ESP32: "user C modules" should be able to add components to the build #8041

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1. dpgeorge

   added

   port-esp32

   on Nov 29, 2021
2. mocleiri commented on Jan 15, 2022

   

   mocleiri

   on Jan 15, 2022

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   @aguaviva if you have control over the board directory then its possible with the current structure to include additional idf components in the build.

   This is the reference for the custom board config:
   https://github.com/micropython/micropython-example-boards/blob/main/boards/CUSTOM_ESP32

   There are two steps:

   1. Define the EXTRA_COMPONENT_DIRS variable to point at the directory containing the component. This makes additional idf components available to include in the build.
   2. Reference the extra components on the COMPONENTS variable. According to the documentation there are certain default components that build and then any REQUIRES components from the idf_component_register are also included.

   Its sort of a hack but the esp32 build only defines the components to build through the REQUIRES. That is where the IDF_COMPONENTS come in, So the COMPONENTS variable is available and when you set it that triggers building the additional components.

   I tried to set both via my user moduleś micropython.cmake file but it didn´t work. I was able to set the EXTRA_COMPONENT_DIRS in the board makefile:
   https://github.com/mocleiri/tensorflow-micropython-examples/blob/80a43ee1cf9ec24a7ebc0e1b7bb30ad5f461c01a/boards/esp32/MICROLITE/CMakeLists.txt#L6

   Then I set the components to build in the user module:
   https://github.com/mocleiri/tensorflow-micropython-examples/blob/80a43ee1cf9ec24a7ebc0e1b7bb30ad5f461c01a/micropython-modules/microlite/micropython.cmake#L52

   This process works, I can see the custom component build and the firmware links properly. For my project the firmware when flashed is buggy but I think that´s most likely unrelated to this approach.

   The downside is that it doesn´t work if you don´t control the board.

   👍React with 👍2Reacted by aguaviva and xlla
3. mortbauer commented on Sep 9, 2023

   

   mortbauer

   on Sep 9, 2023

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   Probably this should be solved with the switch to esp-idf v5, where list(APPEND IDF_COMPONENTS is used, however I still do not manage make this work, the result is different if I have user_c_module which appends a module or if I directly add it to the variable in esp32_common.cmake. The latter case works and the first produces errors when linking, I do not know what could be possibly be going on.
4. LnnrtS commented on Dec 18, 2023

   

   LnnrtS

   on Dec 18, 2023

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   This is (at least one of) the reason why it doesn't work

   micropython/ports/esp32/esp32_common.cmake

   Lines 14 to 17 in 3270d85

   	# CMAKE_BUILD_EARLY_EXPANSION is set during the component-discovery phase of
   	# `idf.py build`, so none of the extmod/usermod (and in reality, most of the
   	# micropython) rules need to happen. Specifically, you cannot invoke add_library.
   	if(NOT CMAKE_BUILD_EARLY_EXPANSION)

   Just always including generic usermod.cmake is not working since it calls add_library. Instead it would need some port-specific machinery to directly include the user module cmake file in the CMAKE_BUILD_EARLY_EXPANSION-phase. But then that flag needs to be checked there (to not call add_library). Plus you will probably need PARENT_SCOPE to write to the top level IDF_COMPONENTS variable.

   All in all, adding a port-specific make flag for additional components required my the c modules could be a cleaner compromise.