Re: Regarding module init function

[Dave Hylands]

Hi Tobais,

On Thu, Jan 10, 2013 at 9:47 AM, Tobias Boege  wrote:
> On Tue, 08 Jan 2013, anish kumar wrote:
> > On Tue, 2013-01-08 at 14:51 +0100, Tobias Boege wrote:
...snip...
> > > On Tue, 08 Jan 2013, Rahul Bedarkar wrote:
> > > It's, too, in the init.h. There are two definitions of module_init()
> > > depending on whether MODULE is declared or not. The first definition
is
> > How does the individual driver define this MODULE?I think some macro
> > magic works here.
>
> I suppose that this is done through the invocation of the preprocessor,
> using -DMODULE depending on whether the target is built-in or a module.

Exactly.

--
Dave Hylands
Shuswap, BC, Canada
http://www.davehylands.com
___
Kernelnewbies mailing list
Kernelnewbies@kernelnewbies.org
http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

Re: Regarding module init function

[Tobias Boege]

On Tue, 08 Jan 2013, anish kumar wrote:
> On Tue, 2013-01-08 at 14:51 +0100, Tobias Boege wrote:
> > On Tue, 08 Jan 2013, Rahul Bedarkar wrote:
> > > Ok. in init/main.c we call do_basic_setup(). Where do_initcalls call each
> > > of init functions from __early_initcall_end to __initcall_end. But I don't
> > > know from where these values gets initialized.
> > > 
> > 
> > Take a look at include/linux/init.h. There you can find the macros for
> > declaring various init functions. They all go into special sections. The
> > rest is linker magic (e.g. arch/x86/kernel/vmlinux.lds{,.S}).
> > 
> > > I want to know when one of auxdriver (selected in from menuconfig) is 
> > > built
> > > as built-in module. When and Who calls it's init function ?
> > 
> > It's, too, in the init.h. There are two definitions of module_init()
> > depending on whether MODULE is declared or not. The first definition is
> How does the individual driver define this MODULE?I think some macro
> magic works here.

I suppose that this is done through the invocation of the preprocessor,
using -DMODULE depending on whether the target is built-in or a module.

Regards,
Tobi


___
Kernelnewbies mailing list
Kernelnewbies@kernelnewbies.org
http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

Re: Regarding module init function

[anish kumar]

On Tue, 2013-01-08 at 14:51 +0100, Tobias Boege wrote:
> On Tue, 08 Jan 2013, Rahul Bedarkar wrote:
> > Ok. in init/main.c we call do_basic_setup(). Where do_initcalls call each
> > of init functions from __early_initcall_end to __initcall_end. But I don't
> > know from where these values gets initialized.
> > 
> 
> Take a look at include/linux/init.h. There you can find the macros for
> declaring various init functions. They all go into special sections. The
> rest is linker magic (e.g. arch/x86/kernel/vmlinux.lds{,.S}).
> 
> > I want to know when one of auxdriver (selected in from menuconfig) is built
> > as built-in module. When and Who calls it's init function ?
> 
> It's, too, in the init.h. There are two definitions of module_init()
> depending on whether MODULE is declared or not. The first definition is
How does the individual driver define this MODULE?I think some macro
magic works here.
> accompanied by a useful comment about where the init function is called in
> either case.
> 
> Regards,
> Tobi
> 
> 
> ___
> Kernelnewbies mailing list
> Kernelnewbies@kernelnewbies.org
> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies



___
Kernelnewbies mailing list
Kernelnewbies@kernelnewbies.org
http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

Re: Regarding module init function

[Dave Hylands]

Hi Rahul,


On Tue, Jan 8, 2013 at 2:50 PM, Rahul Bedarkar  wrote:
>
> Thanks Dave!
>
> I just verified that from System.map. Between __early_initcall_end and
__initcall_end, there is list of init calls with levels from 0-7. What is
significance of these levels.

The levels basically just control the order that the initcalls are made.
Basically, all level 0 functions are called befor level 1 functions, etc.

The meaning behind the levels can be discerned from the macros in init.h
http://lxr.linux.no/#linux+v3.7.1/include/linux/init.h#L207

There is also some docs here:
http://lxr.linux.no/#linux+v3.7.1/Documentation/DocBook/kernel-hacking.tmpl#L736

Dave Hylands
___
Kernelnewbies mailing list
Kernelnewbies@kernelnewbies.org
http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

Re: Regarding module init function

[Tobias Boege]

On Tue, 08 Jan 2013, Rahul Bedarkar wrote:
> Ok. in init/main.c we call do_basic_setup(). Where do_initcalls call each
> of init functions from __early_initcall_end to __initcall_end. But I don't
> know from where these values gets initialized.
> 

Take a look at include/linux/init.h. There you can find the macros for
declaring various init functions. They all go into special sections. The
rest is linker magic (e.g. arch/x86/kernel/vmlinux.lds{,.S}).

> I want to know when one of auxdriver (selected in from menuconfig) is built
> as built-in module. When and Who calls it's init function ?

It's, too, in the init.h. There are two definitions of module_init()
depending on whether MODULE is declared or not. The first definition is
accompanied by a useful comment about where the init function is called in
either case.

Regards,
Tobi


___
Kernelnewbies mailing list
Kernelnewbies@kernelnewbies.org
http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

Re: Regarding module init function

[Rahul Bedarkar]

Thanks Dave!

I just verified that from System.map. Between __early_initcall_end
and __initcall_end, there is list of init calls with levels from 0-7. What
is significance of these levels.

Thanks,
Rahul

On Tue, Jan 8, 2013 at 7:01 PM, Dave Hylands  wrote:

> Hi,
>
>
>
> On Tue, Jan 8, 2013 at 11:08 AM, Rahul Bedarkar  wrote:
> >
> > Ok. in init/main.c we call do_basic_setup(). Where do_initcalls call
> each of init functions from __early_initcall_end to __initcall_end. But I
> don't know from where these values gets initialized.
>
> If you look here:
> http://lxr.linux.no/#linux+v3.7.1/include/linux/init.h#L279
>
> module_init is mapped to __initcall, which is in turn mapped to
> device_initcall, which sets up a pointer in a section called .initcall6.init
>
> If you then look in the kernel linker script:
> http://lxr.linux.no/#linux+v3.7.1/arch/arm/kernel/vmlinux.lds.S#L175
>
> INIT_CALLS is defined here:
> http://lxr.linux.no/#linux+v3.7.1/include/asm-generic/vmlinux.lds.h#L633
>
> and it defines the __initcall_start and __initcall_end symbols.
>
> Dave Hylands
>
___
Kernelnewbies mailing list
Kernelnewbies@kernelnewbies.org
http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

Re: Regarding module init function

[Dave Hylands]

Hi,


On Tue, Jan 8, 2013 at 11:08 AM, Rahul Bedarkar  wrote:
>
> Ok. in init/main.c we call do_basic_setup(). Where do_initcalls call each
of init functions from __early_initcall_end to __initcall_end. But I don't
know from where these values gets initialized.

If you look here:
http://lxr.linux.no/#linux+v3.7.1/include/linux/init.h#L279

module_init is mapped to __initcall, which is in turn mapped to
device_initcall, which sets up a pointer in a section called .initcall6.init

If you then look in the kernel linker script:
http://lxr.linux.no/#linux+v3.7.1/arch/arm/kernel/vmlinux.lds.S#L175

INIT_CALLS is defined here:
http://lxr.linux.no/#linux+v3.7.1/include/asm-generic/vmlinux.lds.h#L633

and it defines the __initcall_start and __initcall_end symbols.

Dave Hylands
___
Kernelnewbies mailing list
Kernelnewbies@kernelnewbies.org
http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

Re: Regarding module init function

[Rahul Bedarkar]

Ok. in init/main.c we call do_basic_setup(). Where do_initcalls call each
of init functions from __early_initcall_end to __initcall_end. But I don't
know from where these values gets initialized.

On Tue, Jan 8, 2013 at 2:10 PM, Rahul Bedarkar  wrote:

> I have gone through LDD3 page 31. But it didn't answer my question. It
> is describing module init and exit when manually loading driver and
> removing it.
> I want to know when one of auxdriver (selected in from menuconfig) is
> built as built-in module. When and Who calls it's init function ?
>
> Thanks,
> Rahul
>
> On Fri, Jan 4, 2013 at 6:52 PM, Tobias Boege wrote:
>
>> On Fri, 04 Jan 2013, Rahul Bedarkar wrote:
>> > Hi,
>> >
>> > This may be stupid question.
>> >
>> > When we compile external module and insert it, it's init function is
>> called
>> > and when we remove it, it's exit function gets called.
>> >
>> > What happens in case of built-in modules? When it's init and exit is
>> > called? May be take example of one of auxdriver.
>> >
>>
>> You can find relevant information in LDD3, pp. 31 ff.. Basically, there is
>> no difference in the use of the init function (it's called at kernel
>> startup, I suppose) but exit is simply discarded in this case, because if
>> your module is built-in, it could never be removed.
>>
>> Regards,
>> Tobi
>>
>>
>> ___
>> Kernelnewbies mailing list
>> Kernelnewbies@kernelnewbies.org
>> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>>
>
>
___
Kernelnewbies mailing list
Kernelnewbies@kernelnewbies.org
http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

Re: Regarding module init function

[Rahul Bedarkar]

I have gone through LDD3 page 31. But it didn't answer my question. It
is describing module init and exit when manually loading driver and
removing it.
I want to know when one of auxdriver (selected in from menuconfig) is built
as built-in module. When and Who calls it's init function ?

Thanks,
Rahul

On Fri, Jan 4, 2013 at 6:52 PM, Tobias Boege  wrote:

> On Fri, 04 Jan 2013, Rahul Bedarkar wrote:
> > Hi,
> >
> > This may be stupid question.
> >
> > When we compile external module and insert it, it's init function is
> called
> > and when we remove it, it's exit function gets called.
> >
> > What happens in case of built-in modules? When it's init and exit is
> > called? May be take example of one of auxdriver.
> >
>
> You can find relevant information in LDD3, pp. 31 ff.. Basically, there is
> no difference in the use of the init function (it's called at kernel
> startup, I suppose) but exit is simply discarded in this case, because if
> your module is built-in, it could never be removed.
>
> Regards,
> Tobi
>
>
> ___
> Kernelnewbies mailing list
> Kernelnewbies@kernelnewbies.org
> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>
___
Kernelnewbies mailing list
Kernelnewbies@kernelnewbies.org
http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

Re: Regarding module init function

[Tobias Boege]

On Fri, 04 Jan 2013, Rahul Bedarkar wrote:
> Hi,
> 
> This may be stupid question.
> 
> When we compile external module and insert it, it's init function is called
> and when we remove it, it's exit function gets called.
> 
> What happens in case of built-in modules? When it's init and exit is
> called? May be take example of one of auxdriver.
> 

You can find relevant information in LDD3, pp. 31 ff.. Basically, there is
no difference in the use of the init function (it's called at kernel
startup, I suppose) but exit is simply discarded in this case, because if
your module is built-in, it could never be removed.

Regards,
Tobi


___
Kernelnewbies mailing list
Kernelnewbies@kernelnewbies.org
http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies