STRUCT FW_CDEV_SEND_RESPONSE(9)

🦋 struct fw_cdev_send_response(9) — Kernel API Manual 🦋

okay so bestie, we're in the Kernel API Manual today and this one is literally about sending an asynchronous response packet. it's giving "the request came in, now you gotta clap back" energy 💅

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✨ NAME ✨

struct fw_cdev_send_response — Send an asynchronous response packet 🎀

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🌸 SYNOPSIS 🌸

struct fw_cdev_send_response {
    __u32 rcode;
    __u32 length;
    __u64 data;
    __u32 handle;
 };

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💖 Members 💖

• rcode — the Response code, as determined by the userspace handler. like, you decide what the mood of this reply is 🫶
• length — Length of outgoing payload, in bytes. count 'em, bestie 🍓
• data — Userspace pointer to payload. this is where the actual goods live ✨
• handle — The handle from the fw_cdev_event_request. keep it safe, you'll need it 🔥

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👑 Description 👑

So here's the whole vibe: you're sending a response to an incoming request. no cap.

By setting up an address range using the FW_CDEV_IOC_ALLOCATE ioctl, userspace can listen for incoming requests. an incoming request will generate an FW_CDEV_EVENT_REQUEST, and userspace must send a reply using this ioctl — like, it's not optional, fr fr 😭

The event has a handle to the kernel-side pending transaction, and that's the one you should be using with this ioctl. main character handle energy, iykyk 💀

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🌈 SEE ALSO 🌈

Kernel file ./include/uapi/linux/firewire-cdev.h — plus the whole friend group:

• struct fw_cdev_event_common(9)
• struct fw_cdev_event_bus_reset(9)
• struct fw_cdev_event_response(9)
• struct fw_cdev_event_response2(9)
• struct fw_cdev_event_request(9)
• struct fw_cdev_event_request2(9)
• struct fw_cdev_event_request3(9)
• struct fw_cdev_event_iso_interrupt(9)
• struct fw_cdev_event_iso_interrupt_mc(9)
• struct fw_cdev_event_iso_resource(9)
• struct fw_cdev_event_phy_packet(9)
• struct fw_cdev_event_phy_packet2(9)
• union fw_cdev_event(9)
• struct fw_cdev_get_info(9)
• struct fw_cdev_send_request(9)
• struct fw_cdev_allocate(9)
• struct fw_cdev_deallocate(9)
• struct fw_cdev_initiate_bus_reset(9)
• struct fw_cdev_add_descriptor(9)
• struct fw_cdev_remove_descriptor(9)
• struct fw_cdev_create_iso_context(9)
• struct fw_cdev_set_iso_channels(9)
• struct fw_cdev_iso_packet(9)
• struct fw_cdev_queue_iso(9)
• struct fw_cdev_start_iso(9)
• struct fw_cdev_stop_iso(9)
• struct fw_cdev_flush_iso(9)
• struct fw_cdev_get_cycle_timer(9)
• struct fw_cdev_get_cycle_timer2(9)
• struct fw_cdev_allocate_iso_resource(9)
• struct fw_cdev_send_stream_packet(9)
• struct fw_cdev_send_phy_packet(9)
• struct fw_cdev_receive_phy_packets(9)

they're all icons, every single one 💜

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okay that's the page!! this lil beauty lives in ./include/uapi/linux and it's dated October 2026, so you know she's fresh 🧚✨ bye bestie, go send some responses 🎀💅