STRUCT NVDIMM_EFI_LABEL(9)

💖 struct nvdimm_efi_label(9) — namespace superblock 💖

okay so bestie, we're in the Kernel API Manual today and the main character is struct nvdimm_efi_label. It's literally the namespace superblock. That's it, that's the whole vibe. She's a label. She holds the metadata. She's iconic and she knows it. 🎀

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✨ NAME ✨

struct nvdimm_efi_label — namespace superblock. no cap, that's literally what the man page says and we're not gonna argue with it 🫶

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🌸 SYNOPSIS 🌸

struct nvdimm_efi_label {
    u8 uuid[NSLABEL_UUID_LEN];
    u8 name[NSLABEL_NAME_LEN];
    __le32 flags;
    __le16 nlabel;
    __le16 position;
    __le64 isetcookie;
    __le64 lbasize;
    __le64 dpa;
    __le64 rawsize;
    __le32 slot;
    u8 align;
    u8 reserved[3];
    guid_t type_guid;
    guid_t abstraction_guid;
    u8 reserved2[88];
    __le64 checksum;
 };

look at her. seventeen fields. she's serving structure realness 💅

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🦋 Members 🦋

time for the roll call, bestie, get your notes app open 📝

• uuid — the UUID per RFC 4122. yeah, the real one, not a knockoff 💜
• name — optional name, and it's NULL-terminated (so like, don't forget the \0 or she'll keep reading past the end and it's gonna be a whole thing 😭)
• flags — go see NSLABEL_FLAG_* for the details, iykyk
• nlabel — num labels to describe this ns. that's the number of labels doing the describing, fr fr
• position — labels position in set. she's gotta know her spot in the lineup 👑
• isetcookie — interleave set cookie. a cookie!! 🍓 (technically it's an interleave set cookie but still)
• lbasize — LBA size in bytes, or 0 for pmem. zero means pmem, that's the rule, don't come for me
• dpa — DPA of NVM range on this DIMM
• rawsize — size of namespace
• slot — slot of this label in label area
• align — physical address alignment of the namespace
• reserved — reserved. she's reserved. respect her privacy 🙈
• type_guid — a copy of struct acpi_nfit_system_address.range_guid
• abstraction_guid — the personality id (btt, btt2, fsdax, devdax....). yes personality id, she contains multitudes ✨
• reserved2 — reserved (again, still reserved, still not our business)
• checksum — fletcher64 sum of this object. fletcher64 specifically. not fletcher32, not some other checksum, fletcher64, periodt 🔥

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🌈 SEE ALSO 🌈

the kernel file is ./drivers/nvdimm/label.h and honestly go read the whole friend group:

• struct nd_namespace_index(9)
• struct cxl_region_label(9)
• struct nvdimm_cxl_label(9)
• struct nd_label_id(9)

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lowkey a reminder: reserved and reserved2 are literally named reserved. that's not a hint to get creative. leave them alone bestie 💀

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and that's the page!! 🧚 from ./drivers/nvdimm, dated October 2026, in the Kernel API Manual — mwah, slay, go read some label structs, ily ⭐💖