Re: [Ltib] how to build a kernel module using ltib? (docu)

[David Warman]

Hi Stuart,

Thanks;

I thought videodev was part of the V4L subsystem and was handled by  
ltib, since it is not explicitly called out in the --configure menu,  
but does get built when I turn on V4L. So, in fact, I have no idea  
how videodev is being built because I am not doing that myself.

Most puzzling is the fact that I get different behaviors after a ltib  
--configure session even when I am sure I made o changes that should  
have affected it. In fact, the first time I turned on V4L everything  
seemed OK, not that I knew as much about testing that part at the  
time as I do now.

Re the modules I am going to be adding, thanks for the pointer to  
hello_mod, that will take me a long way.

While I have your ear, there is another puzzle: there seem to be two  
kernel config files involved - the one called out in the ltib menu:

ltib/config/platform/mpc8349itx/nas_linux-2.6.13.4-mpc8349itx.config


and the one that gets changed when I make changes in the kernel  
configure menu:

ltib/rootfs/lib/modules/2.6.13.4/build/.config

What is the relationship here? the first has CONFIG_KMOD off, the  
second has it =y. There are other differences too.


Thanks for your help with this,

David Warman

On Mar 19, 2007, at 7:36 AM, Stuart Hughes wrote:

> Hi David,
>
> You'll have to ask the maintainer of videodev how to build it, I'm not
> familiar with this.
>
> As far as ltib goes, there is a module example.  If you do:
>
> $ ./ltib hello_mod -m prep
>
> It will unpack a module example.  You can the take a look at the files
> in rpm/BUILD/hello_mod-1.2, which include:
> COPYING  Makefile  message_mod.c  mod_main.c  README
>
> The README has some explanations and also some links to further
> information regarding building modules.
>
> To actually build this example:
>
> $ ./ltib -p hello_mod
>
> If you're still having problems after then, please get back in  
> touch on
> the list.  You'll need to say how your building the videodev module.
>
> Regards, Stuart
>
> On Fri, 2007-03-16 at 17:19 -0700, David Warman wrote:
> > Hi folks,
> >
> > <resend after subscribing to the list - sorry if this is then  
> > repeated>
> >
> > I am having a related problem: I am setting up to use the ov511
> > camera and the usbvideo usb capture device. Both depend on the
> > videodev module. When I modprobe videodev, I get "Unknown symbol
> > request_module" error and the probe fails. Yet I have verified that
> > kmod.o exports this label.  I am guessing that there is something
> > missing from the link commands for building videodev, but I have not
> > yet been able to find the file that contains that invocation. Forcing
> > as rebuild by deleting kmod.o and videodev.o does not fix the
> > problem. Has anybody any ideas on this?
> >
> > update:
> > I was getting this response to modprobe:
> >
> > 11:59 PM root DavesHybrid ~]$ modprobe videodev
> > videodev: Unknown symbol request_module
> > insmod: cannot insert `/lib/modules/2.6.13.4/kernel/drivers/media/
> > video/videodev.ko': Unknown symbol in module (-1): No such file or
> > directory
> > modprobe: failed to load module videodev
> >
> >
> > then I deleted videodev.o, ran ./ltib -- configure, forgot to check
> > kernel build, then ran it again with kernel build, and now I get this
> > response instead:
> >
> > [12:06 AM root DavesHybrid ~]$ modprobe videodev
> > modprobe: QM_MODULES: Function not implemented
> >
> > modprobe: QM_MODULES: Function not implemented
> >
> > modprobe: Can't locate module videodev
> > [12:07 AM root DavesHybrid ~]$ find / -name videodev.* -print
> > /lib/modules/2.6.13.4/kernel/drivers/media/video/videodev.ko
> >
> > [12:08 AM root DavesHybrid ~]$
> >
> >
> > Also, and btw, I think the sample_ltib_ko.tgz would be a great help,
> > but it does not show as a link; where would I find it?
> >
> >
> > thanks in advance,
> >
> > David Warman
> >
> >
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> >
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