STRUCT IOMMU_RESV_REGION(9)

💖 struct iommu_resv_region(9) — the Kernel API Manual glow-up ✨

okay so bestie, welcome to the struct iommu_resv_region(9) page in the Kernel API Manual — this is the little descriptor that says "hey, this chunk of memory is reserved, hands off" 🫶 it's giving bodyguard energy for physical memory, ngl.

---

🌸 NAME 🌸

struct iommu_resv_region — descriptor for a reserved memory region 💅 literally the little ID card for a slice of memory that the IOMMU has claimed as its own.

---

✨ SYNOPSIS ✨

struct iommu_resv_region {
    struct list_head        list;
    phys_addr_t start;
    size_t length;
    int prot;
    enum iommu_resv_type    type;
    void (*free)(struct device *dev, struct iommu_resv_region *region);
 };

look at her. six fields. absolutely iconic. 🎀

---

🦋 Members 🦋

so here's the member-by-member vibe check, keep up bestie:

• list — the linked list pointers 🔗 she's in a list, obviously, main character behavior.
• start — system physical start address of the region 📍 where it begins, fr fr.
• length — length of the region in bytes 📏 (bytes!! not pages!! don't come for me).
• prot — IOMMU Protection flags (READ/WRITE/...) 🛡️ the permission slip, iykyk.
• type — type of the reserved region 🏷️ which flavor of reserved we're dealing with.
• free — callback to free associated memory allocations 🧹 the cleanup crew. it's a function pointer: void (*free)(struct device *dev, struct iommu_resv_region *region).

no cap, that free callback takes the struct device *dev and the struct iommu_resv_region *region — don't lose them 💀

---

💜 SEE ALSO 💜

go read your siblings, bestie, they're all in the kernel file ./include/linux/iommu.h and honestly the whole friend group ate:

• 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_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)
• struct dev_iommu(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)

that's the whole group chat, no one gets left on read 💅

---

and that's the page!! 🎀 this lil number lives over in ./include/linux, it's dated October 2026, and it goes by struct iommu_resv_region(9) — periodt, go touch some reserved memory (respectfully) 💖✨🔥