ccio_io_pdir_entry(9)

okay so this is ccio_io_pdir_entry(9) from the Kernel API Manual, and it's giving “initialize an I/O Pdir” energy 💖 bestie, it's short, it's technical, and we're gonna get every little bit of it.

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✨ NAME ✨

ccio_io_pdir_entry — Initialize an I/O Pdir. That's the whole assignment, no cap. 🎀

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🌸 SYNOPSIS 🌸

the signature, verbatim, right here 🫶

void ccio_io_pdir_entry (__le64 *pdir_ptr , space_t sid , phys_addr_t
       pba , unsigned long hints );

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🦋 ARGUMENTS 🦋

• pdir_ptr — A pointer into I/O Pdir. it's literally pointing at the spot we're working with 💅
• sid — The Space Identifier. iconic little id, fr fr ✨
• pba — The physical address. the physical-address main character 👑
• hints — The DMA Hint. yes bestie, hints 🔥

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💜 DESCRIPTION 💜

okay so here's the tea: given a physical address (pba, arg2) and a space id (sid, arg1), this loads the I/O PDIR entry pointed to by pdir_ptr (arg0) 💖. each I/O Pdir entry consists of 8 bytes, laid out like this — and yes, MSB == bit 0, keep that in mind:

WORD 0:

       ┌──────────────────────────────────┐
       │ Phys     Virtual Index   Phys    │
       │ 0:3      0:11            4:19    │
       │ 4 bits   12 bits         16 bits │
       └──────────────────────────────────┘
       WORD 1:

       ┌────────────────────────────────────────────────────────────────────────┐
       │ Phys      Rsvd     Prefetch   Update   Rsvd     Lock     Safe    Valid │
       │ 20:39              Enable     Enable            Enable   DMA           │
       │ 20 bits   5 bits   1 bit      1 bit    2 bits   1 bit    1 bit   1 bit │
       └────────────────────────────────────────────────────────────────────────┘

the virtual index field is filled with the results of the LCI (Load Coherence Index) instruction. the 8 bits used for the virtual index are bits 12:19 of the value returned by LCI. that's the field update, literally, no extra drama 🌈

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🔥 SEE ALSO 🔥

Kernel file ./drivers/parisc/ccio-dma.c is the source-file bestie for this whole crew. also go peek at:

• ccio_alloc_range(9)
• ccio_free_range(9)
• ccio_clear_io_tlb(9)
• ccio_mark_invalid(9)
• ccio_dma_supported(9)
• ccio_map_single(9)
• ccio_unmap_phys(9)
• ccio_alloc(9)
• ccio_free(9)
• ccio_map_sg(9)
• ccio_unmap_sg(9)
• ccio_find_ioc(9)
• ccio_get_iommu(9)
• ccio_ioc_init(9)
• ccio_probe(9)
• ccio_init(9)

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xoxo, bestie 💖 — source/version: ./drivers/parisc, date: October 2026, page: ccio_io_pdir_entry(9). periodt. 💅