STRUCT MHI_BUF(9)

💅 struct mhi_buf(9) — the Kernel API Manual, but make it make sense

okay bestie, so this whole page is about one lil struct called mhi_buf, and it's basically the "here's my buffer, here's where it lives, here's how big it is" receipt for MHI. that's it. that's the vibe. MHI Buffer description, periodt. 🎀

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✨ SYNOPSIS ✨

like, here's the actual shape of it, copy it exactly or don't come crying to me:

struct mhi_buf {
    void *buf;
    const char *name;
    dma_addr_t dma_addr;
    size_t len;
 };

that's the whole struct. four fields. iconic minimalism honestly. 🦋

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🌸 Members 🌸

so let's go through each field one by one, no skipping, i promise:

• buf — the virtual address of the buffer. yes bestie, the virtual one. it's the pointer you actually use in your code, the vibe-address, the one your CPU sees. 💖
• name — the buffer label. cute little nametag for your buffer. BUT — and this is the part where you gotta pay attention — for an offload channel, the configurations name must be:
  • ECA — Event context array data
  • CCA — Channel context array data

like, those aren't suggestions, that's literally what it must be. the kernel will be like "who is this" if you name it anything else. no cap. 🔥

• dma_addr — the IOMMU address of the buffer. so like, buf is the address you know, and dma_addr is the address the device knows after IOMMU translation. two addresses, one buffer, main character energy. ✨
• len — the # of bytes. just the count. how many bytes are we talking. that's the whole field. 💀

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🫶 SEE ALSO 🫶

okay so the kernel file lives at ./include/linux/mhi.h and it's surrounded by a whole friend group of related symbols — literally the entire MHI extended universe, i'm obsessed. here's every single one, i'm not leaving a single one out because you deserve the full list:

enum mhi_callback(9), enum mhi_flags(9), enum mhi_device_type(9), enum mhi_ch_type(9), struct image_info(9), struct mhi_link_info(9), enum mhi_ee_type(9), enum mhi_state(9), enum mhi_ch_ee_mask(9), enum mhi_er_data_type(9), enum mhi_db_brst_mode(9), struct mhi_channel_config(9), struct mhi_event_config(9), struct mhi_controller_config(9), struct mhi_controller(9), struct mhi_device(9), struct mhi_result(9), struct mhi_driver(9), mhi_alloc_controller(9), mhi_free_controller(9), mhi_register_controller(9), mhi_unregister_controller(9), __mhi_driver_register(9), mhi_driver_unregister(9), mhi_set_mhi_state(9), mhi_notify(9), mhi_get_free_desc_count(9), mhi_prepare_for_power_up(9), mhi_async_power_up(9), mhi_sync_power_up(9), mhi_power_down(9), mhi_power_down_keep_dev(9), mhi_unprepare_after_power_down(9), mhi_pm_suspend(9), mhi_pm_resume(9), mhi_pm_resume_force(9), mhi_download_rddm_image(9), mhi_force_rddm_mode(9), mhi_get_exec_env(9), mhi_get_mhi_state(9), mhi_soc_reset(9), mhi_device_get_sync(9), mhi_device_put(9), mhi_prepare_for_transfer(9), mhi_unprepare_from_transfer(9), mhi_queue_buf(9), mhi_queue_skb(9), mhi_queue_is_full(9), mhi_get_channel_doorbell_offset(9)

go read those too, iykyk. 👑

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ok so that's the whole page bestie, you ate that fr fr 🍓

and like, credits where credits are due: this came from the kernel file ./include/linux, dated October 2026 — so yeah, future-coded of it, we love that for us. stay hydrated, read your headers, mwah 💜🧚