Bitbake append file to reconfigure kernel

Question

I'm trying to reconfigure some .config variables to generate a modified kernel with wifi support enabled. The native layer/recipe for the kernel is located in this directory:

    meta-layer/recipes-kernel/linux/linux-yocto_3.19.bb

First I reconfigure the native kernel to add wifi support (for example, adding CONFIG_WLAN=y):

    $ bitbake linux-yocto -c menuconfig

After that, I generate a "fragment.cfg" file:

    $ bitbake linux-yocto -c diffconfig

I have created this directory into my custom-layer:

    custom-layer/recipes-kernel/linux/linux-yocto/

I have copied the "fragment.cfg file into this directory:

    $ cp fragment.cfg custom-layer/recipes-kernel/linux/linux-yocto/

I have created an append file to customize the native kernel recipe:

    custom-layer/recipes-kernel/linux/linux-yocto_3.19.bbappend

This is the content of this append file:

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

After that I execute the kernel compilation:

    $ bitbake linux-yocto -c compile -f

After this command, "fragment.cfg" file can be found into this working directory:

    tmp/work/platform/linux-yocto/3.19-r0

However none of the expected variables is active on the .config file (for example, CONFIG_WLAN is not set).

How can I debug this issue? What is supposed I'm doing wrong?

Answer 1

When adding this configuration you want to use append in your statement such as:

SRC_URI_append = "file://fragment.cfg"