libnvme(9)

🌸 NAME 🌸

okay bestie, welcome to the libnvme girlies' corner of section 9 💅 — today we're talking about struct libnvme_uring_cmd, which is, and I quote, the nvme uring command structure. that's it. that's the whole name. she's a struct, she lives in libnvme, she handles uring commands. iconic behavior honestly 🎀

✨ SYNOPSIS ✨

here's her whole lewk, no notes, exactly as she is 👑

struct libnvme_uring_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 rsvd2;
 };

like, she's got layers and she's got range 🦋

🫶 Members 🫶

lowkey the real main characters are the fields. let's do a vibe check on every single one of them, fr fr 🌈

• opcode — the Operation code ✨ see enum libnvme_io_opcodes and enum libnvme_admin_opcodes if you wanna know your options. she's the "what are we even doing here" field.
• flags — not supported!! 😭 it's intended for command flags (eg: SGL, FUSE) but like... it's not doing that rn. don't @ her.
• rsvd1 — Reserved for future use 💤 the placeholder bestie keeping a seat warm.
• nsid — Namespace Identifier, or Fabrics type 🌸 dual-purpose queen. she contains multitudes.
• cdw2 — Command Dword 2 💅 (no spec defined use — she's just there for the vibes, ngl)
• cdw3 — Command Dword 3 🎀 (also no spec defined use. matching set with cdw2, we love a duo)
• metadata — User space address to metadata buffer (NULL if not used) 🧚 if you're not using her, she's NULL, and that's valid.
• addr — User space address to data buffer (NULL if not used) 📍 same energy as her sister above. no buffer? NULL. simple as.
• metadata_len — Metadata buffer transfer length 📏 how much metadata we're transferring, bestie.
• data_len — Data buffer transfer length 📦 how much data we're transferring. keep up.
• cdw10 — Command Dword 10 🔥 (command specific — so like, it depends, iykyk)
• cdw11 — Command Dword 11 🔥 (command specific, again. they're a set, periodt)
• cdw12 — Command Dword 12 🔥 (command specific. yes we're still going)
• cdw13 — Command Dword 13 🔥 (command specific. half way through the dword parade 🎉)
• cdw14 — Command Dword 14 🔥 (command specific. almost there girlies)
• cdw15 — Command Dword 15 🔥 (command specific. last of the dword girlies, we made it 😭)
• timeout_ms — if it's non-zero, it overrides the system default timeout, in milliseconds ⏱️ so like, she's the "actually, we're doing it on my schedule" field. main character energy fr.
• rsvd2 — Reserved for future use (and fills an implicit struct pad 💀 yes the sentence ends like that, i'm just the messenger bestie. she's reserved AND she's structural. a multi-hyphenate 👑)

quick note diva: flags is genuinely not supported, so don't go planning your SGL/FUSE era around it, okay? it's giving "coming soon" and we respect the waitlist 🙈

and that's the whole struct, bestie!! go forth and command your uring devices responsibly 💖✨

oh and before i forget — this little love letter is from struct libnvme_uring_cmd, libnvme(9), dated October 2026 🗓️💜 mwah, see u in the group chat 🫶🎀