STRUCT DSO_ID(9)

🦋 struct dso_id(9) 🦋

okay so this is a page from the Kernel API Manual, bestie — welcome to the struct dso_id glow-up tour 💅

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✨ NAME ✨

struct dso_id — literally just the struct name, no tagline, no bio. it's giving mysterious main character energy 🫶 (the original page leaves the description blank, so we're not gonna invent one, periodt).

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🌸 SYNOPSIS 🌸

struct dso_id {
    struct {
      u32 maj;
      u32 min;
      u64 ino;
      u64 ino_generation;
    };
    bool mmap2_valid;
    bool mmap2_ino_generation_valid;
    struct build_id build_id;
 };

yes bestie, that's an anonymous struct chilling inside it — nested but unnamed, iykyk 🎀

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💖 Members 💖

• {unnamed_struct} — anonymous. that's it. that's the description. no name, no notes, iconic 🙈
• mmap2_valid — are the maj, min and ino fields valid? this bool is the vibe check for that trio ⭐
• mmap2_ino_generation_valid — is the ino_generation valid? heads up, this is generally false for /proc/pid/maps mmap event 👀
• build_id — a possibly populated build_id. and how do you know if it's actually populated? build_id__is_defined checks whether it is. slay 🔥

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🧚 Description 🧚

so what is this thing? it's data about backing storage DSO, and it comes from three places, no cap:

• PERF_RECORD_MMAP2 meta events
• reading from /proc/pid/maps
• synthesis of build_ids from DSOs

⚠️ and the tea: it's possibly incomplete at any particular use. so don't come for it, it's doing its best 😭

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🌈 SEE ALSO 🌈

• Kernel file ./tools/perf/util/dso.h
• enum dso_binary_type(9)

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and that's the whole page, bestie 💜 this came to you from ./tools/perf/util, dated October 2026 — take care of her, she's a legend 👑✨