zephyr-kernel-datapassing

name	zephyr-kernel-datapassing
description	Enhances the knowledge of an AI agent with all kernel objects and subsystems used to pass data between threads and ISRs in Zephyr OS. Use this skill when you need to implement, explain, or debug data passing mechanisms (FIFO, LIFO, Stack, Message Queue, Mailbox, Pipe, ZBus, Ring Buffer).

Zephyr Kernel Data Passing

Overview

This skill provides expert knowledge on Zephyr kernel objects and subsystems used for data passing. It helps in selecting the right mechanism for the task and provides implementation details.

Workflow

1. Selection Strategy

To choose the correct data passing mechanism, first determine the requirements:

• Participants: Thread-to-Thread? ISR-to-Thread? One-to-Many?
• Data Size: Fixed small structure? Arbitrary size? Byte stream?
• Behavior: FIFO? LIFO? Synchronous? Pub/Sub?
• Coupling: Tight (direct reference) or loose (decoupled)?

Step 1: Read references/comparison.md to see the features, pros, cons, and a decision flowchart.

2. Implementation

Once the mechanism is selected, use the implementation guide to write the code.

Step 2: Read the appropriate reference:

• Kernel Objects: references/data_passing.md for FIFO, LIFO, Stack, Message Queue, Mailbox, Pipe.
• ZBus (Pub/Sub): references/zbus.md for publish-subscribe communication.
• Ring Buffer: references/ring_buffer.md for low-level byte stream buffering.

3. API & Configuration

For API signatures, Kconfig options, and sample locations.

Step 3: Read references/api.md for:

• Complete API function signatures.
• Kconfig options for each mechanism.
• Header file and sample locations.

4. Troubleshooting

If debugging data passing issues, refer to the Common Pitfalls section at the end of references/data_passing.md.

Source Locations

Description	Path
Data Passing Docs	<zephyr-ws-dir>/zephyr/doc/kernel/services/data_passing
ZBus Docs	<zephyr-ws-dir>/zephyr/doc/services/zbus/
Kernel Header	<zephyr-ws-dir>/zephyr/include/zephyr/kernel.h
ZBus Header	<zephyr-ws-dir>/zephyr/include/zephyr/zbus/zbus.h
Ring Buffer Header	<zephyr-ws-dir>/zephyr/include/zephyr/sys/ring_buffer.h
MsgQ Sample	<zephyr-ws-dir>/zephyr/samples/kernel/msg_queue
ZBus Samples	<zephyr-ws-dir>/zephyr/samples/subsys/zbus/
Philosophers Sample	<zephyr-ws-dir>/zephyr/samples/philosophers