[yocto] How do I patch the kernel before it is built?

[Bruce Ashfield]

On 12-01-31 11:45 AM, autif khan wrote:
> I could not find a way to patch the kernel source before its is built.
>
> I promise to update the Yocto wiki's How do I section when I have a
> working solution for the following :-)

This should be covered in the existing documentation and also the
more general bitbake/oe-core docs.

>
> Here is what I am trying to do:
>
> 1) Patch the kernel (add VID/PID to hid_ignore_list in
> drivers/hid/hid-core.c and also to add the VID/PID to .h file)
> 2) Build the kernel - no change here - standard kernel build
> 3) Build a kernel module
>
> I have a meta layer where I am keeping my changes. I am guessing that I need to:
>
> a) write a bbappend file to accomplish #1
> b) write a recipe to accomplish #3
>
> I have written recipes before, but just for libraries and autotools
> based applications. Not for a kernel module. If there is a recipe out
> there for some other module, I would be happy to steal from it.
>
> Please advise how I can go about patching the kernel and if there is a

It's just like any other package. If your changes are simple, then
generating patches and putting them on the SRC_URI via a bbappend in
your layer is all you need. If you have complex changes, there are options
to manage them via git or via feature descriptions.

> recipe for a kernel module - please point me to it.

Darren validated and updated the kernel module example, so he'd probably
got this closer at hand than I do.

Cheers,

Bruce

>
> Thank you
>
> Autif
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