libnvme(9)

🦋 libnvme(9) — nvme_telemetry_log, bestie edition 🦋

okay so this is a page from the API Manual for libnvme, and it's literally about the struct that holds the controller's vibes — like its inner state, its diary, its receipts. Let's get into it ✨

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✨ NAME ✨

struct nvme_telemetry_log — Retrieve internal data specific to the manufacturer.

(no cap, that's the whole pitch 💅)

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🌸 SYNOPSIS 🌸

Coded verbatim, bestie — don't touch a single character:

struct nvme_telemetry_log {
    __u8 lpi;
    __u8 rsvd1[4];
    __u8 ieee[3];
    __le16 dalb1;
    __le16 dalb2;
    __le16 dalb3;
    __u8 rsvd14[2];
    __le32 dalb4;
    __u8 rsvd20[360];
    __u8 ths;
    union {
      __u8 hostdgn;
      __u8 tcs;
    };
    __u8 ctrlavail;
    __u8 ctrldgn;
    __u8 rsnident[128];
    __u8 data_area[];
};

look at all those reserved padding bytes — she's structured, she's padded, she's iconic 🎀

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💖 Members 💖

okay so member by member, here's the tea ☕

• lpi — the Log Identifier. It's either NVME_LOG_LID_TELEMETRY_HOST or NVME_LOG_LID_TELEMETRY_CTRL. pick your fighter 🥊
• rsvd1 — Reserved. literally nothing to see here, moving on 🙈
• ieee — the IEEE OUI Identifier, aka the Organization Unique Identifier (OUI) for the controller vendor. it's the one who can actually interpret the data — the translator of the group chat 🫶
• dalb1 — Telemetry Host/Controller Initiated Data Area 1 Last Block. it's the value of the last block in this area, periodt.
• dalb2 — Telemetry Host/Controller Initiated Data Area 1 Last Block. yep, same wording as dalb1, still the value of the last block in this area. not a typo on my end, that's just how the page says it 💀
• dalb3 — Telemetry Host/ControllerInitiated Data Area 1 Last Block is the value of the last block in this area. (yes it says "ControllerInitiated" all squished together — we love a quirk 👑)
• rsvd14 — Reserved. again. the padding is padding-ing 🌈
• dalb4 — Telemetry Host/Controller Initiated Data Area 4 Last Block is the value of the last block in this area. (area 4 this time, main character energy ⭐)
• rsvd20 — Reserved. [360] bytes of "please ignore me" 💜
• ths — Telemetry Host-Initiated Scope 🌸
• {unnamed_union} — anonymous. that's it. that's the description. she has no name and she doesn't need one 🧚
• hostdgn — Telemetry Host-Initiated Data Generation Number. it's a value that gets incremented every single time the host initiates a capture of its internal controller state in the controller. it's giving counter that keeps count 🔥
• tcs — Telemetry Controller-Initiated Scope ✨
• ctrlavail — Telemetry Controller-Initiated Data Available. if it's cleared, then the controller telemetry log does not contain saved internal controller state. if this field is set to 1h, the controller log does contain saved internal controller state. and — important — if this field is set to 1h, the data will be latched until the host releases it by reading the log with RAE cleared. so don't leave her on read, bestie 😭
• ctrldgn — Telemetry Controller-Initiated Data Generation Number. a value that gets incremented each time the controller initiates a capture of its internal controller state in the controller. (the original page has a lil stray space before the period there, we're not gonna be weird about it 💅)
• rsnident — Reason Identifiers. a vendor specific identifier that describes the operating conditions of the controller at the time of capture. receipts of what was happening, basically 📸
• data_area — Telemetry data blocks, vendor specific information data. the actual payload, the main event 💖

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✨ Description ✨

so the whole thing: this log is made of a header that describes the log, plus zero or more Telemetry Data Blocks. zero! she can be a little empty! valid! 🦋

every single Telemetry Data Block is NVME_LOG_TELEM_BLOCK_SIZE, which is 512 bytes, in size. exact. no vibes-based sizing here ⭐

and what does this log actually do? it captures the controller's internal state. that's it. that's the whole flex. the controller shows you her journal, and the header tells you how to read it 📖

ngl, this whole struct is basically a header plus a dramatic pause before the vendor-specific data drops 💅

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okay that's the whole page, bestie — every member, every reserved byte, every flag, nothing skipped, nothing invented 🫶

this was libnvme(9) from the API Manual, dated October 2026 — mwah, go read your telemetry logs, ily 💜✨