STRUCT CXL_REGISTER_MAP(9)

✨ struct cxl_register_map(9) ✨

okay so bestie, welcome to the Kernel API Manual (section 9, yes we're fancy) — this is where CXL keeps its receipt for the register block it just scavenged. 🎀

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💖 NAME 💖

struct cxl_register_map — the "DVSEC harvested register block mapping parameters" situation. basically whenever the kernel goes digging through DVSEC and pulls out a register block, THIS is the little bundle of mapping params it keeps about it. no cap. 🦋

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🌸 SYNOPSIS 🌸

struct cxl_register_map {
    struct device *host;
    void __iomem *base;
    resource_size_t resource;
    resource_size_t max_size;
    u8 reg_type;
    union {
      struct cxl_component_reg_map component_map;
      struct cxl_device_reg_map device_map;
      struct cxl_pmu_reg_map pmu_map;
    };
 };

ikyk what this is giving — a big struct with a lil anonymous union inside. main character energy fr. 👑

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🎀 Members 🎀

• host — the device that handles devm operations and logging. it's the responsible adult of the struct, basically. 🫶
• base — the virtual base of the register-block-BAR + block_offset. yes, that plus MATTERS, don't skip it bestie. 😭
• resource — the physical resource base of the register block. the realest of the addresses. 💅
• max_size — the maximum mapping size to perform the register search in. it's the "how far are we allowed to go looking" limit. ⭐
• reg_type — see enum cxl_regloc_type for what's going on here. 🔥
• {unnamed_union} — anonymous. no name, all vibes. it just IS. 💀
  • component_map — the cxl_reg_map for component registers ✨
  • device_map — the cxl_reg_maps for device registers 🌈
  • pmu_map — the cxl_reg_maps for CXL Performance Monitoring Units 🍓

tiny heads up so u don't get clowned on: component_map says cxl_reg_map (singular) while device_map and pmu_map both say cxl_reg_maps (plural). that's just how it is, don't come for me, I'm reading it straight off the page. 🙈

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🦋 SEE ALSO 🦋

the kernel file ./include/cxl/cxl.h, and then this whole lil friend group:

• enum cxl_devtype(9)
• struct cxl_dpa_perf(9)
• struct cxl_dpa_partition(9)
• struct cxl_dev_state(9)

go read them, they're literally iconic. periodt. 👑

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that's the whole page bestie, you ate that 💜 — sourced from ./include/cxl, dated October 2026, and that's the Kernel API Manual signing off. mwah 🧚