Implementing an application in Rust for 'C' RTOS


I am relatively new to rust and planning on building an application for Contiki RTOS (implemented in C).

As of now I am able to write a Rust lib containing code that will be called from other Contiki applications.
But I am finding it bit tricky (with current Rust version) to create processes in an application and making OS to call it. i.e I would need to access OS's data structures in Rust app, modify it and export it. Currently with the program can be successfully compiled it crashes during run-time due to segmentation failure.

I need advice on how to approach the implementation of Rust app for an C RTOS. Are there any project examples doing the same/similar (Online search wasn't so helpful).