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doc: restore environment variables page

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This was moved into the application development guide in commit
bf9ceac ("doc: move env_vars into application development").

That commit claimed the following rationale:

  No reason why we are duplicating this information in a standalone
  guide when we already talk about env variables in the application
  developer guide.

A github comment later says the duplication was in "Important build
system variables":

https://github.com/zephyrproject-rtos/zephyr/pull/34364#discussion_r616646517

This is incorrect and a misreading of the application development
guide.

The application development guide is talking about **cmake**
variables. These are not the same thing at all as **environment**
variables; treating them as if they are the same is simply wrong and
misleading, especially the "option 4" part that is really about
CMake variables, not environment variables.

In fact, the separate environment variables page was created for a
reason, which was to have a single place to explain to people unused
to managing their environment how things work, without cluttering
things up for people who already understand this.

There is nothing wrong with small, self-contained guides and in fact I
would argue they are a good thing.

Fix this confusing situation by restoring the original, separate page
and extricating the portions of it that are not related to environment
variables.

Signed-off-by: Martí Bolívar <marti.bolivar@nordicsemi.no>
This commit is contained in:
Martí Bolívar 2021-11-12 16:44:59 -08:00 • committed by Carles Cufí
commit 71f17bcbc2
4 changed files with 214 additions and 145 deletions
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155
doc/application/index.rst
View file

@ -253,146 +253,8 @@ Zephyr.)
``include($ENV{ZEPHYR_BASE}/cmake/app/boilerplate.cmake NO_POLICY_SCOPE)`` ``include($ENV{ZEPHYR_BASE}/cmake/app/boilerplate.cmake NO_POLICY_SCOPE)``
is still supported for backward compatibility with older applications. is still supported for backward compatibility with older applications.
Including ``boilerplate.cmake`` directly in the sample still requires to run Including ``boilerplate.cmake`` directly in the sample still requires using
``source zephyr-env.sh`` or execute ``zephyr-env.cmd`` before building the :ref:`zephyr-env` before building the application.
application.
.. _env_vars:
Setting Variables
*****************
Option 1: Just Once
====================
To set the environment variable :envvar:`MY_VARIABLE` to ``foo`` for the
lifetime of your current terminal window:
.. tabs::
.. group-tab:: Linux/macOS
.. code-block:: console
export MY_VARIABLE=foo
.. group-tab:: Windows
.. code-block:: console
set MY_VARIABLE=foo
.. warning::
This is best for experimentation. If you close your terminal window, use
another terminal window or tab, restart your computer, etc., this setting
will be lost forever.
Using options 2 or 3 is recommended if you want to keep using the setting.
Option 2: In all Terminals
==========================
.. tabs::
.. group-tab:: Linux/macOS
Add the ``export MY_VARIABLE=foo`` line to your shell's startup script in
your home directory. For Bash, this is usually :file:`~/.bashrc` on Linux
or :file:`~/.bash_profile` on macOS. Changes in these startup scripts
don't affect shell instances already started; try opening a new terminal
window to get the new settings.
.. group-tab:: Windows
You can use the ``setx`` program in ``cmd.exe`` or the third-party RapidEE
program.
To use ``setx``, type this command, then close the terminal window. Any
new ``cmd.exe`` windows will have :envvar:`MY_VARIABLE` set to ``foo``.
.. code-block:: console
setx MY_VARIABLE foo
To install RapidEE, a freeware graphical environment variable editor,
`using Chocolatey`_ in an Administrator command prompt:
.. code-block:: console
choco install rapidee
You can then run ``rapidee`` from your terminal to launch the program and set
environment variables. Make sure to use the "User" environment variables area
-- otherwise, you have to run RapidEE as administrator. Also make sure to save
your changes by clicking the Save button at top left before exiting.Settings
you make in RapidEE will be available whenever you open a new terminal window.
.. _env_vars_zephyrrc:
Option 3: Using ``zephyrrc`` files
==================================
Choose this option if you don't want to make the variable's setting available
to all of your terminals, but still want to save the value for loading into
your environment when you are using Zephyr.
.. tabs::
.. group-tab:: Linux/macOS
Create a file named :file:`~/.zephyrrc` if it doesn't exist, then add this
line to it:
.. code-block:: console
export MY_VARIABLE=foo
To get this value back into your current terminal environment, **you must
run** ``source zephyr-env.sh`` from the main ``zephyr`` repository. Among
other things, this script sources :file:`~/.zephyrrc`.
The value will be lost if you close the window, etc.; run ``source
zephyr-env.sh`` again to get it back.
.. group-tab:: Windows
Add the line ``set MY_VARIABLE=foo`` to the file
:file:`%userprofile%\\zephyrrc.cmd` using a text editor such as Notepad to
save the value.
To get this value back into your current terminal environment, **you must
run** ``zephyr-env.cmd`` in a ``cmd.exe`` window after changing directory
to the main ``zephyr`` repository. Among other things, this script runs
:file:`%userprofile%\\zephyrrc.cmd`.
The value will be lost if you close the window, etc.; run
``zephyr-env.cmd`` again to get it back.
These scripts:
- set :envvar:`ZEPHYR_BASE` (see below) to the location of the zephyr
repository
- adds some Zephyr-specific locations (such as zephyr's :file:`scripts`
directory) to your :envvar:`PATH` environment variable
- loads any settings from the ``zephyrrc`` files described above in
:ref:`env_vars_zephyrrc`.
You can thus use them any time you need any of these settings.
Option 4: Using Zephyr Build Configuration CMake package
=========================================================
Choose this option if you want to make those variable settings shared among all
users of your project.
Using a :ref:`cmake_build_config_package` allows you to commit the shared
settings into the repository, so that all users can share them.
It also removes the need for running ``source zephyr-env.sh`` or
``zephyr-env.cmd`` when opening a new terminal.
.. _important-build-vars: .. _important-build-vars:
@ -442,10 +304,21 @@ should know about.
See :ref:`set-devicetree-overlays` for examples and :ref:`devicetree-intro` See :ref:`set-devicetree-overlays` for examples and :ref:`devicetree-intro`
for information about devicetree and Zephyr. for information about devicetree and Zephyr.
* :makevar:`SHIELD`: see :ref:`shields`
* :makevar:`ZEPHYR_MODULES`: A CMake list containing absolute paths of * :makevar:`ZEPHYR_MODULES`: A CMake list containing absolute paths of
additional directories with source code, Kconfig, etc. that should be used in additional directories with source code, Kconfig, etc. that should be used in
the application build. See :ref:`modules` for details. the application build. See :ref:`modules` for details. If you set this
variable, it must be a complete list of all modules to use, as the build
system will not automatically pick up any modules from west.
* :makevar:`ZEPHYR_EXTRA_MODULES`: Like :makevar:`ZEPHYR_MODULES`, except these
will be added to the list of modules found via west, instead of replacing it.
.. note::
You can use a :ref:`cmake_build_config_package` to share common settings for
these variables.
Application CMakeLists.txt Application CMakeLists.txt
************************** **************************

195
doc/guides/env_vars.rst Normal file
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@ -0,0 +1,195 @@
.. _env_vars:
Environment Variables
=====================
Various pages in this documentation refer to setting Zephyr-specific
environment variables. This page describes how.
Setting Variables
*****************
Option 1: Just Once
-------------------
To set the environment variable :envvar:`MY_VARIABLE` to ``foo`` for the
lifetime of your current terminal window:
.. tabs::
.. group-tab:: Linux/macOS
.. code-block:: console
export MY_VARIABLE=foo
.. group-tab:: Windows
.. code-block:: console
set MY_VARIABLE=foo
.. warning::
This is best for experimentation. If you close your terminal window, use
another terminal window or tab, restart your computer, etc., this setting
will be lost forever.
Using options 2 or 3 is recommended if you want to keep using the setting.
Option 2: In all Terminals
--------------------------
.. tabs::
.. group-tab:: Linux/macOS
Add the ``export MY_VARIABLE=foo`` line to your shell's startup script in
your home directory. For Bash, this is usually :file:`~/.bashrc` on Linux
or :file:`~/.bash_profile` on macOS. Changes in these startup scripts
don't affect shell instances already started; try opening a new terminal
window to get the new settings.
.. group-tab:: Windows
You can use the ``setx`` program in ``cmd.exe`` or the third-party RapidEE
program.
To use ``setx``, type this command, then close the terminal window. Any
new ``cmd.exe`` windows will have :envvar:`MY_VARIABLE` set to ``foo``.
.. code-block:: console
setx MY_VARIABLE foo
To install RapidEE, a freeware graphical environment variable editor,
`using Chocolatey`_ in an Administrator command prompt:
.. code-block:: console
choco install rapidee
You can then run ``rapidee`` from your terminal to launch the program and set
environment variables. Make sure to use the "User" environment variables area
-- otherwise, you have to run RapidEE as administrator. Also make sure to save
your changes by clicking the Save button at top left before exiting.Settings
you make in RapidEE will be available whenever you open a new terminal window.
.. _env_vars_zephyrrc:
Option 3: Using ``zephyrrc`` files
----------------------------------
Choose this option if you don't want to make the variable's setting available
to all of your terminals, but still want to save the value for loading into
your environment when you are using Zephyr.
.. tabs::
.. group-tab:: Linux/macOS
Create a file named :file:`~/.zephyrrc` if it doesn't exist, then add this
line to it:
.. code-block:: console
export MY_VARIABLE=foo
To get this value back into your current terminal environment, **you must
run** ``source zephyr-env.sh`` from the main ``zephyr`` repository. Among
other things, this script sources :file:`~/.zephyrrc`.
The value will be lost if you close the window, etc.; run ``source
zephyr-env.sh`` again to get it back.
.. group-tab:: Windows
Add the line ``set MY_VARIABLE=foo`` to the file
:file:`%userprofile%\\zephyrrc.cmd` using a text editor such as Notepad to
save the value.
To get this value back into your current terminal environment, **you must
run** ``zephyr-env.cmd`` in a ``cmd.exe`` window after changing directory
to the main ``zephyr`` repository. Among other things, this script runs
:file:`%userprofile%\\zephyrrc.cmd`.
The value will be lost if you close the window, etc.; run
``zephyr-env.cmd`` again to get it back.
These scripts:
- set :envvar:`ZEPHYR_BASE` (see below) to the location of the zephyr
repository
- adds some Zephyr-specific locations (such as zephyr's :file:`scripts`
directory) to your :envvar:`PATH` environment variable
- loads any settings from the ``zephyrrc`` files described above in
:ref:`env_vars_zephyrrc`.
You can thus use them any time you need any of these settings.
.. _zephyr-env:
Zephyr Environment Scripts
**************************
You can use the zephyr repository scripts ``zephyr-env.sh`` (for macOS and
Linux) and ``zephyr-env.cmd`` (for Windows) to load Zephyr-specific settings
into your current terminal's environment. To do so, run this command from the
zephyr repository:
.. tabs::
.. group-tab:: Linux/macOS
.. code-block:: console
source zephyr-env.sh
.. group-tab:: Windows
.. code-block:: console
zephyr-env.cmd
These scripts:
- set :envvar:`ZEPHYR_BASE` (see below) to the location of the zephyr
repository
- adds some Zephyr-specific locations (such as zephyr's :file:`scripts`
directory) to your :envvar:`PATH` environment variable
- loads any settings from the ``zephyrrc`` files described above in
:ref:`env_vars_zephyrrc`.
You can thus use them any time you need any of these settings.
.. _env_vars_important:
Important Environment Variables
*******************************
Some :ref:`important-build-vars` can also be set in the environment. Here
is a description of some of these important environment variables. This is not
a comprehensive list.
- :envvar:`BOARD`
- :envvar:`CONF_FILE`
- :envvar:`SHIELD`
- :envvar:`ZEPHYR_BASE`
- :envvar:`ZEPHYR_EXTRA_MODULES`
- :envvar:`ZEPHYR_MODULES`
The following additional environment variables are significant when configuring
the :ref:`toolchain <gs_toolchain>` used to build Zephyr applications.
- :envvar:`ZEPHYR_TOOLCHAIN_VARIANT`: the name of the toolchain to use
- :envvar:`<TOOLCHAIN>_TOOLCHAIN_PATH`: path to the toolchain specified by
:envvar:`ZEPHYR_TOOLCHAIN_VARIANT`. For example, if
``ZEPHYR_TOOLCHAIN_VARIANT=llvm``, use :envvar:`LLVM_TOOLCHAIN_PATH`. (Note
the capitalization when forming the environment variable name.)
Emulators and boards may also depend on additional programs. The build system
will try to locate those programs automatically, but may rely on additional
CMake or environment variables to do so. Please consult your emulator's or
board's documentation for more information.
.. _using Chocolatey: https://chocolatey.org/packages/RapidEE

1
doc/guides/index.rst
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@ -17,6 +17,7 @@ User and Developer Guides
debug_tools/index debug_tools/index
device_mgmt/index device_mgmt/index
dts/index dts/index
env_vars.rst
pinctrl/index pinctrl/index
pm/index pm/index
emulator/index.rst emulator/index.rst

8
doc/guides/zephyr_cmake_package.rst
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@ -389,10 +389,10 @@ Zephyr Build Configuration CMake package
The Zephyr Build Configuration CMake package provides a possibility for a Zephyr based project to The Zephyr Build Configuration CMake package provides a possibility for a Zephyr based project to
control Zephyr build settings in a generic way. control Zephyr build settings in a generic way.
It is similar to the use of ``.zephyrrc`` but with the possibility to automatically allow all users It is similar to the per-user ``.zephyrrc`` file that can be used to set :ref:`env_vars`, but it
to share the build configuration through the project repository. sets CMake variables instead. It also allows you to automatically share the build configuration
But it also allows more advanced use cases than a ``.zephyrrc``-file, such as loading of additional among all users through the project repository. It also allows more advanced use cases, such as loading
CMake boilerplate code. of additional CMake boilerplate code.
The Zephyr Build Configuration CMake package will be loaded in the Zephyr boilerplate code after The Zephyr Build Configuration CMake package will be loaded in the Zephyr boilerplate code after
initial properties and ``ZEPHYR_BASE`` has been defined, but before CMake code execution. initial properties and ``ZEPHYR_BASE`` has been defined, but before CMake code execution.