UNION LOADER_MSG_HEADER(9)

💅 union loader_msg_header(9) — bestie edition ✨

okay so you're reading a Kernel API Manual page, and the star of the show is union loader_msg_header, aka the ISHTP firmware loader message header. That's it, that's the whole vibe. It's the little header that says what an ISHTP firmware loader message is. 🎀

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🌸 NAME 🌸

union loader_msg_header — ISHTP firmware loader message header. no cap, that's literally what it is 🫶

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✨ SYNOPSIS ✨

here's the whole thing, bestie, look at her:

union loader_msg_header {
    struct {
      __u32 command:7;
      __u32 is_response:1;
      __u32 has_next:1;
      __u32 reserved:15;
      __u32 status:8;
    };
    __u32 val32;
 };

she's a union, she's got an anonymous struct tucked inside, and she's doing bitfields. main character energy fr fr 🔥

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🦋 Members 🦋

okay, meet the cast, one by one, no skipping 👑

• {unnamed_struct} — an anonymous struct. it's just... there. no name. mysterious. we love an enigma 🙈
• command — the command type. tells you what kind of message this is 💫
• is_response — indicates if the message is a response. yep, that's the whole job 🫡
• has_next — indicates if there is a next message. so you know whether to keep scrolling, basically 💅
• reserved — reserved for future use. it's saving a seat for someone, we don't know who yet 🎀
• status — the status of the message. the vibe check, if you will ⭐
• val32 — the entire header as a 32-bit value. like the whole squad in one group photo, iconic 🌈

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💜 SEE ALSO 💜

go look at these, they're all in the Kernel file ./drivers/hid/intel-ish-hid/ishtp/loader.h:

• struct loader_xfer_query(9)
• struct loader_version(9)
• struct loader_capability(9)
• struct loader_xfer_query_ack(9)
• struct loader_xfer_fragment(9)
• struct loader_xfer_fragment_ack(9)
• struct fragment_dscrpt(9)
• struct loader_xfer_dma_fragment(9)
• struct loader_start(9)
• struct loader_start_ack(9)
• struct ish_firmware_variant(9)
• ishtp_loader_work(9)
• struct ish_global_manifest(9)

like, that's the whole friend group. go say hi 🧚

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real talk: reserved is reserved for future use — don't go filling it in with your own little experiments, bestie, it's not yours 💀

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and that's the page! 🍓 brought to you from ./drivers/hid/intel-ish-hid/ishtp, dated October 2026, and yes this is union loader_msg_header(9) signing off. mwah 💖✨