STRUCT CXL_REGION(9)

💅 struct cxl_region — CXL region

okay so this is struct cxl_region(9) from the Kernel API Manual, and honestly? it's kind of the main character of the CXL world. bestie, this is the struct that is the region — a chunk of CXL address space the kernel knows and loves. let's get into it 🎀

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✨ NAME ✨

struct cxl_region — literally the CXL region struct, that's it, that's the whole vibe 💖

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🌸 SYNOPSIS 🌸

here's the whole thing, copy-paste energy, not one field changed:

struct cxl_region {
    struct device dev;
    int id;
    struct cxl_root_decoder *cxlrd;
    struct range hpa_range;
    enum cxl_partition_mode mode;
    enum cxl_decoder_type type;
    struct cxl_nvdimm_bridge *cxl_nvb;
    struct cxl_pmem_region *cxlr_pmem;
    unsigned long flags;
    struct cxl_region_params params;
    struct access_coordinate coord[ACCESS_COORDINATE_MAX];
    struct notifier_block node_notifier;
    struct notifier_block adist_notifier;
    struct notifier_block mce_notifier;
 };

look at her. iconic. 👑

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🦋 Members 🦋

let me introduce you to every single member, no skipping, no cap:

• dev — this region's device. it's the region's whole identity in the device model 🫶
• id — this region's id. and this one's important: the id is globally unique across all regions, so like. no two regions are out here twinning 💅
• cxlrd — the region's root decoder. its cxlrd bestie, if you will 🌈
• hpa_range — the address range occupied by the region. so — where it lives, physically 📍
• mode — the operational mode of the mapped capacity ⚙️
• type — the endpoint decoder target type 🎯
• cxl_nvb — the nvdimm bridge, there to coordinate cxlr_pmem setup / shutdown. teamwork fr fr 🤝
• cxlr_pmem — (for pmem regions) a cached copy of the nvdimm bridge. cached! like a little save file 💾
• flags — region state flags 🚩
• params — active + config params for the region. both eras of params, together 🎀
• coord — QoS access coordinates for the region. quality-of-service tea ☕
• node_notifier — notifier for setting the access coordinates to node 📬
• adist_notifier — notifier for calculating the abstract distance of node 📐
• mce_notifier — notifier for MCE ⚠️

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🔥 SEE ALSO 🔥

go read these next, bestie, they're all connected:

Kernel file ./drivers/cxl/cxl.h, cxl objects(9), struct cxl_decoder(9), struct cxl_endpoint_decoder(9), struct cxl_switch_decoder(9), struct cxl_rd_ops(9), struct cxl_root_decoder(9), struct cxl_region_params(9), struct cxl_port(9), struct cxl_root(9), struct cxl_dport(9), struct cxl_ep(9), struct cxl_region_ref(9), struct cxl_endpoint_dvsec_info(9)

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ngl the whole struct is giving very much "organized chaos that absolutely slays" — every field has a job and every job has a field 🧚

and that's the page!! shipped from ./drivers/cxl, dated October 2026, and archived forever as struct cxl_region(9). mwah, go read the kernel source, ily 💜✨