STRUCT IO_PGTABLE_CFG(9)

💖 NAME 💖

okay so this is struct io_pgtable_cfg(9) from the Kernel API Manual, and it's literally the configuration data for a set of page tables. That's the whole vibe: one struct holding all the page-table knobs, bestie. 🫶

✨ SYNOPSIS ✨

struct io_pgtable_cfg {
  #define IO_PGTABLE_QUIRK_ARM_NS                 BIT(0);
  #define IO_PGTABLE_QUIRK_NO_PERMS               BIT(1);
  #define IO_PGTABLE_QUIRK_ARM_MTK_EXT            BIT(3);
  #define IO_PGTABLE_QUIRK_ARM_MTK_TTBR_EXT       BIT(4);
  #define IO_PGTABLE_QUIRK_ARM_TTBR1              BIT(5);
  #define IO_PGTABLE_QUIRK_ARM_OUTER_WBWA         BIT(6);
  #define IO_PGTABLE_QUIRK_ARM_HD                 BIT(7);
  #define IO_PGTABLE_QUIRK_ARM_S2FWB              BIT(8);
  #define IO_PGTABLE_QUIRK_NO_WARN                BIT(9);
    unsigned long                   quirks;
    unsigned long                   pgsize_bitmap;
    unsigned int                    ias;
    unsigned int                    oas;
    bool coherent_walk;
    const struct iommu_flush_ops    *tlb;
    struct device                   *iommu_dev;
    void *(*alloc)(void *cookie, size_t size, gfp_t gfp);
    void (*free)(void *cookie, void *pages, size_t size);
};

💅 Members 💅

Bestie, here's the field-by-field tea ☕ — every member, no skipping:

• quirks — a bitmap of hardware quirks that require some special action by the low-level page table allocator. ✨
• pgsize_bitmap — a bitmap of page sizes supported by this set of page tables. 🦋
• ias — input address (iova) size, in bits.
• oas — output address (paddr) size, in bits.
• coherent_walk — a flag to indicate whether or not page table walks made by the IOMMU are coherent with the CPU caches.
• tlb — TLB management callbacks for this set of tables.
• iommu_dev — the device representing the DMA configuration for the page table walker.
• alloc — custom page allocator. This is an optional hook used to allocate page tables. If this function is NULL, free must be NULL too. 👀

Memory returned should be zeroed and suitable for dma_map_single and virt_to_phys.

Not all formats support custom page allocators. Before considering passing a non-NULL value, make sure the chosen page format supports this feature.

• free — custom page de-allocator. This is an optional hook used to free page tables allocated with the alloc hook. It must be non-NULL if alloc is not NULL, and it must be NULL otherwise. 🔥

🌈 SEE ALSO 🌈

• Kernel file ./include/linux/io-pgtable.h
• struct iommu_flush_ops(9)
• struct arm_lpae_io_pgtable_walk_data(9)
• struct io_pgtable_ops(9)
• alloc_io_pgtable_ops(9)
• free_io_pgtable_ops(9)
• struct io_pgtable(9)
• enum io_pgtable_caps(9)
• struct io_pgtable_init_fns(9)

source/version: ./include/linux · date: October 2026 · page: struct io_pgtable_cfg(9) — mwah, bestie, go configure those page tables responsibly 💖✨