kernel-dev: document KCONFIG_MODE

(From yocto-docs rev: 12aa6f9c6af68ea03fbb056677213b00d693cf5f)

Signed-off-by: Daniel Wagenknecht <dwagenknecht@emlix.com>
Reviewed-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
Reviewed-by: Quentin Schulz <foss@0leil.net>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/documentation/kernel-dev/common.rst b/documentation/kernel-dev/common.rst
index 3f35d8412f..5935d6f560 100644
--- a/documentation/kernel-dev/common.rst
+++ b/documentation/kernel-dev/common.rst
@@ -650,6 +650,15 @@ extends the :term:`FILESPATH`
 variable (search directories) to include the ``${PN}`` directory you
 created to hold the configuration changes.
 
+You can also use a regular ``defconfig`` file, as generated by the
+:ref:`ref-tasks-savedefconfig`
+task instead of a complete ``.config`` file. This only specifies the
+non-default configuration values.  You need to additionally set
+:term:`KCONFIG_MODE`
+in the linux-yocto ``.bbappend`` file in your layer::
+
+   KCONFIG_MODE = "alldefconfig"
+
 .. note::
 
    The build system applies the configurations from the ``defconfig``