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

[Ronald Oakes]

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