[ros-users] [Discourse.ros.org] [Next Generation ROS] Error using python3 nodes on ARM64 & CoreDX

[Dirk Thomas]

[quote="BrannonKing, post:6, topic:3057"]
What is func set to there?
[/quote]

The struct containing `func` is being declared [here](https://github.com/ros2/rosidl/blob/34fdfe6b3b8b8de0c41afd079ae8f361747b3c4a/rosidl_generator_c/include/rosidl_generator_c/message_type_support_struct.h#L35).

For the CoreDX C typesupport it is initialized [here](https://github.com/asirobots/rmw_coredx/blob/5aad0cca594edfeee7e8967327ac7f0fc6348a56/rosidl_typesupport_coredx_c/resource/msg__type_support_c.cpp.em#L566).

The function basically provide the typesupport for a specific message which enables "generically" written code to use / interact with messages which were not available at compile time but which have been defined later.

[quote="BrannonKing, post:6, topic:3057"]
Or where would I put my next printf?
[/quote]

I would suggest to build in `Debug` so that the `assert`'s are being checked. Additionally printing the value of `handle` as well as its members and `identifier` might provide valuable information (within [message_type_support.c](https://github.com/ros2/rosidl/blob/48eb1bc0ee2902feaad47eb55c19c10a2c322410/rosidl_generator_c/src/message_type_support.c#L21-L29)).

[quote="dirk-thomas, post:7, topic:3057"]
a set of copy-n-paste-able steps
[/quote]

I was expecting a list of command line invocations which I can easily run by copy-and-pasting them to a console. I managed to follow your text instructions (even though bullet 7 and 8 are in the wrong order). In the future it would be great to provide ready-to-run commands (e.g. instead of letting people edit files it is more convenient to share the already edited version through Gist) since it reduces the effort to help you and makes the whole process less ambiguous.

Anyway my build finished and when I run the talker and listener I see the following error message twice:

```
dds_thread_set_stacksize(): pthread_attr_setstacksize() error(22):Invalid argument
```

Beside that the talker is printing `Publishing: "Hello World: N"` and the listener `I heard: [Hello World: N]` so that seems to work just fine for me. Note: I built `Debug` since I expected the need to debug asserts / segfaults / etc.





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