mbed-tools doesn't parse custom_targets.json

Description

custom_targets.json is not read

mbed-tools: 3.5.0

Issue request type

• Enhancement
• Bug

[Patater]

Hi @jrobeson

Thanks for the bug report. I can confirm this is not implemented yet and that we'll want the ability in mbed-tools to use custom targets.

[boraozgen]

This is a dealbreaker for us.

[ladislas]

@Patater -- I'm willing to take a look at this. Are you guys already working on this? If not, can you tell me the kind of approach you'd like to see and where I should start?

[0Grit]

Need this fixed

[rwalton-arm]

We're working on this now. There was some delay due to the holidays, but we should have this feature merged in the next couple of weeks.

[ladislas]

I'll update the issues when the feature is merged. Should be within the next couple of weeks.

Couple, like one or two, or more like 4 or 6? ;)

if you need help, please let us know! We're eager to help :)

[rwalton-arm]

I'll update the issues when the feature is merged. Should be within the next couple of weeks.

Couple, like one or two, or more like 4 or 6? ;)

if you need help, please let us know! We're eager to help :)

I would say ~2 weeks. 4 or 6 weeks would be a "few weeks" and not a "couple" ;). Sorry you've had to wait a while for this feature. As I mentioned earlier, holidays have caused some delay in completing the work. The mbed-tools side of this is basically done, as you can see in #160

The remaining issues are:

• Finding a user friendly way to add the custom target's source code to mbed's CMake build system without breaking the build for standard targets.
• Ensuring the correct target directory is pulled into the build by CMake, based on the filtering rules defined in custom_targets.json.

After we come up with a solution for these workflow issues we'll get the mbed-tools support merged so you can try it out.

[ladislas]

Finding a user friendly way to add the custom target's source code to mbed's CMake build system without breaking the build for standard targets.

@rwalton-arm in our project (using USCRPL/mbed-cmake), we have our custom targets at the root of the project with a CMakeLists.txt files in each of those.

The directory structure:

targets/TARGET_LEKA_V1_0_DEV
├── CMakeLists.txt
├── PeripheralNames.h
├── PeripheralPins.c
├── PinNames.h
├── PinNames.orig
└── system_clock.c

The CMakeLists.txt: https://github.com/ladislas/mbed-cmake-template/blob/develop/targets/TARGET_DISCO_ORIGINAL/CMakeLists.txt#L5-L18

add_library(target_DISCO_ORIGINAL STATIC)

target_sources(target_DISCO_ORIGINAL
  PRIVATE
	PeripheralPins.c
	system_clock.c
)

target_include_directories(target_DISCO_ORIGINAL
  PUBLIC
    ${CMAKE_CURRENT_SOURCE_DIR}
)

target_link_libraries(target_DISCO_ORIGINAL mbed-os)

We use different build directories to build with our different targets. When the target is a custom target, we call our config scripts with -x NAME_OF_TARGET.

Then we have a simple function to parse the name and link the application code with the right target: https://github.com/ladislas/mbed-cmake-template/blob/develop/src/CMakeLists.txt

# in main CMakeLists.txt
target_link_custom_boards(my_app_target)

https://github.com/ladislas/mbed-cmake-template/blob/develop/cmake/utils/Utils.cmake#L135-L145

# and in utils.cmake
function (target_link_custom_boards TARGET)
	# List of custom targets we use
	set(AVAILABLE_TARGET_BOARDS DISCO_ORIGINAL LEKA_V1_0_DEV)
	if (${TARGET_BOARD} MATCHES "\-x")
		string(REPLACE "\-x " "" CUSTOM_BOARD ${TARGET_BOARD})
		foreach(board IN ITEMS ${AVAILABLE_TARGET_BOARDS})
			if (${CUSTOM_BOARD} MATCHES ${board})
				message(STATUS "Adding ${board} library dependency to ${TARGET}")
				target_link_libraries(${TARGET} target_${board})
			endif()
		endforeach()
	endif()
endfunction()

If you're not using a custom target, then you don't have the -x, then the function does nothing and it just uses the mbed target.

The full example is available here: https://github.com/ladislas/mbed-cmake-template

What do you mean by?

Ensuring the correct target directory is pulled into the build by CMake, based on the filtering rules defined in custom_targets.json.