iommufd_access_rw(9)

📦 version 7.3.1, in nixpkgs unstable

💅 iommufd_access_rw — read or write data under the iova

okay so bestie, welcome to the Kernel API Manual ✨ this one is literally iommufd_access_rw, and it's giving "copy bytes to/from an IOVA" energy. it's a function, not a command — no cap. let's get into it 🎀

🌸 SYNOPSIS 🌸

int iommufd_access_rw (struct iommufd_access *access , unsigned long
iova , void *data , size_t length , unsigned int flags );

like... look at her. five params. returns an int. iconic behavior honestly 👑

✨ ARGUMENTS ✨

  • access — the IOAS access you're acting on. this is your main character. everything happens through her 🫶
  • iova — the starting IOVA. where the party begins 💖
  • data — the kernel buffer you're copying to/from. the actual payload, the substance, the vibe 🌸
  • length — how many bytes we're accessing. the size of the moment, fr fr
  • flags — IOMMUFD_ACCESS_RW_* flags. literally whatever flags you've got, they go here 🦋

🦋 DESCRIPTION 🦋

so what does she do? she copies kernel-to/from data into the range that iova/length gives you. simple. clean. the range is the range 💅

and here's the lowkey cool part: if flags indicates IOMMUFD_ACCESS_RW_KTHREAD, then a large copy can get optimized — it gets changed into copy_to/from_user instead. the way that just... works. efficiency slay 🔥

ngl this is just the copy helper — she's not out here doing the pinning or the notifying, she moves your bytes and that's it. know your lane bestie 😌

🎀 SEE ALSO 🎀

the whole friend group, in the kernel file ./drivers/iommu/iommufd/device.c:

and that's the whole page, bestie 💖 shoutout to the source at ./drivers/iommu/iommufd in the Kernel API Manual, dated October 2026 — go forth and copy your bytes responsibly, ily, mwah 😭🫶💜

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