[meta-xilinx] Add kernel configuration options using configuration fragments in custom layer

[Alan Levy]

You're missing the SCC file, see https://www.yoctoproject.org/docs/2.4.1/kernel-dev/kernel-dev.html#adding-recipe-space-kernel-features. Inside the SCC file you include a reference to the CFG file, for example:

	define KFEATURE_DESCRIPTION "Kernel configuration fragments"
	define KFEATURE_COMPATIBILITY board
	kconf hardware fragments.cfg


ALAN LEVY, Lead Consultant, Embedded Systems

Plextek Consulting, The Plextek Building, London Road, Great Chesterford, Saffron Walden, CB10 1NY, UK
T: +44 (0) 1799 533200    E: alan.levy at plextek.com  W: www.plextek.com




-----Original Message-----
From: Artjom Rjabov [mailto:artik6 at yandex.com] 
Sent: 26 April 2018 16:18
To: meta-xilinx at yoctoproject.org
Subject: [meta-xilinx] Add kernel configuration options using configuration fragments in custom layer

I am currently trying to modify the kernel configuration (overwrite default xilinx-linux layer configs) by adding configuration fragments to my custom layer like this :

linux-xlnx_%.bbappend file:

> FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}"
> SRC_URI =+ "file://fragments.cfg"

fragments.cfg:

> CONFIG_I2C_SLAVE = y

Then I run "bitbake \my-image\" and it parses the fragment perfectly, but it doesn't look like it ends up in the final config.

mismatch-all.txt:

> Config: CONFIG_I2C_SLAVE
> From: <path-to>/poky/build/tmp/work-shared/zedboard-zynq7/kernel-source/.kernel-meta/configs/fragments.cfg
> Requested value:  CONFIG_I2C_SLAVE = y
> Actual value:     # CONFIG_I2C_SLAVE is not set

How to tell bitbake to use my config parameters over the default ones? Actually, there are a lot of parameters in the "mismatch-all" from different config files scattered all across "kernel-source" directory. What is the priority?

Additionally, I tried to use SCC file with kconf, but it changes nothing. It displays a warning during compilation: "specified values did not make it into the kernel's final configuration: CONFIG_I2C_SLAVE". Same thing, but with a proper warning.