CMake usage in recommended project structure

[jensboe]

If I read https://modm.io/guide/custom-project/ correct it is intended to maintain multiple binaries in one repo (in example a dual core processor)

.
├── ext
│   └── modm
│       ├── repo.lb
│      ...
└── app
    ├── nice_project_1
    │  ├── main.cpp
    │  └── project.xml
    └── nice_project_2
        ├── main.cpp
        └── project.xml

Therefor for each project lbuild must be run and each got an modm folder.

Is this the intended way for modm?

In this configuration I normally have a CMakeLists.txt which includes "everything" and can build everything in root/build/ (root/build/app/nice_project_1, root/build/app/nice_project_2 and so on). With only to commands I can build every target. No directory switching needed.

If I try to do it with an modm_project, I got some errors because the pathes doesn't match because wrong variables are used at some places.

I could fix it easily and can create an PR.

Maybe https://github.com/modm-ext/modm_starter_project should be updated to match the recommended file structure of https://modm.io/guide/custom-project/

[jensboe]

One problem while trying to fix/improve cmake: I need to update the path of the linkerscript in LINKFLAGS -Tmodm/link/linkerscript.ld should be -T${PROJECT_SOURCE_DIR}/modm/link/linkerscript.ld

But I am not a python or lbuild expert. \modm\tools\build_script_generator\scons\module.lb set linkerscript path in build(env) function but if I try to copy that into cmake, it fails. the build function in modm\src\modm\platform\core\cortex\module.lb always "wins" (and got called before cmake-build.

I then try to use the override option of cortex-m <option name="modm:platform:cortex-m:linkerscript.override">"${PROJECT_SOURCE_DIR}/modm/link/linkerscript.ld"</option> but if failes because lbuild wants to resolve the ${PROJECT_SOURCE_DIR} variable which doesn't exists because it's for CMake.

If I use a real relative path it works<option name="modm:platform:cortex-m:linkerscript.override">app/nice_project_1/modm/link/linkerscript.ld</option>.

[salkinium]

It's intended to compile the projects separately. I'm not a CMake expert, there's too much conflicting advice online about how to do things in CMake that I never got how it's supposed to work, so I don't really know how good our solution is. Thank you for improving it!

What you're looking for is this flag_format function, that translates placeholder values in collected flags into the build system specific format.

The linkerscript flags gets added here. You can see that the -L{project_source_dir} flag gets translated to -L${CMAKE_SOURCE_DIR} via the flag_format function for CMake.

So you should get this behavior by replacing CMAKE_SOURCE_DIR with PROJECT_SOURCE_DIR in the flag_format function and everything else should work as you intended?

[salkinium]

Did you find a solution to your problem?