libnvme(2)

✨ libnvme — API Manual ✨

okay bestie, welcome to libnvme(2) 💖 this is the page where we meet struct nvme_passthru_cmd, aka the nvme passthrough command structure. yes it's a struct, yes it's giving main character energy, and yes you're gonna learn every single field, no skips, no cap 🫶

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🌸 NAME 🌸

struct nvme_passthru_cmd — the nvme passthrough command structure, your lil' backstage pass to talking straight to a controller 🎀

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⭐ SYNOPSIS ⭐

struct nvme_passthru_cmd {
    __u8 opcode;
    __u8 flags;
    __u16 rsvd1;
    __u32 nsid;
    __u32 cdw2;
    __u32 cdw3;
    __u64 metadata;
    __u64 addr;
    __u32 metadata_len;
    __u32 data_len;
    __u32 cdw10;
    __u32 cdw11;
    __u32 cdw12;
    __u32 cdw13;
    __u32 cdw14;
    __u32 cdw15;
    __u32 timeout_ms;
    __u32 result;
 };

look at her. seventeen fields. a whole queen 👑 and now let's meet each one by name.

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💅 Members 💅

this is the part where I introduce you to the whole squad, one by one, no one gets left out 💜

• opcode — the Operation code, bestie. peek at enum nvme_io_opcodes and enum nvme_admin_opcodes to see your options 👀
• flags — not supported: it's intended for command flags (for example: SGL, FUSE), but it's not actually a thing yet 🙈
• rsvd1 — Reserved for future use. she's just vibing. do not touch 🌈
• nsid — Namespace Identifier, or the Fabrics type. yes, she does double duty, we love a multitasker ✨
• cdw2 — Command Dword 2 (no spec defined use). literally no spec says what she does, iconic behavior 💀
• cdw3 — Command Dword 3 (no spec defined use). twin sister of cdw2, equally mysterious 🦋
• metadata — the user space address to the metadata buffer (NULL if not used). no metadata? just pass NULL, we're chill 🌸
• addr — the user space address to the data buffer (NULL if not used). same deal, no data means NULL honey 🫶
• metadata_len — Metadata buffer transfer length. how much metadata are we moving, babes 📏
• data_len — Data buffer transfer length. how much data are we moving, fr fr 📦
• cdw10 — Command Dword 10 (command specific). she's special to her command and only her command 💅
• cdw11 — Command Dword 11 (command specific). again, command specific 🎀
• cdw12 — Command Dword 12 (command specific). you get the vibe by now ⭐
• cdw13 — Command Dword 13 (command specific). yup 🍓
• cdw14 — Command Dword 14 (command specific). still going 💜
• cdw15 — Command Dword 15 (command specific). the last of the command-specific dword girlies, we stan a full set 🧚
• timeout_ms — if she's non-zero, she overrides the system default timeout, in milliseconds ⏱️ a little "actually, we're waiting this long" energy
• result — gets set on completion to the command's CQE DWORD 0 controller response. that's the controller talking back to you, bestie 🗣️✨

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quick reminder: flags is not supported — so don't go building your whole personality on passing SGL or FUSE through it, okay? 💖

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that's the whole struct, you ate this 🍽️💅 iykyk — and if you didn't know before, now you literally do. periodt.

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this page is part of the libnvme(2) API Manual, documenting struct nvme_passthru_cmd, dated July 2026 🌙 go forth and pass those commands through, bestie 🦋💖