STRUCT FW_CDEV_SEND_PHY_PACKET(9)

💅 struct fw_cdev_send_phy_packet(9) 💅

okay bestie, welcome to the Kernel API Manual ✨ — yes, that's the manual name, we're in the big-kid kernel docs now, and this particular page is all about one lil struct that yeets a PHY packet across your FireWire card. slay. let's get into it 🎀

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✨ NAME ✨

struct fw_cdev_send_phy_packet — send a PHY packet 💌

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🌸 SYNOPSIS 🌸

struct fw_cdev_send_phy_packet {
    __u64 closure;
    __u32 data[2];
    __u32 generation;
 };

lowkey iconic struct, ngl. look at her. 🫶

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🦋 Members 🦋

• closure — gets passed right back to you in userspace inside the PHY-packet-sent event. it's giving "return to sender" but make it kernel 💅
• data — the first and second quadlet of the PHY packet. two quadlets, one field, we love a bundle 🎀
• generation — the bus generation where the packet is valid ⭐

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💖 Description 💖

so the FW_CDEV_IOC_SEND_PHY_PACKET ioctl sends a PHY packet to all the nodes on the same card as this device. like, everyone on the bus gets it, no gatekeeping 💀

after transmission, either FW_CDEV_EVENT_PHY_PACKET_SENT event or FW_CDEV_EVENT_PHY_PACKET_SENT event is generated. yes. that's literally what the page says. both of them. same name. i'm not fighting the docs, i'm just reporting the news 🙈

the payload data shall be specified in host byte order. and — okay, quoting the page directly here because this is a whole mood — usually, data needs to be the bitwise inverse of data. yes bestie, the field and itself. that's what it says. VersaPHY packets are an exception to this rule, so don't @ me if you're doing VersaPHY things 🌈

⚠️ heads up: the ioctl is only permitted on device files which represent a local node. no local node, no packet. that's the vibe check and you did not pass it 😭

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🔥 SEE ALSO 🔥

the kernel file that started it all: ./include/uapi/linux/firewire-cdev.h — and like, the entire 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_send_response(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_receive_phy_packets(9)

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and that's the whole page, bestie — you ate that 💅

this lil masterpiece lives at ./include/uapi/linux, dated October 2026, and it's filed under struct fw_cd...d_phy_packet(9) (the title got a little truncated on the way in, we still love her 🎀). mwah, go send some PHY packets 🦋✨💜