iommu_dma_init_domain(9)

💅 iommu_dma_init_domain(9) — straight out of the Kernel API Manual

okay so bestie, sit down, hydrate, and let me tell you about the single most setup-era function in the IOMMU world. it's giving "let me get you situated before the real magic happens" ✨

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✨ NAME ✨

iommu_dma_init_domain — the girl whose whole job is initialising a DMA mapping domain 🎀

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🎀 SYNOPSIS 🎀

int iommu_dma_init_domain (struct iommu_domain *domain , struct device
*dev );

like, that's the whole entrance exam. two args, one int back. we love a low-maintenance signature 🫶

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🦋 ARGUMENTS 🦋

• domain — the IOMMU domain, and no she is not new here, she was previously prepared by iommu_get_dma_cookie 🍓 like she's already been through hair and makeup, you're just doing the final fit check.
• dev — the device this domain is being initialised for. that's her plus-one. her reason for being. her main character 🫶

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🌸 DESCRIPTION 🌸

okay so here's the tea ☕ — if the geometry and the dma_range_map both include address 0, then we reserve that page so that it stays a guaranteed invalid IOVA. no cap, address 0 is not invited to the mapping party, she's literally not on the list 💀

and the reinit situation? it's fine. honestly it's fine. it is safe to reinitialise a domain — glow-ups are allowed, rebrands are allowed, we don't gatekeep 🌈

but. if your change could make any prior IOVAs invalid, it will fail. periodt. that's the one thing we do not do here 🙈 so double-check before you go rearranging furniture, bestie.

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🔥 SEE ALSO 🔥

all the siblings, the whole friend group, the entire group chat 👑:

• kernel file ./drivers/iommu/dma-iommu.c (yes, that's where she lives 🏡)
• iommu_get_dma_cookie(9)
• iommu_get_msi_cookie(9)
• iommu_put_dma_cookie(9)
• iommu_put_msi_cookie(9)
• iommu_dma_get_resv_regions(9)
• iommu_dma_init_options(9)
• dma_info_to_prot(9)
• dma_iova_try_alloc(9)
• dma_iova_free(9)
• dma_iova_link(9)
• dma_iova_sync(9)
• dma_iova_unlink(9)
• dma_iova_destroy(9)

like, read them all. iykyk 💜

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and that's the page, bestie 💖 this whole thing lives over in ./drivers/iommu, it's dated October 2026, and it's brought to you by the Kernel API Manual — slay, bye, go init your domains responsibly 🌸🦋✨