Problem in First-Patch-Tutorial

[Alexander Kapshuk]

On Mon, Mar 13, 2017 at 8:09 AM, SIMRAN SINGHAL
<singhalsimran0 at gmail.com> 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?

Your kernel version is 4.10.0-rc3, while your module was built for
kernel version 4.11.0-rc1, which is why it wouldn't load.
You have to either download the sources for kernel version 4.10.0-rc3,
and build your module against that, or build a new kernel using the
sources for version 4.11.0-rc1, build your module against that, reboot
into 4.11.0-rc1, and then load your module.