.. _west-build-flash-debug: Building, Flashing and Debugging ################################ Zephyr provides several :ref:`west extension commands ` for building, flashing, and interacting with Zephyr programs running on a board: ``build``, ``flash``, ``debug``, ``debugserver`` and ``attach``. For information on adding board support for the flashing and debugging commands, see :ref:`flash-and-debug-support` in the board porting guide. .. Add a per-page contents at the top of the page. This page is nested deeply enough that it doesn't have any subheadings in the main nav. .. only:: html .. contents:: :local: .. _west-building: Building: ``west build`` ************************ .. tip:: Run ``west build -h`` for a quick overview. The ``build`` command helps you build Zephyr applications from source. You can use :ref:`west config ` to configure its behavior. Its default behavior tries to "do what you mean": - If there is a Zephyr build directory named :file:`build` in your current working directory, it is incrementally re-compiled. The same is true if you run ``west build`` from a Zephyr build directory. - Otherwise, if you run ``west build`` from a Zephyr application's source directory and no build directory is found, a new one is created and the application is compiled in it. Basics ====== The easiest way to use ``west build`` is to go to an application's root directory (i.e. the folder containing the application's :file:`CMakeLists.txt`) and then run:: west build -b Where ```` is the name of the board you want to build for. This is exactly the same name you would supply to CMake if you were to invoke it with: ``cmake -DBOARD=``. .. tip:: You can use the :ref:`west boards ` command to list all supported boards. A build directory named :file:`build` will be created, and the application will be compiled there after ``west build`` runs CMake to create a build system in that directory. If ``west build`` finds an existing build directory, the application is incrementally re-compiled there without re-running CMake. You can force CMake to run again with ``--cmake``. You don't need to use the ``--board`` option if you've already got an existing build directory; ``west build`` can figure out the board from the CMake cache. For new builds, the ``--board`` option, :envvar:`BOARD` environment variable, or ``build.board`` configuration option are checked (in that order). .. _west-multi-domain-builds: Sysbuild (multi-domain builds) ============================== :ref:`sysbuild` can be used to create a multi-domain build system combining multiple images for a single or multiple boards. Use ``--sysbuild`` to select the :ref:`sysbuild` build infrastructure with ``west build`` to build multiple domains. More detailed information regarding the use of sysbuild can be found in the :ref:`sysbuild` guide. .. tip:: The ``build.sysbuild`` configuration option can be enabled to tell ``west build`` to default build using sysbuild. ``--no-sysbuild`` can be used to disable sysbuild for a specific build. ``west build`` will build all domains through the top-level build folder of the domains specified by sysbuild. A single domain from a multi-domain project can be built by using ``--domain`` argument. Examples ======== Here are some ``west build`` usage examples, grouped by area. Forcing CMake to Run Again -------------------------- To force a CMake re-run, use the ``--cmake`` (or ``-c``) option:: west build -c Setting a Default Board ----------------------- To configure ``west build`` to build for the ``reel_board`` by default:: west config build.board reel_board (You can use any other board supported by Zephyr here; it doesn't have to be ``reel_board``.) .. _west-building-dirs: Setting Source and Build Directories ------------------------------------ To set the application source directory explicitly, give its path as a positional argument:: west build -b path/to/source/directory To set the build directory explicitly, use ``--build-dir`` (or ``-d``):: west build -b --build-dir path/to/build/directory To change the default build directory from :file:`build`, use the ``build.dir-fmt`` configuration option. This lets you name build directories using format strings, like this:: west config build.dir-fmt "build/{board}/{app}" With the above, running ``west build -b reel_board samples/hello_world`` will use build directory :file:`build/reel_board/hello_world`. See :ref:`west-building-config` for more details on this option. Setting the Build System Target ------------------------------- To specify the build system target to run, use ``--target`` (or ``-t``). For example, on host platforms with QEMU, you can use the ``run`` target to build and run the :ref:`hello_world` sample for the emulated :ref:`qemu_x86 ` board in one command:: west build -b qemu_x86 -t run samples/hello_world As another example, to use ``-t`` to list all build system targets:: west build -t help As a final example, to use ``-t`` to run the ``pristine`` target, which deletes all the files in the build directory:: west build -t pristine .. _west-building-pristine: Pristine Builds --------------- A *pristine* build directory is essentially a new build directory. All byproducts from previous builds have been removed. To force ``west build`` make the build directory pristine before re-running CMake to generate a build system, use the ``--pristine=always`` (or ``-p=always``) option. Giving ``--pristine`` or ``-p`` without a value has the same effect as giving it the value ``always``. For example, these commands are equivalent:: west build -p -b reel_board samples/hello_world west build -p=always -b reel_board samples/hello_world By default, ``west build`` makes no attempt to detect if the build directory needs to be made pristine. This can lead to errors if you do something like try to reuse a build directory for a different ``--board``. Using ``--pristine=auto`` makes ``west build`` detect some of these situations and make the build directory pristine before trying the build. .. tip:: You can run ``west config build.pristine always`` to always do a pristine build, or ``west config build.pristine never`` to disable the heuristic. See the ``west build`` :ref:`west-building-config` for details. .. _west-building-verbose: Verbose Builds -------------- To print the CMake and compiler commands run by ``west build``, use the global west verbosity option, ``-v``:: west -v build -b reel_board samples/hello_world .. _west-building-generator: .. _west-building-cmake-args: One-Time CMake Arguments ------------------------ To pass additional arguments to the CMake invocation performed by ``west build``, pass them after a ``--`` at the end of the command line. .. important:: Passing additional CMake arguments like this forces ``west build`` to re-run the CMake build configuration step, even if a build system has already been generated. This will make incremental builds slower (but still much faster than building from scratch). After using ``--`` once to generate the build directory, use ``west build -d `` on subsequent runs to do incremental builds. Alternatively, make your CMake arguments permanent as described in the next section; it will not slow down incremental builds. For example, to use the Unix Makefiles CMake generator instead of Ninja (which ``west build`` uses by default), run:: west build -b reel_board -- -G'Unix Makefiles' To use Unix Makefiles and set `CMAKE_VERBOSE_MAKEFILE`_ to ``ON``:: west build -b reel_board -- -G'Unix Makefiles' -DCMAKE_VERBOSE_MAKEFILE=ON Notice how the ``--`` only appears once, even though multiple CMake arguments are given. All command-line arguments to ``west build`` after a ``--`` are passed to CMake. .. _west-building-dtc-overlay-file: To set :ref:`DTC_OVERLAY_FILE ` to :file:`enable-modem.overlay`, using that file as a :ref:`devicetree overlay `:: west build -b reel_board -- -DDTC_OVERLAY_FILE=enable-modem.overlay To merge the :file:`file.conf` Kconfig fragment into your build's :file:`.config`:: west build -- -DEXTRA_CONF_FILE=file.conf .. _west-building-cmake-config: Permanent CMake Arguments ------------------------- The previous section describes how to add CMake arguments for a single ``west build`` command. If you want to save CMake arguments for ``west build`` to use every time it generates a new build system instead, you should use the ``build.cmake-args`` configuration option. Whenever ``west build`` runs CMake to generate a build system, it splits this option's value according to shell rules and includes the results in the ``cmake`` command line. Remember that, by default, ``west build`` **tries to avoid generating a new build system if one is present** in your build directory. Therefore, you need to either delete any existing build directories or do a :ref:`pristine build ` after setting ``build.cmake-args`` to make sure it will take effect. For example, to always enable :makevar:`CMAKE_EXPORT_COMPILE_COMMANDS`, you can run:: west config build.cmake-args -- -DCMAKE_EXPORT_COMPILE_COMMANDS=ON (The extra ``--`` is used to force the rest of the command to be treated as a positional argument. Without it, :ref:`west config ` would treat the ``-DVAR=VAL`` syntax as a use of its ``-D`` option.) To enable :makevar:`CMAKE_VERBOSE_MAKEFILE`, so CMake always produces a verbose build system:: west config build.cmake-args -- -DCMAKE_VERBOSE_MAKEFILE=ON To save more than one argument in ``build.cmake-args``, use a single string whose value can be split into distinct arguments (``west build`` uses the Python function `shlex.split()`_ internally to split the value). .. _shlex.split(): https://docs.python.org/3/library/shlex.html#shlex.split For example, to enable both :makevar:`CMAKE_EXPORT_COMPILE_COMMANDS` and :makevar:`CMAKE_VERBOSE_MAKEFILE`:: west config build.cmake-args -- "-DCMAKE_EXPORT_COMPILE_COMMANDS=ON -DCMAKE_VERBOSE_MAKEFILE=ON" If you want to save your CMake arguments in a separate file instead, you can combine CMake's ``-C `` option with ``build.cmake-args``. For instance, another way to set the options used in the previous example is to create a file named :file:`~/my-cache.cmake` with the following contents: .. code-block:: cmake set(CMAKE_EXPORT_COMPILE_COMMANDS ON CACHE BOOL "") set(CMAKE_VERBOSE_MAKEFILE ON CACHE BOOL "") Then run:: west config build.cmake-args "-C ~/my-cache.cmake" See the `cmake(1) manual page`_ and the `set() command`_ documentation for more details. .. _cmake(1) manual page: https://cmake.org/cmake/help/latest/manual/cmake.1.html .. _set() command: https://cmake.org/cmake/help/latest/command/set.html Build tool arguments -------------------- Use ``-o`` to pass options to the underlying build tool. This works with both ``ninja`` (:ref:`the default `) and ``make`` based build systems. For example, to pass ``-dexplain`` to ``ninja``:: west build -o=-dexplain As another example, to pass ``--keep-going`` to ``make``:: west build -o=--keep-going Note that using ``-o=--foo`` instead of ``-o --foo`` is required to prevent ``--foo`` from being treated as a ``west build`` option. Build parallelism ----------------- By default, ``ninja`` uses all of your cores to build, while ``make`` uses only one. You can control this explicitly with the ``-j`` option supported by both tools. For example, to build with 4 cores:: west build -o=-j4 The ``-o`` option is described further in the previous section. Build a single domain --------------------- In a multi-domain build with :ref:`hello_world` and `MCUboot`_, you can use ``--domain hello_world`` to only build this domain:: west build --sysbuild --domain hello_world The ``--domain`` argument can be combined with the ``--target`` argument to build the specific target for the target, for example:: west build --sysbuild --domain hello_world --target help Use a snippet ------------- See :ref:`using-snippets`. .. _west-building-config: Configuration Options ===================== You can :ref:`configure ` ``west build`` using these options. .. NOTE: docs authors: keep this table sorted alphabetically .. list-table:: :widths: 10 30 :header-rows: 1 * - Option - Description * - ``build.board`` - String. If given, this the board used by :ref:`west build ` when ``--board`` is not given and ``BOARD`` is unset in the environment. * - ``build.board_warn`` - Boolean, default ``true``. If ``false``, disables warnings when ``west build`` can't figure out the target board. * - ``build.cmake-args`` - String. If present, the value will be split according to shell rules and passed to CMake whenever a new build system is generated. See :ref:`west-building-cmake-config`. * - ``build.dir-fmt`` - String, default ``build``. The build folder format string, used by west whenever it needs to create or locate a build folder. The currently available arguments are: - ``board``: The board name - ``source_dir``: The relative path from the current working directory to the source directory. If the current working directory is inside the source directory this will be set to an empty string. - ``app``: The name of the source directory. * - ``build.generator`` - String, default ``Ninja``. The `CMake Generator`_ to use to create a build system. (To set a generator for a single build, see the :ref:`above example `) * - ``build.guess-dir`` - String, instructs west whether to try to guess what build folder to use when ``build.dir-fmt`` is in use and not enough information is available to resolve the build folder name. Can take these values: - ``never`` (default): Never try to guess, bail out instead and require the user to provide a build folder with ``-d``. - ``runners``: Try to guess the folder when using any of the 'runner' commands. These are typically all commands that invoke an external tool, such as ``flash`` and ``debug``. * - ``build.pristine`` - String. Controls the way in which ``west build`` may clean the build folder before building. Can take the following values: - ``never`` (default): Never automatically make the build folder pristine. - ``auto``: ``west build`` will automatically make the build folder pristine before building, if a build system is present and the build would fail otherwise (e.g. the user has specified a different board or application from the one previously used to make the build directory). - ``always``: Always make the build folder pristine before building, if a build system is present. * - ``build.sysbuild`` - Boolean, default ``false``. If ``true``, build application using the sysbuild infrastructure. .. _west-flashing: Flashing: ``west flash`` ************************ .. tip:: Run ``west flash -h`` for additional help. Basics ====== From a Zephyr build directory, re-build the binary and flash it to your board:: west flash Without options, the behavior is the same as ``ninja flash`` (or ``make flash``, etc.). To specify the build directory, use ``--build-dir`` (or ``-d``):: west flash --build-dir path/to/build/directory If you don't specify the build directory, ``west flash`` searches for one in :file:`build`, then the current working directory. If you set the ``build.dir-fmt`` configuration option (see :ref:`west-building-dirs`), ``west flash`` searches there instead of :file:`build`. Choosing a Runner ================= If your board's Zephyr integration supports flashing with multiple programs, you can specify which one to use using the ``--runner`` (or ``-r``) option. For example, if West flashes your board with ``nrfjprog`` by default, but it also supports JLink, you can override the default with:: west flash --runner jlink You can override the default flash runner at build time by using the ``BOARD_FLASH_RUNNER`` CMake variable, and the debug runner with ``BOARD_DEBUG_RUNNER``. For example:: # Set the default runner to "jlink", overriding the board's # usual default. west build [...] -- -DBOARD_FLASH_RUNNER=jlink See :ref:`west-building-cmake-args` and :ref:`west-building-cmake-config` for more information on setting CMake arguments. See :ref:`west-runner` below for more information on the ``runner`` library used by West. The list of runners which support flashing can be obtained with ``west flash -H``; if run from a build directory or with ``--build-dir``, this will print additional information on available runners for your board. Configuration Overrides ======================= The CMake cache contains default values West uses while flashing, such as where the board directory is on the file system, the path to the zephyr binaries to flash in several formats, and more. You can override any of this configuration at runtime with additional options. For example, to override the HEX file containing the Zephyr image to flash (assuming your runner expects a HEX file), but keep other flash configuration at default values:: west flash --hex-file path/to/some/other.hex The ``west flash -h`` output includes a complete list of overrides supported by all runners. Runner-Specific Overrides ========================= Each runner may support additional options related to flashing. For example, some runners support an ``--erase`` flag, which mass-erases the flash storage on your board before flashing the Zephyr image. To view all of the available options for the runners your board supports, as well as their usage information, use ``--context`` (or ``-H``):: west flash --context .. important:: Note the capital H in the short option name. This re-runs the build in order to ensure the information displayed is up to date! When running West outside of a build directory, ``west flash -H`` just prints a list of runners. You can use ``west flash -H -r `` to print usage information for options supported by that runner. For example, to print usage information about the ``jlink`` runner:: west flash -H -r jlink .. _west-multi-domain-flashing: Multi-domain flashing ===================== When a :ref:`west-multi-domain-builds` folder is detected, then ``west flash`` will flash all domains in the order defined by sysbuild. It is possible to flash the image from a single domain in a multi-domain project by using ``--domain``. For example, in a multi-domain build with :ref:`hello_world` and `MCUboot`_, you can use the ``--domain hello_world`` domain to only flash only the image from this domain:: west flash --domain hello_world .. _west-debugging: Debugging: ``west debug``, ``west debugserver`` *********************************************** .. tip:: Run ``west debug -h`` or ``west debugserver -h`` for additional help. Basics ====== From a Zephyr build directory, to attach a debugger to your board and open up a debug console (e.g. a GDB session):: west debug To attach a debugger to your board and open up a local network port you can connect a debugger to (e.g. an IDE debugger):: west debugserver Without options, the behavior is the same as ``ninja debug`` and ``ninja debugserver`` (or ``make debug``, etc.). To specify the build directory, use ``--build-dir`` (or ``-d``):: west debug --build-dir path/to/build/directory west debugserver --build-dir path/to/build/directory If you don't specify the build directory, these commands search for one in :file:`build`, then the current working directory. If you set the ``build.dir-fmt`` configuration option (see :ref:`west-building-dirs`), ``west debug`` searches there instead of :file:`build`. Choosing a Runner ================= If your board's Zephyr integration supports debugging with multiple programs, you can specify which one to use using the ``--runner`` (or ``-r``) option. For example, if West debugs your board with ``pyocd-gdbserver`` by default, but it also supports JLink, you can override the default with:: west debug --runner jlink west debugserver --runner jlink See :ref:`west-runner` below for more information on the ``runner`` library used by West. The list of runners which support debugging can be obtained with ``west debug -H``; if run from a build directory or with ``--build-dir``, this will print additional information on available runners for your board. Configuration Overrides ======================= The CMake cache contains default values West uses for debugging, such as where the board directory is on the file system, the path to the zephyr binaries containing symbol tables, and more. You can override any of this configuration at runtime with additional options. For example, to override the ELF file containing the Zephyr binary and symbol tables (assuming your runner expects an ELF file), but keep other debug configuration at default values:: west debug --elf-file path/to/some/other.elf west debugserver --elf-file path/to/some/other.elf The ``west debug -h`` output includes a complete list of overrides supported by all runners. Runner-Specific Overrides ========================= Each runner may support additional options related to debugging. For example, some runners support flags which allow you to set the network ports used by debug servers. To view all of the available options for the runners your board supports, as well as their usage information, use ``--context`` (or ``-H``):: west debug --context (The command ``west debugserver --context`` will print the same output.) .. important:: Note the capital H in the short option name. This re-runs the build in order to ensure the information displayed is up to date! When running West outside of a build directory, ``west debug -H`` just prints a list of runners. You can use ``west debug -H -r `` to print usage information for options supported by that runner. For example, to print usage information about the ``jlink`` runner:: west debug -H -r jlink .. _west-multi-domain-debugging: Multi-domain debugging ====================== ``west debug`` can only debug a single domain at a time. When a :ref:`west-multi-domain-builds` folder is detected, ``west debug`` will debug the ``default`` domain specified by sysbuild. The default domain will be the application given as the source directory. See the following example:: west build --sysbuild path/to/source/directory For example, when building ``hello_world`` with `MCUboot`_ using sysbuild, ``hello_world`` becomes the default domain:: west build --sysbuild samples/hello_world So to debug ``hello_world`` you can do:: west debug or:: west debug --domain hello_world If you wish to debug MCUboot, you must explicitly specify MCUboot as the domain to debug:: west debug --domain mcuboot .. _west-runner: Flash and debug runners *********************** The flash and debug commands use Python wrappers around various :ref:`flash-debug-host-tools`. These wrappers are all defined in a Python library at :zephyr_file:`scripts/west_commands/runners`. Each wrapper is called a *runner*. Runners can flash and/or debug Zephyr programs. The central abstraction within this library is ``ZephyrBinaryRunner``, an abstract class which represents runners. The set of available runners is determined by the imported subclasses of ``ZephyrBinaryRunner``. ``ZephyrBinaryRunner`` is available in the ``runners.core`` module; individual runner implementations are in other submodules, such as ``runners.nrfjprog``, ``runners.openocd``, etc. Hacking ******* This section documents the ``runners.core`` module used by the flash and debug commands. This is the core abstraction used to implement support for these features. .. warning:: These APIs are provided for reference, but they are more "shared code" used to implement multiple extension commands than a stable API. Developers can add support for new ways to flash and debug Zephyr programs by implementing additional runners. To get this support into upstream Zephyr, the runner should be added into a new or existing ``runners`` module, and imported from :file:`runners/__init__.py`. .. note:: The test cases in :zephyr_file:`scripts/west_commands/tests` add unit test coverage for the runners package and individual runner classes. Please try to add tests when adding new runners. Note that if your changes break existing test cases, CI testing on upstream pull requests will fail. .. automodule:: runners.core :members: Doing it By Hand **************** If you prefer not to use West to flash or debug your board, simply inspect the build directory for the binaries output by the build system. These will be named something like ``zephyr/zephyr.elf``, ``zephyr/zephyr.hex``, etc., depending on your board's build system integration. These binaries may be flashed to a board using alternative tools of your choice, or used for debugging as needed, e.g. as a source of symbol tables. By default, these West commands rebuild binaries before flashing and debugging. This can of course also be accomplished using the usual targets provided by Zephyr's build system (in fact, that's how these commands do it). .. _cmake(1): https://cmake.org/cmake/help/latest/manual/cmake.1.html .. _CMAKE_VERBOSE_MAKEFILE: https://cmake.org/cmake/help/latest/variable/CMAKE_VERBOSE_MAKEFILE.html .. _CMake Generator: https://cmake.org/cmake/help/latest/manual/cmake-generators.7.html .. _MCUboot: https://mcuboot.com/