STRUCT SCMI_EVENT_HEADER(9)

okay so bestie, you opened the Kernel API Manual page for struct scmi_event_header(9) and honestly? It's giving “small but important utility header” energy 💅✨ Stay for the lore, because every member and every SEE ALSO ref is coming with us.

🎀 NAME 🎀

struct scmi_event_header — A utility header. That's the whole vibe: a utility header, no cap.

✨ SYNOPSIS ✨

Here's the exact shape, bestie:

struct scmi_event_header {
    ktime_t timestamp;
    size_t payld_sz;
    unsigned char evt_id;
    unsigned char payld[];
 };

🫶 Members 🫶

Okay squad, member check:

• timestamp — the timestamp, in nanoseconds (boottime), which was associated to this event as soon as it entered the SCMI RX ISR. Literally the event's little arrival receipt 🕰️.
• payld_sz — the effective size of the embedded message payload which follows. Like, the real size of the payload that's coming after it.
• evt_id — the event ID (corresponds to the Event MsgID for this Protocol). Capitalization matters, iykyk.
• payld — a reference to the embedded event payload. The payload itself, bestie 💖.

🌸 Description 🌸

This header is prepended to each received event message payload before queueing it on the related struct events_queue. So yes, the header goes in front of the payload before the queueing situation happens — very organized, very main character energy ✨.

🔥 SEE ALSO 🔥

If you want the full group chat, start with the kernel file ./drivers/firmware/arm_scmi/notify.c and Theory of operation(9), then scroll through the whole squad:

• struct scmi_notify_instance(9)
• struct events_queue(9)
• struct scmi_registered_events_desc(9)
• struct scmi_registered_event(9)
• struct scmi_event_handler(9)
• scmi_lookup_and_call_event_chain(9)
• scmi_process_event_header(9)
• scmi_process_event_payload(9)
• scmi_events_dispatcher(9)
• scmi_notify(9)
• scmi_kfifo_free(9)
• scmi_initialize_events_queue(9)
• scmi_allocate_registered_events_desc(9)
• scmi_register_protocol_events(9)
• scmi_deregister_protocol_events(9)
• scmi_allocate_event_handler(9)
• scmi_free_event_handler(9)
• scmi_bind_event_handler(9)
• scmi_valid_pending_handler(9)
• scmi_register_event_handler(9)
• __scmi_event_handler_get_ops(9)
• scmi_get_active_handler(9)
• __scmi_enable_evt(9)
• scmi_put_handler_unlocked(9)
• scmi_event_handler_enable_events(9)
• scmi_notifier_register(9)
• scmi_notifier_unregister(9)
• scmi_devm_notifier_register(9)
• scmi_devm_notifier_unregister(9)
• scmi_protocols_late_init(9)
• scmi_notification_init(9)
• scmi_notification_quiesce(9)
• scmi_notification_exit(9)

mwah 💋 this page lives under ./drivers/firmware/arm_scmi, dated October 2026, and it's the struct scmi_event_header(9) manual page — bye bestie, go slay those events 🎀✨