preamble_index(9)

💖 preamble_index(9) 💖

hiii bestie ✨ welcome to the Kernel API Manual, where we read kernel source so you don't have to (jk, you absolutely should, but like… together 💅). Today's main character is preamble_index(9) — the little setup gremlin that gets all your variables ready before the nd_label_* routines do their thing. no cap, it's giving "prep work that nobody claps for but everything falls apart without" 🫶

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🌸 NAME 🌸

preamble_index — the common variable initialization for the nd_label_* routines. literally just the shared setup, bestie 🎀

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✨ SYNOPSIS ✨

bool preamble_index (struct nvdimm_drvdata *ndd , int idx , struct
nd_namespace_index **nsindex_out , unsigned long **free , u32 *nslot );

she returns a bool, she takes five args, she's iconic 👑

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🦋 ARGUMENTS 🦋

okay so here's who's who in the group chat:

• ndd — the dimm container for the relevant label set. the vibe check container, if you will 🧚
• idx — the namespace_index index. yes it's an index into an index, don't ask, it's fine 🌈
• nsindex_out — on return, set to the currently active namespace index. she's an output param, she reports back 💌
• free — on return, set to the free label bitmap in the index. the "what's still available" map, slay 🗺️
• nslot — on return, set to the number of slots in the label space. the headcount, basically ⭐

fr fr bestie, notice that nsindex_out, free and nslot are all on return values — so like, you pass the pointer in, the function fills in the answer. don't be out here reading them before the call 💀

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👀 SEE ALSO 👀

Kernel file ./drivers/nvdimm/label.c — go read it, it's right there, iykyk 📖💜

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and that's the whole page bestie 🎀 this one came to you from ./drivers/nvdimm, dated October 2026, filed under preamble_index(9) — go forth and initialize those variables, mwah 💋✨