild/modules.txt for a description.

In short create a kbuild file that points to both modules
so kbuild knows about both modules when it builds them.

	Sam

Re: Compiling dependent module

[Devesh Sharma]

Hello sam, thanks for replying,

I have another doubt in the same,
generally when we compile any external kernel module which uses some
kernel symbol, there we don't see any such warnings even though we are
compiling our module separately?  So compiling a dependent module
separately is similar to compiling a external kernel module.
Why such warninigs are being observed here in dependent module while compiling?

On 10/7/06, Sam Ravnborg <sam@ravnborg.org> wrote:
> On Sat, Oct 07, 2006 at 05:42:47PM +0530, Devesh Sharma wrote:
> > Hello all,
> >
> > I have a situation where, I have one parent module in ../hello/
> > directory which exports one symbol (g_my_export). I have a dependent
> > module in ../hello1/ directory. Both have it's own makefiles.
> > Compiling of parent module (hello.ko) is fine, but during compilation
> > of dependent module (hello1.ko) I see a warning that g_my_export is
> > undefined.
> >
> > On the other hand when I do depmod -a and modprobe, dependent module
> > inserts successfully in kernel.
> >
> > I want to remove compile time warning. What should I do?
>
> Compile both module in same go.
> See Documentation/kbuild/modules.txt for a description.
>
> In short create a kbuild file that points to both modules
> so kbuild knows about both modules when it builds them.
>
>         Sam
>