STRUCT TTM_KMAP_ITER_IOMAP(9)

💖 struct ttm_kmap_iter_iomap(9) 💖

okay bestie, welcome to the Kernel API Manual ✨ — we're about to talk about struct ttm_kmap_iter_iomap, which is literally the special-est little specialization for a struct io_mapping + struct sg_table backed struct ttm_resource. no cap, this one's a whole vibe 🦋

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🌸 NAME 🌸

struct ttm_kmap_iter_iomap — Specialization for a struct io_mapping + struct sg_table backed struct ttm_resource. it's giving "i'm a kmap iterator but make it iomap-flavored" 💅

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✨ SYNOPSIS ✨

struct ttm_kmap_iter_iomap {
    struct ttm_kmap_iter base;
    struct io_mapping *iomap;
    struct sg_table *st;
    resource_size_t start;
    struct {
      struct scatterlist *sg;
      pgoff_t i;
      pgoff_t end;
      pgoff_t offs;
    } cache;
 };

like, look at her. she's got a base, she's got an iomap, she's got the whole cache situation going on. main character energy fr fr 👑

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🎀 Members 🎀

• base — the embedded struct ttm_kmap_iter that provides the usage interface. she's the personality, the public face, the way you actually talk to this struct 🫶
• iomap — a struct io_mapping representing the underlying linear io_memory. iconic, honestly.
• st — the sg_table into iomap, representing the memory of the struct ttm_resource. it's literally the whole point of the operation.
• start — the offset that needs to be subtracted from st to make sg_dma_address(st->sgl) - start == 0 for iomap start. it's a little math, but we love her for it 💜
• cache — the scatterlist traversal cache for fast lookups. because bestie, nobody wants to walk the whole sg list every single time 🙈
• cache.sg — pointer to the currently cached scatterlist segment. the segment of the moment, the one we're emotionally attached to rn.
• cache.i — first index of sg, at PAGE_SIZE granularity. first index behavior only, no cap.
• cache.end — last index + 1 of sg, at PAGE_SIZE granularity. yes, + 1. that's not a typo, that's the API, slay.
• cache.offs — first offset into iomap of sg, at PAGE_SIZE granularity. the offs girlies rise 🌸

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👑 SEE ALSO 👑

y'all gotta check the Kernel file ./include/drm/ttm/ttm_resource.h and honestly the whole friend group:

• TTM_NUM_MOVE_FENCES(9)
• enum ttm_lru_item_type(9)
• struct ttm_lru_item(9)
• ttm_lru_item_init(9)
• struct ttm_resource_manager(9)
• struct ttm_bus_placement(9)
• struct ttm_resource(9)
• ttm_lru_item_to_res(9)
• struct ttm_lru_bulk_move_pos(9)
• struct ttm_lru_bulk_move(9)
• struct ttm_resource_cursor(9)
• struct ttm_kmap_iter_linear_io(9)
• ttm_resource_manager_set_used(9)
• ttm_resource_manager_used(9)
• ttm_resource_manager_cleanup(9)
• ttm_resource_manager_for_each_res(9)

so many references, so many icons 🧚💖 iykyk.

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okay that's the whole page bestie. every member, every field, every SEE ALSO — we kept it exactly as it is, no inventing, no skipping. periodt. 💅

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and that's a wrap, babe 🎀 this page lives in ./include/drm/ttm and it's dated October 2026, courtesy of struct ttm_kmap_iter_iomap(9) — go forth and kmap responsibly, bestie 🌈⭐