Problem in First-Patch-Tutorial

[Greg KH]

On Mon, Mar 13, 2017 at 11:39:36AM +0530, SIMRAN SINGHAL wrote:
> On Mon, Mar 13, 2017 at 10:42 AM, Alexander Kapshuk
> <alexander.kapshuk at gmail.com> wrote:
> > On Mon, Mar 13, 2017 at 6:18 AM, SIMRAN SINGHAL
> > <singhalsimran0 at gmail.com> wrote:
> >> On Mon, Mar 13, 2017 at 12:05 AM, Alexander Kapshuk
> >> <alexander.kapshuk at gmail.com> wrote:
> >>> On Sun, Mar 12, 2017 at 8:20 PM, SIMRAN SINGHAL
> >>> <singhalsimran0 at gmail.com> wrote:
> >>>> On Sun, Mar 12, 2017 at 10:15 PM, Alexander Kapshuk
> >>>> <alexander.kapshuk at gmail.com> wrote:
> >>>>> On Sun, Mar 12, 2017 at 5:34 PM,  <valdis.kletnieks at vt.edu> wrote:
> >>>>>> On Sun, 12 Mar 2017 15:49:31 +0200, Alexander Kapshuk said:
> >>>>>>
> >>>>>>> Are these drivers, drivers/iio/dummy/{iio_dummy_evgen,iio_dummy}.ko,
> >>>>>>> something of your own making, as I'm not seeing them in the kernel
> >>>>>>> source tree?
> >>>>>>>
> >>>>>>> The 'modules_install' make target installs drivers that have been
> >>>>>>> compiled as modules as opposed to those compiled into the kernel, into
> >>>>>>> /lib/modules/`uname -r`. For your own modules added to the kernel
> >>>>>>> source tree, or built out-of-tree, that would involve putting
> >>>>>>> appropriate entries into  Kconfig and/or Makefiles.
> >>>>>>>
> >>>>>>> Modeprobe expects your module to be found in /lib/modules/`uname -r`.
> >>>>>>> Otherwise, your module won't get loaded.
> >>>>>>
> >>>>>> One other thing to remember is that although 'make modules_install' will
> >>>>>> take all the .ko files from in-tree modules and put them in their proper
> >>>>>> place in /lib/modules/`uname-r`  and then run 'depmod', many out-of-tree
> >>>>>> Makefiles manage to forget to do that last step.
> >>>>>>
> >>>>>> modprobe is a wrapper around insmod - and the file produced by 'depmod'
> >>>>>> are what the wrapper uses to find the module.
> >>>>>
> >>>>> Thanks for elaborating on that.
> >>>>
> >>>> Still not working
> >>>>
> >>>> First I executed following commands:-
> >>>>
> >>>> $ make drivers/iio/dummy/iio_dummy_evgen.ko
> >>>> $ make drivers/iio/dummy/iio_dummy.ko
> >>>>
> >>>> Above commands executed successfully
> >>>>
> >>>> Then I run following command:
> >>>> $ insmod iio_dummy_evgen.ko
> >>>>
> >>>> Getting following error:
> >>>> insmod: ERROR: could not load module iio_dummy_evgen.ko: No such file
> >>>> or directory
> >>>>
> >>>> And, then I try executing them from driver/staging/dummy and then I
> >>>> got this error:
> >>>> insmod: ERROR: could not insert module iio_dummy_evgen.ko: Operation
> >>>> not permitted
> >>>
> >>> You have to run insmod as user root. Either specify the full path to
> >>> your module, or cd into the directory where the module is and run
> >>> insmod from there.
> >>
> >> I tried this before also but as you said I tried it again:
> >> # insmod iio_dummy_evgen.ko
> >> insmod: ERROR: could not insert module iio_dummy_evgen.ko: Invalid module format
> >>
> >> Now, I am getting this error.
> >
> > Sounds like your kernel module has been compiled for kernel sources
> > whose version is different to the version of the kernel you are trying
> > to load your module into.
> >
> > See http://www.tldp.org/LDP/lkmpg/2.6/html/x380.html for details.
> >
> > In other words, the version output by 'uname -r' must match the
> > version output by 'modinfo iio_dummy_evgen.ko | grep vermagic'.
> 
> Hi,
> 
> The problem is same you got, I have different versions of uname-r and the
> version output I got through vermagic.
> 
> # modinfo iio_dummy_evgen.ko
> filename:
> /home/simran/git/kernels/staging/drivers/iio/dummy/iio_dummy_evgen.ko
> license:        GPL v2
> description:    IIO dummy driver
> author:         Jonathan Cameron <jic23 at kernel.org>
> srcversion:     A8AC238EC07833E018CAF7B
> depends:        industrialio
> intree:         Y
> vermagic:       4.11.0-rc1+ SMP mod_unload modversions
> 
> 
> $ uname -r
> 4.10.0-rc3+
> 
> How to deal with this?

You did look in the kernel log when modprobe or insmod failed, right?
It should tell you what went wrong.

As others pointed out, you need to build your module against the kernel
you are running.

good luck!

greg k-h