Sming build system ================== .. highlight:: text Introduction ------------ This guide is provided to assist with understanding, developing and modifying the build system. A Sming project is built from a set of static libraries (object archives). Typically the application code is one library, built from the user’s source code, whilst the other libraries are common to all projects and stored in a separate, shared location. Until recently Sming itself has always been built as one large library, but this is now broken into a number of discrete Component libraries. The concept is borrowed from Espressif’s ESP-IDF build system and whilst there are some similarities the two systems are completely independent. Building applications --------------------- Setup ~~~~~ These are the main variables you need to be aware of: .. envvar:: SMING_HOME must be set to the full path of the ``Sming`` directory. .. envvar:: SMING_ARCH Defines the target architecture - **Esp8266** The default if not specified. :envvar:`ESP_HOME` must also be provided to locate SDK & tools. - **Esp32** Supports ESP32 architecture. - **Host** builds a version of the library for native host debugging on Linux or Windows - **Rp2040** Supports Raspberry Pi RP2040-based boards. .. envvar:: SMING_SOC Some architectures support families of SOCs with different capabilities. Set this value to the specific variant being targeted. Will automatically set SMING_ARCH to the appropriate value. .. envvar:: SMING_CPP_STD The build standard applied for the framework. This defaults to C++17 if the toolchain supports it (GCC 5+), C++11 otherwise. You can override to use other standards, such as ``c++2a`` for experimental C++20 support. These variables are available for application use: .. envvar:: PROJECT_DIR Path to the project’s root source directory, without trailing path separator. This variable is available within makefiles, but is also provided as a #defined C string to allow references to source files within application code, such as with the ``IMPORT_FSTR`` macro. :envvar:`COMPONENT_PATH` As for PROJECT_DIR, but provides the path to the current component's root source directory. Converting existing projects ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Instead of ``Makefile-user.mk`` a project should provide a ``component.mk``. To convert to the new style: 1. Copy ``Makefile`` and ``component.mk`` from the ``Basic_Blink`` sample project 2. Copy any customisations from ``Makefile-user.mk`` into ``component.mk`` file. (Or, rename ``Makefile-user.mk`` to ``component.mk`` then edit it.) 3. Delete ``Makefile-user.mk`` 4. If the project uses any Arduino libraries, set the :envvar:`ARDUINO_LIBRARIES` variable **Targets** You can add your own targets to component.mk as usual. It’s a good idea to add a comment for the target, like this:: ##@Building .PHONY: mytarget mytarget: ##This is my target When you type ``make help`` it will appear in the list. If you need a target to be added as a dependency to the main application build, add it to ``CUSTOM_TARGETS`` - the :sample:`Basic_Serial` sample contains a simple example of this. .. envvar:: ARDUINO_LIBRARIES If your project uses any Arduino libraries, you must set this value appropriately. **Source files** Use :envvar:`COMPONENT_SRCDIRS` instead of ``MODULES``. Use :envvar:`COMPONENT_SRCFILES` to add individual files. **Include paths** Use :envvar:`COMPONENT_INCDIRS` instead of :envvar:`EXTRA_INCDIR`, unless the paths are only required to build this Component. See `component.mk <#component-configuration>`__ for a full list of variables. Building ~~~~~~~~ You should normally work from the project directory. Examples: - Type ``make`` to build the project and any required Components. To speed things up, use parallel building, e.g. ``make -j5`` will build using a maximum of 5 concurrent jobs. The optimum value for this is usually (CPU CORES + 1). Using ``make -j`` will use unlimited jobs, but can cause problems in virtual environments. - Type ``make help`` from the project directory to get a list of available build targets. To switch to a different build architecture, for example: - Type ``make SMING_ARCH=Host`` to build the project for the host emulator - Type ``make flash`` to copy any SPIFFS image (if enabled) to the virtual flash, and run the application. (Note that you don’t need to set SMING_ARCH again, the value is cached.) To inspect the current build configuration, type ``make list-config``. Hardware configuration ~~~~~~~~~~~~~~~~~~~~~~ The appropriate hardware configuration should be selected in the project's component.mk file. Use one of the standard configurations or create your own. See :ref:`hardware_config`. Configuration variables ~~~~~~~~~~~~~~~~~~~~~~~ Configuration variables should be set in the project’s component.mk file. If appropriate, they can also be set as environment variables. During development, the easiest way to change variables is on the ``make`` command line. These are cached so persist between make sessions, and will override any values set in your project’s ``component.mk`` file. For example: - Type ``make SPIFF_BIN=test-rom`` to build the project and (if enabled) create a SPIFFS image file called ``test-rom.bin`` - Type ``make flash COM_PORT=COM4`` to flash the project and ``test-rom`` SPIFFS image using the provided flash memory settings - Next time you type ``make flash``, the same settings will be used, no need to type them again A separate cache is maintained for each build type (arch + release/debug). For example: - Type ``make SMING_RELEASE=1 list-config`` to switch to release build and display the active configuration Type ``make config-clean`` to clear all caches and revert to defaults. For reference, a copy of all build variables are stored in a file with each firmware image created in the ‘firmware’ directory. Component repositories ~~~~~~~~~~~~~~~~~~~~~~ Placing Components in a common location allows them to be used by multiple projects. To set up your own Component repository, create a directory in a suitable location which will contain your Components and set ``COMPONENT_SEARCH_DIRS`` to the full path of that directory. For example:: |_ opt/ |_ shared/ |_ Components/ The repository |_ MyComponent/ |_ AnotherComponent/ |_ spiffs/ Will be used instead of Sming version User repositories are searched first, which allows replacement of any Component for a project. In this example, our ``spiffs`` component will be selected instead of the one provided with Sming. Directory layout ---------------- The main Sming repo. is laid out like this:: |_ sming/ |_ .appveyor.yml CI testing |_ .travis.yml CI testing |_ .readthedocs.yml Documentation build |_ lgtm.yml CI Static code analysis |_ docs/ Sming documentation |_ samples/ Samples to demonstrate specific Sming features or libraries |_ Sming/ | |_ Makefile Builds documentation, performs global actions on the framework | |_ project.mk Main makefile to build a project | |_ build.mk Defines the build environment | |_ component.mk Sming Component definition file | |_ component-wrapper.mk Used to build each Component using a separate make instance | |_ Arch/ Architecture-specific makefiles and code | | |_ Esp8266/ | | | |_ sming.mk Defines architecture-specific Components and libraries | | | |_ app.mk Link the project, create output binaries | | | | and perform architecture-specific actions | | | |_ build.mk Architecture-specific build definitions, such as compiler paths | | | |_ Compiler/ | | | |_ Components/ | | | |_ Core/ | | | |_ Platform/ | | | |_ System/ | | | |_ Tools/ Pre-compiled or scripted tools | | |_ Esp32/ | | | |_ ... | | |_ Host/ | | |_ ... | |_ Components/ Framework support code, not to be used directly by applications | |_ Core/ Main framework core | |_ Libraries/ Arduino Libraries | | |_ ... | |_ out/ All generated shared files are written here | | |_ Esp8266/ The Arch | | | |_ debug/ The build type | | | |_ build/ Intermediate object files | | | | |_ Lib/ Generated libraries | | | | |_ tools/ Generated tools | | | |_ release/ | | | |_ ... | | |_ Host/ | | |_ ... | |_ Platform/ System-level classes | | |_ ... | |_ Services/ Modules not considered as part of Core | | |_ ... | |_ System/ Common framework low-level system code | | |_ include/ | |_ Wiring/ | |_ ... |_ tests/ Integration test applications |_ ... |_ Tools/ |_ ci CI testing |_ Docker |_ ide IDE environment support tools |_ Python Shared python scripts |_ travis CI testing A typical Project looks like this:: |_ Basic_Blink/ |_ Makefile Just includes project.mk |_ component.mk Project-specific definitions |_ app/ Default application source directory |_ include/ Default application include directory |_ out/ All generated shared files are written here |_ Esp8266/ The Architecture | |_ debug/ The build type | | |_ build/ Intermediate object files | | |_ firmware/ Target output files | | |_ lib/ Generated libraries | | |_ tools/ Generated tools | |_ release/ | |_ ... |_ Host |_ ... .. _component: Component --------- The purpose of a Component is to encapsulate related elements for selective inclusion in a project, for easy sharing and re-use: - **Shared Library** with associated header files - **App Code** Source files to be compiled directly into the user’s project - **Header files** without any associated source or library - **Build targets** to perform specific actions, such as flashing binary data to hardware By default, a Component is built into a shared library using any source files found in the base or ``src`` directories. All Arduino Libraries are built as Components. Note that the application is also built as a Component library, but the source directory defaults to ``app`` instead of ``src``. Components are referred to simply by name, defined by the directory in which it is stored. The Component itself is located by looking in all the directories listed by ``COMPONENT_SEARCH_DIRS``, which contains a list of repositories. (Every sub-directory of a repository is considered to be a Component.) If there are Components with the same name in different search directories, the first one found will be used. Components are customised by providing an optional ``component.mk`` file. You can see details of all Components used in a project using ``make list-components``. Add ``V=1`` to get more details. Note that the application itself is also built as a Component, and may be configured in a similar way to any other Component. Library variants ~~~~~~~~~~~~~~~~ Libraries can often be built using different option settings, so a mechanism is required to ensure that libraries (including the application) are rebuilt if those settings change. This is handled using *variants*, which modifies the library name using a hash of the settings values. Each variant gets its own build sub-directory so incremental building works as usual. There are several types of config variable: +-------------+-------------+-------------+-------------+-------------+ | Variable | Cached? | Rebuild | Rebuild | Relink | | type | | Component? | application | application | | | | | ? | | +=============+=============+=============+=============+=============+ | COMPONENT | Y | Y | Y | Y | +-------------+-------------+-------------+-------------+-------------+ | CONFIG | Y | N | Y | Y | +-------------+-------------+-------------+-------------+-------------+ | RELINK | Y | N | N | Y | +-------------+-------------+-------------+-------------+-------------+ | CACHE | Y | N | N | N | +-------------+-------------+-------------+-------------+-------------+ | DEBUG | N | N | N | N | +-------------+-------------+-------------+-------------+-------------+ Variables are usually defined in the context of a Component, in the component.mk file. All Components see the full configuration during building, not just their own variables. The type of a configuration variable is defined by adding its *name* to one of the following lists: .. envvar:: CONFIG_VARS The Application library derives its variant from these variables. Use this type if the Component doesn’t require a rebuild, but the application does. .. envvar:: COMPONENT_VARS A Component library derives its variant from these variables. Any variable which requires a rebuild of the Component library itself must be listed. For example, the ``esp-open-lwip`` Component defines this as ``ENABLE_LWIPDEBUG ENABLE_ESPCONN``. The default values for these produces ``ENABLE_LWIPDEBUG=0 ENABLE_ESPCONN=0``, which is hashed (using MD5) to produce ``a46d8c208ee44b1ee06f8e69cfa06773``, which is appended to the library name. All dependent Components (which list this one in :envvar:`COMPONENT_DEPENDS`) will also have a variant created. .. envvar:: COMPONENT_RELINK_VARS Behaves just like ``COMPONENT_VARS`` except dependent Components are not rebuilt. This is appropriate where the public interface (header files) are not affected by the variable setting, but the library implementation still requires a variant. .. envvar:: RELINK_VARS Code isn’t re-compiled, but libraries are re-linked and firmware images re-generated if any of these variables are changed. For example, ``make RBOOT_ROM_0=new-rom-file`` rewrites the firmware image using the given filename. (Also, as the value is cached, if you then do ``make flashapp`` that same image gets flashed.) .. envvar:: CACHE_VARS These variables have no effect on building, but are cached. Variables such as ``COM_SPEED_ESPTOOL`` fall into this category. .. envvar:: DEBUG_VARS These are generally for information only, and are not cached (except for :envvar:`SMING_ARCH` and :envvar:`SMING_RELEASE`). Note that the lists not prefixed ``COMPONENT_xx`` are global and so should only be appended, never assigned. Dependencies ~~~~~~~~~~~~ :envvar:`COMPONENT_DEPENDS` identifies a list of Components upon which this one depends. These are established as pre-requisites so will trigger a rebuild. In addition, all dependent :envvar:`COMPONENT_VARS` are (recursively) used in creation of the library hash. For example, the ``axtls-8266`` Component declares :envvar:`SSL_DEBUG` as a ``COMPONENT_VAR``. Because ``Sming`` depends on ``sming-arch``, which in turn depends on ``axtls-8266``, all of these Components get rebuilt as different variants when ``SSL_DEBUG`` changes values. The project code (``App`` Component) also gets rebuilt as it implicitly depends on ``Sming``. .. _git_submodules: GIT Submodules ~~~~~~~~~~~~~~ Sming uses source code from other repositories. Instead of including local copies, these are handled using GIT submodules. Where changes are required, patches may be provided as a diff .patch file and/or set of files to be added/replaced. Only those submodules necessary for a build are pulled in, as follows: - The submodule is fetched from its remote repository - If a .patch file exists, it is applied - Any additional files are copied into the submodule directory - An empty ``.submodule`` file is created to tells the build system that the submodule is present and correct. The patch file must have the same name as the submodule, with a .patch extension. It can be located in the submodule’s parent directory:: |_ Components/ |_ heap/ |_ .component.mk Component definition |_ umm_malloc.patch Diff patch file |_ umm_malloc/ Submodule directory |_ .submodule Created after successful patching ... However, if the Component is itself a submodule, then patch files must be placed in a ``../.patches`` directory:: |_ Libraries/ |_ .patches/ | |_ Adafruit_SSD1306.patch Diff patch file | |_ Adafruit_SSD1306/ | |_ component.mk This file is added to submodule |_ Adafruit_SSD1306/ The submodule directory |_ .submodule Created after successful patching ... This example includes additional files for the submodule. There are some advantages to this approach: 1. Don’t need to modify or create .patch 2. Changes to the file are easier to follow than in a .patch 3. **IMPORTANT** Adding a component.mk file in this manner allows the build system to resolve dependencies before any submodules are fetched. In the above example, the ``component.mk`` file defines a dependency on the ``Adafruit_GFX`` library, so that will automatically get pulled in as well. Component configuration ~~~~~~~~~~~~~~~~~~~~~~~ The ``component.mk`` is parsed twice, first from the top-level makefile and the second time from the sub-make which does the actual building. A number of variables are used to define behaviour. These values are for reference only and should not be modified. .. envvar:: COMPONENT_NAME Name of the Component .. envvar:: COMPONENT_PATH Base directory path for Component, no trailing path separator .. envvar:: COMPONENT_BUILD_DIR The current directory. This should be used if the Component provides any application code or targets to ensure it is built in the correct directory (but not by this makefile). This value changes depending on the build variant. .. envvar:: COMPONENT_BUILD_BASE This value does not change with build variant. If the Component generates source code, for example, it can be placed here (in a sub-directory). .. envvar:: COMPONENT_LIBDIR Location to store created Component (shared) libraries .. envvar:: COMPONENT_VARIANT Name of the library to build .. envvar:: COMPONENT_LIBPATH Full path to the library to be built These values may be used to customise Component behaviour and may be changed as required. .. envvar:: COMPONENT_LIBNAME By default, the library has the same name as the Component but can be changed if required. Note that this will be used as the stem for any variants. Set ``COMPONENT_LIBNAME :=`` if the Component doesn’t create a library. If you don’t do this, a default library will be built but will be empty if no source files are found. .. envvar:: COMPONENT_TARGETS Set this to any additional targets to be built as part of the Component, prefixed with ``$(COMPONENT_RULE)``. If targets should be built for each application, use :envvar:`CUSTOM_TARGETS` instead. See :library:`Spiffs` for an example. .. envvar:: COMPONENT_PREREQUISITES These targets will be built before anything else. If your library generates source code, for example, then it should be done by setting this value to the appropriate targets. .. envvar:: COMPONENT_RULE This is a special value used to prefix any custom targets which are to be built as part of the Component. The target must be prefixed by ``$(COMPONENT_RULE)`` without any space between it and the target. This ensures the rule only gets invoked during a component build, and is ignored by the top-level make. .. envvar:: COMPONENT_SUBMODULES Relative paths to dependent submodule directories for this Component. These will be fetched/patched automatically before building. Default behaviour is to initialise submodules recursively. To prevent this behaviour and initialise only the top-level submodule, add a file to the parent directory with the same name as the submodule and a ``.no-recursive`` extension. .. envvar:: COMPONENT_SRCDIRS Locations for source code relative to COMPONENT_PATH (defaults to “. src”) .. envvar:: COMPONENT_SRCFILES Individual source files. Useful for conditional includes. .. envvar:: COMPONENT_INCDIRS Default: "include". Include directories available when building ALL Components (not just this one). Paths may be relative or absolute .. envvar:: EXTRA_INCDIR Include directories for just this Component. Paths may be relative or absolute .. envvar:: INCDIR The resultant set of include directories used to build this Component. Will contain include directories specified by all other Components in the build. May be overridden if required. .. envvar:: COMPONENT_APPCODE List of directories containing source code to be compiled directly with the application. (Ignore in the project.mk file - use :envvar:`COMPONENT_SRCDIRS` instead). .. envvar:: CUSTOM_BUILD Set to 1 if providing an alternative build method. See `Custom building <#custom-building>`__ section. .. envvar:: EXTRA_OBJ Absolute paths to any additional binary object files to be added to the Component archive library. .. envvar:: COMPONENT_DEPENDS Set to the name(s) of any dependent Components. .. envvar:: EXTRA_LIBS Set to names of any additional libraries to be linked. .. envvar:: EXTRA_LDFLAGS Set to any additional flags to be used when linking. .. envvar:: COMPONENT_PYTHON_REQUIREMENTS If the component requires uncommon Python modules (e. g. as part of a custom build step), set this variable to one or more `requirements.txt `_ files. This allows installation of all python requirements of the project by invoking:: make python-requirements [PIP_ARGS=...] .. note:: A `requirements.txt` file in the root directory of the Component is detected automatically without setting this variable. To prevent autodetection (e.g. if the python requirements depend on another configuration variable) you must set this variable to an empty value. .. envvar:: PIP_ARGS See :envvar:`COMPONENT_PYTHON_REQUIREMENTS`. These values are global so must only be appended to (with ``+=``) , never overwritten. .. envvar:: CUSTOM_TARGETS Identifies targets to be built along with the application. These will be invoked directly by the top-level make. .. envvar:: GLOBAL_CFLAGS Use only if you need to provide additional compiler flags to be included when building all Components (including Application) and custom targets. .. envvar:: APP_CFLAGS Used when building application and custom targets. .. envvar:: COMPONENT_CFLAGS Will be visible **ONLY** to C code within the component. .. envvar:: COMPONENT_CXXFLAGS Will be visible **ONLY** to C++ code within the component. .. envvar:: COMPONENT_CPPFLAGS Will be visible to both C and C++ code within the component. .. important:: During initial parsing, many of these variables (specifically, the ``COMPONENT_xxx`` ones) *do not* keep their values. For this reason it is usually best to use simple variable assignment using ``:=``. For example, in ``Esp8266/Components/gdbstub`` we define ``GDB_CMDLINE``. It may be tempting to do this:: GDB_CMDLINE = trap '' INT; $(GDB) -x $(COMPONENT_PATH)/gdbcmds -b $(COM_SPEED_GDB) -ex "target remote $(COM_PORT_GDB)" That won’t work! By the time ``GDB_CMDLINE`` gets expanded, ``COMPONENT_PATH`` could contain anything. We need ``GDB_CMDLINE`` to be expanded only when used, so the solution is to take a simple copy of ``COMPONENT_PATH`` and use it instead, like this:: GDBSTUB_DIR := $(COMPONENT_PATH) GDB_CMDLINE = trap '' INT; $(GDB) -x $(GDBSTUB_DIR)/gdbcmds -b $(COM_SPEED_GDB) -ex "target remote $(COM_PORT_GDB)" These values are global and should be used ONLY in the ``Sming/Arch/*/build.mk`` files to tune the architecture compilation flags. These values must only be appended to (with ``+=``), never overwritten. .. envvar:: CPPFLAGS Used to provide both C and C++ flags that are applied globally. .. envvar:: CFLAGS Used to provide **ONLY** C flags that are applied globally. .. envvar:: CXXFLAGS Used to provide **ONLY** C++ flags that are applied globally. .. envvar:: SMING_C_STD Used to provide the C language standard. The default is ``c11``. .. important:: Do **NOT** set ``CPPFLAGS``, ``CFLAGS`` and ``CXXFLAGS`` outside of the ``Sming/Arch/*/build.mk`` files. Building ~~~~~~~~ For faster builds use make with the ``-j`` (jobs) feature of make. It is usually necessary to specify a limit for the number of jobs, especially on virtual machines. There is usually no point in using a figure greater than (CPU cores + 1). The CI builds use ``-j3``. Note that ``Makefile-app.mk`` enforces sequential building to ensure submodules are fetched and patched correctly. This also ensures that only one Component is built at a time which keeps the build logs quite clean and easy to follow. Components can be rebuilt and cleaned individually. For example: - ``make spiffs-build`` runs the Component ‘make’ for spiffs, which contains the SPIFFS library. - ``make spiffs-clean`` removes all intermediate build files for the Component - ``make spiffs-rebuild`` cleans and then re-builds the Component By default, a regular ``make`` performs an incremental build on the application, which invokes a separate (recursive) make for the ``App`` Component. All other Components only get built if any of their targets don’t exist (e.g. variant library not yet built). This makes application building faster and less ‘busy’, which is generally preferable for regular application development. For Component development this behaviour can be changed using the ``FULL_COMPONENT_BUILD`` variable (which is cached). Examples: - ``make FULL_COMPONENT_BUILD=lwip`` will perform an incremental build on the ``lwip`` Component - ``make FULL_COMPONENT_BUILD=1`` will incrementally build all Components Custom Building ~~~~~~~~~~~~~~~ To use an external makefile or other build system (such as CMake) to create the Component library, or to add additional shared libraries or other targets, customise the ``component.mk`` file as follows: 1. Set ``CUSTOM_BUILD=1`` 2. Define the custom rule, prefixed with ``$(COMPONENT_RULE)``. Note that Components are built using a separate make instance with the current directory set to the build output directory, not the source directory. It is important that the rule uses the provided values for ``COMPONENT_LIBNAME``, ``COMPONENT_LIBPATH`` and ``COMPONENT_LIBDIR`` so that variant building, cleaning, etc. work correctly. See below under ‘Building’, and the Host ``lwip`` Component for an example. Components are built using a make instance with the current directory set to the build output directory, not the source directory. If any custom building is done then these variables must be obeyed to ensure variants, etc. work as expected: ``COMPONENT_LIBNAME`` as provided by component.mk, defaults to component name, e.g. \ ``Sming`` ``COMPONENT_LIBHASH`` hash of the component variables used to create unique library names, e.g. \ ``13cd2ddef79fda79dae1644a33bf48bb`` ``COMPONENT_VARIANT`` name of the library to be built, including hash. e.g. \ ``Sming-13cd2ddef79fda79dae1644a33bf48bb`` ``COMPONENT_LIBDIR`` directory where any generated libraries must be output, e.g. \ ``/home/user/sming/Sming/out/Esp8266/debug/lib/`` ``COMPONENT_LIBPATH`` full path to the library to be created, e.g. \ ``/home/user/sming/Sming/out/Esp8266/debug/lib/clib-Sming-13cd2ddef79fda79dae1644a33bf48bb.a`` ``COMPONENT_BUILDDIR`` where to write intermediate object files, e.g. \ ``/home/user/sming/Sming/out/Esp8266/debug/build/Sming/Sming-13cd2ddef79fda79dae1644a33bf48bb`` Porting existing libraries ~~~~~~~~~~~~~~~~~~~~~~~~~~ to be completed Known Issues ------------ **Cleaning** Components are not cleaned unless defined. e.g. \ ``make axtls-8266-clean`` will fail unless you also specify ``ENABLE_SSL=1``. **Empty libraries** Components without any source code produce an empty library. This is because, for simplicity, we don’t want to add a component.mk to every Arduino library. **Empty Component directories** Every sub-directory in the ``COMPONENT_SEARCH_DIRS`` is interpreted as a Component. For example, ``spiffs`` was moved out of Arch/Esp8266/Components but if an empty directory called ‘spiffs’ still remains then it will be picked up instead of the main one. These sorts of issues can be checked using ``make list-components`` to ensure the correct Component path has been selected.