STRUCT DEV_IOMMU(9)

🌸 NAME 🌸

okay so bestie, welcome to struct dev_iommu(9) from the Kernel API Manual — it's literally the collection of per-device IOMMU data 💅

Like, struct dev_iommu is the whole vibe: one lil bundle holding all the IOMMU-ish stuff that belongs to a single device. Iconic. Periodt.

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✨ SYNOPSIS ✨

struct dev_iommu {
    struct mutex lock;
    struct iommu_fault_param *fault_param;
    struct iommu_fwspec             *fwspec;
    struct iommu_device             *iommu_dev;
    void *priv;
    u32 max_pasids;
    u32 attach_deferred:1;
    u32 pci_32bit_workaround:1;
    u32 require_direct:1;
    u32 shadow_on_flush:1;
 };

no cap, that's the whole struct right there 🫶

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🎀 Members 🎀

okay let's go field by field, bestie, no skipping 👑

• fault_param — the IOMMU detected device fault reporting data. it's giving "receipts for when things go wrong" 😭
• fwspec — the IOMMU fwspec data 📎
• iommu_dev — the IOMMU device that this device is linked to. main character energy, fr fr 🔗
• priv — the IOMMU Driver private data 🙈 (yes it's private, don't be nosy)
• max_pasids — the number of PASIDs this device can consume 🔢
• attach_deferred — the dma domain attachment is deferred ⏳
• pci_32bit_workaround — Limit DMA allocations to 32-bit IOVAs 🧚
• require_direct — device requires IOMMU_RESV_DIRECT regions ⭐
• shadow_on_flush — IOTLB flushes are used to sync shadow tables 🦋

also lowkey note there's a lock (a struct mutex) sitting at the top of the struct in the synopsis — the manpage doesn't give it its own little Member blurb, so like, don't come for me, I'm just reporting what's there 💀

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🌈 Description 🌈

okay so here's the tea: this section is literally a TODO ☕

TODO: migrate other per device data pointers under iommu_dev_data, e.g. c struct iommu_group *iommu_group;

so yeah, the description is basically an "I'll finish this later" note from the kernel devs — honestly relatable, we've all been there 😭🫶

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🔥 SEE ALSO 🔥

bestie you already KNOW there's a whole friend group, all from the kernel file ./include/linux/iommu.h:

• struct iommu_fault_page_request(9)
• struct iommu_fault(9)
• enum iommu_page_response_code(9)
• struct iommu_page_response(9)
• struct iopf_queue(9)
• struct iommu_resv_region(9)
• struct iommu_iotlb_gather(9)
• struct iommu_dirty_bitmap(9)
• struct iommu_dirty_ops(9)
• struct iommu_user_data(9)
• struct iommu_user_data_array(9)
• __iommu_copy_struct_from_user(9)
• iommu_copy_struct_from_user(9)
• __iommu_copy_struct_from_user_array(9)
• iommu_copy_struct_from_user_array(9)
• iommu_copy_struct_from_full_user_array(9)
• __iommu_copy_struct_to_user(9)
• iommu_copy_struct_to_user(9)
• struct iommu_ops(9)
• struct iommu_domain_ops(9)
• struct iommu_device(9)
• struct iommu_fault_param(9)
• iommu_iotlb_gather_is_disjoint(9)
• iommu_iotlb_gather_add_range(9)
• iommu_iotlb_gather_add_page(9)
• struct iommu_fwspec(9)
• struct iommu_sva(9)
• iommu_map_sgtable(9)

like, the whole extended universe, iykyk 👑💜

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so that's the page, bestie 🎀 it lives in ./include/linux and the footer says October 2026 — mwah, go read the other ones too, ily, bye 💖