libnvme(9)

💖 libnvme(9) — the API Manual, bestie edition 💖

okay so this is a page from the libnvme API manual (section 9, kernel/API vibes) and it's literally all about one struct. yes. one. struct. and honestly? she's iconic.

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✨ NAME ✨

struct nvme_resv_status — the Reservation Status Data Structure 🎀

like, it's the data structure that holds your reservation status. that's the whole gig. no cap.

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🌸 SYNOPSIS 🌸

here's the shape of her, exactly as written, do not touch, do not "fix", she's perfect:

struct nvme_resv_status {
    __le32 gen;
    __u8 rtype;
    __u8 regstrnt[2];
    __u8 rsvd7[2];
    __u8 ptpls;
    __u8 rsvd10[14];
    union {
      struct {
        __u8 rsvd24[40];
        struct nvme_registrant_ext registrant_eds[0];
      };
      struct nvme_registrant registrant_ds[0];
    };
 };

no i will not be normal about the anonymous union. it's giving nesting doll energy 🪆

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👑 Members 👑

okay bestie, field by field, let's go. every single one. line up. 💅

• gen — the Generation. she's a __le32. that's little-endian, iykyk.
• rtype — the Reservation Type. a __u8. tells you what kind of reservation we're dealing with.
• regstrnt — Number of Registrants. a __u8[2] array, so two bytes of registrant-counting realness.
• rsvd7 — Reserved. a __u8[2]. don't touch, she's padding, she's resting.
• ptpls — Persist Through Power Loss State. a __u8. yes it's spelled "Persist Through Power Loss". yes the power loss is real. 😭
• rsvd10 — Reserved. a __u8[14]. fourteen whole bytes of "nothing to see here". queen of minding her own business.
• {unnamed_union} — anonymous. that's literally all it says. unnamed. no name. main character with no name tag 🫶
• {unnamed_struct} — anonymous. again. nesting inside the anonymous union. it's anonymous-ception fr fr.
• rsvd24 — Reserved. a __u8[40]. forty bytes. forty. reserved. we love a spacious icon.
• registrant_eds — Registrant Extended Data Structure. type struct nvme_registrant_ext, declared as registrant_eds[0] — a flexible array member, zero length, lives inside the anonymous struct. the extended one. 🌈
• registrant_ds — Registrant Data Structure. type struct nvme_registrant, declared as registrant_ds[0] — the other flexible array member, this one directly in the anonymous union. the non-extended one. ⭐

lowkey important: those two [0] array members live in different branches of the union, and both branch wrappers are anonymous — that's what the two {unnamed_union} / {unnamed_struct} entries mean. do not go renaming them, they're anonymous on purpose 💀

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🦋 vibe check 🦋

so to recap the whole lore: gen, rtype, regstrnt, rsvd7, ptpls, rsvd10, then an anonymous union of an anonymous struct (rsvd24, registrant_eds) and registrant_ds. that's it. that's the struct. and she ate. 🔥

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🎀 that's the whole page, bestie! this little love letter came from the libnvme API manual, dated October 2026, and it's documenting struct nvme_resv_status — same title, same manual, same date, all the vibes and all the facts intact. mwah 💖✨