STRUCT IOMMU_IOAS_NOIOMMU_GET_PA(9)

💅 struct iommu_ioas_noiommu_get_pa — ioctl(IOMMU_IOAS_NOIOMMU_GET_PA)

okay so bestie, welcome to the struct iommu ... iommu_get_pa(9) page from the Kernel API Manual 🦋 — this is the one about the ioctl called IOMMU_IOAS_NOIOMMU_GET_PA, and honestly? it's giving "niche but iconic" ✨

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🌸 SYNOPSIS 🌸

like, here's the whole struct, exactly as it is, no notes:

struct iommu_ioas_noiommu_get_pa {
    __u32 size;
    __u32 flags;
    __u32 ioas_id;
    __u32 __reserved;
    __aligned_u64 iova;
    __aligned_u64 length;
    __aligned_u64 out_phys;
 };

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🎀 MEMBERS 🎀

every field, every vibe check, let's go:

• size — this is just sizeof(struct iommu_ioas_noiommu_get_pa). it's literally the struct measuring itself 🪞
• flags — reserved! must be 0 for now. no cap, don't be creative here 🙈
• ioas_id — the IOAS ID you're querying the IOVA→PA mapping from 👑
• __reserved — must be 0. that's it. that's the whole job 💀
• iova — the IOVA you want to query, bestie 🔍
• length — okay so this one's a two-way field and it's lowkey the main character: on input, it's a non-zero maximum number of bytes to query starting from iova. on output, it's the number of physically contiguous bytes starting from out_phys, capped by the input length 🎀
• out_phys — the output physical address that the IOVA maps to. the answer fr fr 🫶

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🔥 DESCRIPTION 🔥

so what does it do? it queries the physical address backing an IOVA range 💫

the rules, and yes these are rules:

• the beginning of the range must already be mapped
• length must be non-zero

⚠️ big warning energy: this is for noiommu devices doing unsafe DMA only. read that again. unsafe DMA. we are not being careful here and you should know that going in 😭

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👑 SEE ALSO 👑

the whole friend group, gathered for you 💖 — kernel file ./include/uapi/linux/iommufd.h, plus:

• General ioctl format(9)
• struct iommu_destroy(9)
• struct iommu_ioas_alloc(9)
• struct iommu_iova_range(9)
• struct iommu_ioas_iova_ranges(9)
• struct iommu_ioas_allow_iovas(9)
• enum iommufd_ioas_map_flags(9)
• struct iommu_ioas_map(9)
• struct iommu_ioas_map_file(9)
• struct iommu_ioas_copy(9)
• struct iommu_ioas_unmap(9)
• enum iommufd_option(9)
• enum iommufd_option_ops(9)
• struct iommu_option(9)
• enum iommufd_vfio_ioas_op(9)
• struct iommu_vfio_ioas(9)
• enum iommufd_hwpt_alloc_flags(9)
• enum iommu_hwpt_vtd_s1_flags(9)
• struct iommu_hwpt_vtd_s1(9)
• struct iommu_hwpt_arm_smmuv3(9)
• struct iommu_hwpt_amd_guest(9)
• enum iommu_hwpt_data_type(9)
• struct iommu_hwpt_alloc(9)
• enum iommu_hw_info_vtd_flags(9)
• struct iommu_hw_info_vtd(9)
• enum iommu_hw_info_arm_smmuv3_flags(9)
• struct iommu_hw_info_arm_smmuv3(9)
• struct iommu_hw_info_tegra241_cmdqv(9)
• struct iommu_hw_info_amd(9)
• enum iommu_hw_info_type(9)
• enum iommufd_hw_capabilities(9)
• enum iommufd_hw_info_flags(9)
• struct iommu_hw_info(9)
• struct iommu_hwpt_set_dirty_tracking(9)
• enum iommufd_hwpt_get_dirty_bitmap_flags(9)
• struct iommu_hwpt_get_dirty_bitmap(9)
• enum iommu_hwpt_invalidate_data_type(9)
• enum iommu_hwpt_vtd_s1_invalidate_flags(9)
• struct iommu_hwpt_vtd_s1_invalidate(9)
• struct iommu_viommu_arm_smmuv3_invalidate(9)
• struct iommu_hwpt_invalidate(9)
• enum iommu_hwpt_pgfault_flags(9)
• enum iommu_hwpt_pgfault_perm(9)
• struct iommu_hwpt_pgfault(9)
• enum iommufd_page_response_code(9)
• struct iommu_hwpt_page_response(9)
• struct iommu_fault_alloc(9)
• enum iommu_viommu_type(9)
• struct iommu_viommu_tegra241_cmdqv(9)
• struct iommu_viommu_alloc(9)
• struct iommu_vdevice_alloc(9)
• struct iommu_ioas_change_process(9)
• enum iommu_veventq_flag(9)
• struct iommufd_vevent_header(9)
• enum iommu_veventq_type(9)
• struct iommu_vevent_arm_smmuv3(9)
• struct iommu_vevent_tegra241_cmdqv(9)
• struct iommu_veventq_alloc(9)
• enum iommu_hw_queue_type(9)
• struct iommu_hw_queue_alloc(9)

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that's the whole page, you ate it up 💅✨ this cutie lives at ./include/uapi/linux and the version stamp says October 2026 — so like, futuristic bestie behavior, slay 🎀🦋🌸💜