I'm trying to write a code that sends data from the Cortex-A9 processor to the Cortex-M4 processor, then the Cortex-M4 processes it, then sends the processed data to the Cortex-A9. I've run the PingPong example on M4, and it works by executing some commands from the A9 side. but I want to write a code that sends the data without using these commands. I've checked this sample and this document, but I can't relate between them. I'm not really sure Where can I start to write the Linux rpmsg code on the Cortex-A9 processor, and I'm really short on time.