[yocto] Building a Kernel Module that uses /lib/modules/<version>/build/Makefile

[Nicholas Krause]

On September 6, 2016 6:50:34 PM EDT, "Daniel." <danielhilst at gmail.com> wrote:
>Ronald
>
>If you have a module developed against 3.10 you may have trouble
>compiling it against 4.x. You should port the module to 4.x kernel,
>not kernel to module. If you patch the kernel to compile that module
>other modules may break. I suggest that you download the kernel and
>module to some folders outside of Yocto while developing, create one
>or more patches with the fixes and then use Yocto to apply that
>patches against that module.
>
>Cheers,
>
If the driver is open can I take a look. It may not be too much work depending on what tree your basing against. 
Nick
>2016-09-06 19:02 GMT-03:00 Ronald Oakes <ronaldo at brc2.com>:
>> I seem to have been able to solve my own problem by doing a bit more
>> poking around:
>>
>> It looks like the makefile I'm looking for is found in
>> ${STAGING_KERNEL_DIR}, which appears in the Makefile as
>> $(KERNEL_PATH).
>>
>> At least once I replaced the setting that was hard coded to
>> /lib/modules/$(KERNEL_VERSION/build with $(KERNEL_PATH), I'm getting
>a
>> build.  (I'm still getting some issues with the fact that my third
>> party source doesn't want to build wtih either kernels 4.1.18 or
>4.4.x
>> as they are both too new, so I may have to patch it's linux_common.h
>> to accept 4.1.18 instead of 4.1.1, but that is a minor issue in
>> comparison)
>>
>> Thank you
>>   Ron Oakes
>>
>> On Tue, Sep 6, 2016 at 11:11 AM, Ronald Oakes <ronaldo at brc2.com>
>wrote:
>>> I'm trying to integrate a 3rd party kernel module for some hardware
>>> that we are using as part of our project.  Following the directions
>>> that work on the native Linux installation for building it doesn't
>>> quite work for a number of reasons, so I'm now modifying the
>generated
>>> Makefile.
>>>
>>> However, it appears that the bulk of the work is done by a standard
>>> makefile located in /lib/modules/$(KERNEL_VERSION)/build (which was
>>> actually hard-coded by the configure before I started modifying the
>>> makefile).  But, I'm not able to locate this in the files that Yocto
>>> has produced when building the embedded kernel and the other kernel
>>> modules.
>>>
>>> I've not booted the target and looked there - but I'd rather not
>build
>>> this on the target.  Ideally, I'd like to have everything built on
>my
>>> development system (not that we won't have the horsepower to build
>on
>>> the target, but I'd rather not be putting the compilers there, nor
>>> have to be having a module build as part of bring up each time - we
>>> won't have any non-volitate memory so everything will have to be
>>> loaded each time we boot.
>>>
>>> Similarly, building the binary and just including that may be
>>> difficult as our build system is running a much older kernel than
>our
>>> target (3.10 versus 4.4), so we'd still be in a cross-target
>situation
>>> and the 3rd party supplier assumes that one is building for the
>system
>>> one is running on and provides limited support otherwise in their
>>> documentation (I've not contacted them for assistance yet)
>>>
>>> Any suggestions/recomendations?
>>>
>>> Ron Oakes
>> --
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