STRUCT DAX_REGION(9)

💅 struct dax_region(9) — like, the actual manual page, bestie ✨

okay so this is a page straight outta the Kernel API Manual, and it's all about struct dax_region — the mapping infrastructure for dax devices 🎀. Yes, infrastructure. It's giving scaffolding-but-make-it-serve-caffeine. Let's get into it 💖

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✨ NAME ✨

struct dax_region — the mapping infrastructure for dax devices 🦋

lowkey the whole personality of this thing is "I hold the vibes together so the dax devices can do their thing." iconic behavior, no cap 👑

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🌸 SYNOPSIS 🌸

here's the whole struct, exactly as it lives, don't touch, don't rename, just admire:

struct dax_region {
    int id;
    int target_node;
    struct kref kref;
    struct device *dev;
    unsigned int align;
    struct ida ida;
    struct resource res;
    struct device *seed;
    struct device *youngest;
 };

look at her. nine members. main character energy fr fr 💅

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🫶 Members 🫶

every single field, and what it's actually here for 👇

• id — a kernel-wide unique region for a memory range. like a government name but for memory. one of one, periodt 🆔
• target_node — the effective numa node if this memory range is onlined. yes, if — conditional queen 🙈
• kref — the refcount you pin while other agents have a need to do lookups. basically holding the door open for your friends 🚪💖
• dev — the parent device backing this region. the parent! the backer! the one paying rent 🏠
• align — the allocation and mapping alignment for child dax devices. everything lines up. literally. 📐✨
• ida — the instance id allocator. handing out ids like a club promoter with a clipboard 🎟️
• res — the resource tree that tracks instance allocations. tree. tracking. very organized of her 🌳
• seed — allows userspace to find the first unbound seed device. first! unbound! mysterious! 🌱
• youngest — allows userspace to find the most recently created device. the baby of the family, freshly made 👶🔥

ngl, the seed and youngest duo is such a cute pairing — first-ever and newest-ever, both findable from userspace 🧚

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🌈 SEE ALSO 🌈

go read these next, iykwim 👀

• Kernel file ./drivers/dax/dax-private.h
• struct dax_mapping(9)
• struct dev_dax_range(9)
• struct dev_dax(9)

all of them live together in ./drivers/dax and honestly? found family 🫶

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that's the whole page bestie, every member accounted for, nothing skipped, nothing invented 💜 mwah 💋

source/version: ./drivers/dax · date: October 2026 — slay, dated, and official ✨🎀💖