STRUCT RPI_FIRMWARE_PROPERTY_TAG_HEADER(9)

🎀 struct rpi_firmware_property_tag_header (9) 🎀

okay so welcome to the Kernel API Manual, bestie — this is the page for struct rpi_firmware_property_tag_header, aka the Firmware property tag header. No cap, it's giving “metadata but make it struct” energy. 🦋

💖 NAME 💖

struct rpi_firmware_property_tag_header — Firmware property tag header. That's the name, bestie, and yes it's a struct. 🫶

✨ SYNOPSIS ✨

the way this struct is shaped is literally this, so don't freestyle the fields:

struct rpi_firmware_property_tag_header {
    u32 tag;
    u32 buf_size;
    u32 req_resp_size;
 };

🧚 Members 🧚

okay so there are three members, and they all matter. Member check, let's go: 💅

• tag — one of enum_mbox_property_tag. Pick your tag from the enum and slay. ✨
• buf_size — the number of bytes in the value buffer following this struct. Literally the size of the buffer that comes after the header. 🍓
• req_resp_size — miss girl is doing double duty:
  • On submit, it's the length of the request (though it doesn't appear to be currently used by the firmware). So yeah, submit-time length, but the firmware doesn't seem to be using it right now. 👀
  • On return, it's the length of the response (always 4 byte aligned), with the low bit set. Read that again: always 4 byte aligned, and low bit set. 🔥

bestie, do not forget the low bit on the return side — it's literally what the page says. 😭

👑 SEE ALSO 👑

go look at these too, iykyk:

• Kernel file ./include/soc/bcm2835/raspberrypi-firmware.h
• struct rpi_firmware_get_voltage_request(9)
• struct rpi_firmware_clk_rate_request(9)

okay bye bestie — this page came from ./include/soc/bcm2835, dated October 2026, and that's the whole manual-page vibe 💅🦋