Yocto SDK missing kernel header files [duplicate] - yocto

Question

This question already has an answer here:
How to build linux kernel module using Yocto SDK?
(1 answer)
Closed 1 year ago.
I have a kernel module that I have successfully compiled against my toolchain and installed in the image. The driver loads just fine and functions as expected. The user program that uses the driver is a cmake project in CLion 2020.1. I set up the cmake project to point to the OEToolchainConfig.cmake so all the
#include<foo.h>
are resolved. All except a number of kernel headers; for example: <linux/devices.h>
Edit
To be clear, there are linux header files that are resolved. for example:
#include <linux/kernel.h>
#include <linux/module.h>
I only seem to be missing a subset of kernel header files...
end Edit
After navigating to the sysroot toolchain /usr/includes/linux directory I verified the missing/unresolved kernel headers are in fact not present.
So, there are 2 questions here: 1) How did I successfully compile the driver against the toolchain if the required kernel headers are missing & 2) how do I include the missing kernel headers in the SDK?
I suspect the answer to the first question is that bitbake grabbed the host's kernel header files in which case question 1 becomes how do I prevent that from happening; just a guess though. For question 2 (my main question), after probing the google machine, I found references to add:
IMAGE_INSTALL += "\
kernel-devsrc \
linux-libc-headers-dev \
python"
to my core-image-myimage_1.0.bb file but this does not seem to add the headers I require.
Update
It would appear the header files i require are in fact installed into the tool chain but they are installed under source: /usr/src/kernel/include/linux
while this allows me a workaround for setting up include paths in CLion, is there some reason I cannot get these to install into the regular:/usr/include/linux directroy?

Answer 1

The generated SDK by default usually does not include the kernel headers. This is very similar to other systems like Ubuntu, where there is a separate package you must install first to compile against the kernel.
By putting kernel-devsrc in IMAGE_INSTALL, you added the kernel headers to the image but not the SDK. This is handy though, if you want to be able to compile and test your module on a running target (which is great for speeding up debugging).
Now with some context out of the way, take a look at this answer to see how to get the kernel headers in your SDK, and how to actually get compiling working. The latter not being so intuitive if you're a Linux newbie such as myself.
https://stackoverflow.com/a/67335209/1385815