Kernel services

Skill beriberikix/zephyr-agent-skills/skills/kernel-services

A complete catalog of Agent Skills (agentskills.io) for Zephyr RTOS development.

Install

npx -y skills add beriberikix/zephyr-agent-skills --skill kernel-services

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What its author says it does

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Advanced Zephyr RTOS kernel services. Covers inter-thread communication using Zbus (pub/sub), behavioral management with the State Machine Framework (SMF), background processing via work queues, and persistent configuration with the Settings subsystem. Trigger when building modular application architectures, complex state-driven logic, or requiring persistent data storage.

SKILL.md

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Zephyr Kernel Services

Move beyond basic threading and logging to build modular, event-driven, and robust Zephyr applications.

Core Workflows

1. Event-Driven Communication (Zbus)

Decouple your modules using a lightweight publish-and-subscribe bus.

Reference: zbus.md
Key Tools: ZBUS_CHAN_DEFINE, ZBUS_SUBSCRIBER_DEFINE, zbus_chan_pub.

2. Behavioral Logic (SMF)

Manage complex system states and transitions using the State Machine Framework.

Reference: smf.md
Key Tools: smf_set_state, SMF_CREATE_STATE, Hierarchical states.

3. Background Processing (Work Queues)

Defer long-running or non-critical tasks to prevent blocking interrupts or high-priority threads.

Reference: settings_workqueue.md
Key Tools: k_work_submit, k_work_delayable, Custom work queues.

4. Persistence (Settings)

Save and restore configuration data and state across reboots.

Reference: settings_workqueue.md
Key Tools: settings_load, settings_save_one, NVS backends.

Quick Start (Zbus)

// Define a channel for sensor data
ZBUS_CHAN_DEFINE(sensor_data_chan, struct sensor_msg, NULL, NULL, ZBUS_OBSERVERS_EMPTY, ZBUS_CHAN_DEFAULTS);

// Publish from a thread
zbus_chan_pub(&sensor_data_chan, &msg, K_NO_WAIT);

Professional Patterns (Asset Tracker Style)

Modularity: Use Zbus as the backbone for inter-module communication.
Predictability: Use SMF to define clear lifecycle states for each module (e.g., Uninitialized -> Ready -> Active -> Error).
Responsiveness: Use custom work queues for sensor data ingestion to keep the main thread responsive for cloud communication.
Sensor Integration: For sensor data ingestion patterns, see the hardware-io skill.

Automation Tools

zbus_channel_lint.py: Detect duplicate ZBUS_CHAN_DEFINE names across source files.

Examples & Templates

smf_state_table_template.c: Starter SMF state table and lifecycle wiring.

Validation Checklist

Zbus publishers and subscribers exchange messages without deadlock or missed updates.
SMF transitions follow expected state graph under normal and error conditions.
Deferred work executes on intended queue context with bounded execution time.
Settings values persist across reboot and reload successfully at startup.

Resources

References:
- zbus.md: Publish/Subscribe patterns and subscriber types.
- smf.md: Finite and Hierarchical state machine implementation.
- settings_workqueue.md: Background work and persistent storage.
Scripts:
- zbus_channel_lint.py: Zbus channel name collision checker.
Assets:
- smf_state_table_template.c: State-machine template.