[PATCH 1/1] doc: describe Kconfig fragments

[Heinrich Schuchardt]

In the 'Build with GCC' chapter mention Kconfig fragments and show how they
are applied.

Adjust the formatting in the configuration section to consistently use
italics for file names.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
---
 doc/build/gcc.rst | 35 ++++++++++++++++++++++++++++++-----
 1 file changed, 30 insertions(+), 5 deletions(-)

diff --git a/doc/build/gcc.rst b/doc/build/gcc.rst
index a0650a51db..40fe207890 100644
--- a/doc/build/gcc.rst
+++ b/doc/build/gcc.rst
@@ -74,21 +74,46 @@ beforehand. Please, refer to the board specific documentation
 Configuration
 -------------
 
-Directory configs/ contains the template configuration files for the maintained
-boards following the naming scheme::
+Directory *configs/* contains the template configuration files for the
+maintained boards following the naming scheme::
 
     <board name>_defconfig
 
 These files have been stripped of default settings. So you cannot use them
 directly. Instead their name serves as a make target to generate the actual
-configuration file .config. For instance the configuration template for the
-Odroid C2 board is called odroid-c2_defconfig. The corresponding .config file
-is generated by
+configuration file *.config*. For instance the configuration template for the
+Odroid C2 board is called *odroid-c2_defconfig*. The corresponding *.config*
+file is generated by
 
 .. code-block:: bash
 
     make odroid-c2_defconfig
 
+For some of the boards configuration fragments exist in directory *configs/*
+which can be used to modify the generated *.config* file. These are named::
+
+    <fragment name>.config
+
+They are applied to the current configuration file *.config* using the make
+command. E.g. the LG X3 T30 device family uses fragments for board specific
+configuration while providing a single defconfig file for the device family:
+
+.. code-block:: bash
+
+    # Generate device family .config file
+    make x3_t30_defconfig
+    # Apply board specific configuration fragment
+    make p895.config
+
+You can use a single command instead.
+
+.. code-block:: bash
+
+    make x3_t30_defconfig p895.config
+
+Details about available configuration fragments are provided in the
+:doc:`board specific documentation<../board/index>`.
+
 You can adjust the configuration using
 
 .. code-block:: bash
-- 
2.40.1