doc: application: Explain Zephyr application CMakeLists.txt
Add descriptions for each line in application's CMakeLists.txt. Since
this is the first time a new user is exposed to Zephyr applications
CMakeLists.txt, it's a good time to explain why each line exists.
The descriptions must be for both new Zephyr developers with or
without CMake knowledge.
This commit also moves the comment lines from CMakeLists.txt to the
descriptions to make the file simpler.
ref. #39014
Signed-off-by: Yasushi SHOJI <yashi@spacecubics.com>
Co-authored-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>
diff --git a/doc/application/index.rst b/doc/application/index.rst
index c71002a..bb59b8c 100644
--- a/doc/application/index.rst
+++ b/doc/application/index.rst
@@ -219,22 +219,30 @@
.. code-block:: cmake
- # Find Zephyr. This also loads Zephyr's build system.
- cmake_minimum_required(VERSION 3.13.1)
+ cmake_minimum_required(VERSION 3.20.0)
+
find_package(Zephyr)
project(my_zephyr_app)
- # Add your source file to the "app" target. This must come after
- # find_package(Zephyr) which defines the target.
target_sources(app PRIVATE src/main.c)
- ``find_package(Zephyr)`` sets the minimum CMake version and pulls in the
- Zephyr build system, which creates a CMake target named ``app`` (see
- :ref:`cmake_pkg`). Adding sources to this target is how you include them in
- the build.
+ ``cmake_minimum_required()`` is required to be in your
+ :file:`CMakeListst.txt` by CMake. It is also invoked by the Zephyr
+ package. The most recent of the two versions will be enforced by CMake.
- .. note:: ``cmake_minimum_required()`` is also invoked by the Zephyr package.
- The most recent of the two versions will be enforced by CMake.
+ ``find_package(Zephyr)`` pulls in the Zephyr build system, which creates a
+ CMake target named ``app`` (see :ref:`cmake_pkg`). Adding sources to this
+ target is how you include them in the build. The Zephyr package will define
+ ``Zephyr-Kernel`` as a CMake project and enable support for the ``C``,
+ ``CXX``, ``ASM`` languages.
+
+ ``project(my_zephyr_app)`` is required for defining your application
+ project. This must be called after ``find_package(Zephyr)`` to avoid
+ interference with Zephyr's ``project(Zephyr-Kernel)``.
+
+ ``target_sources(app PRIVATE src/main.c)`` is to add your source file to the
+ ``app`` target. This must come after ``find_package(Zephyr)`` which defines
+ the target.
#. Set Kconfig configuration options. See :ref:`application-kconfig`.
