copy_from_iter_toio(9)

💅 copy_from_iter_toio (kernel API manual, section 9) ✨

okay so bestie, welcome to the Kernel API Manual — section 9, the good section, the kernel-internals section 🎀 — and today's main character is copy_from_iter_toio, which is literally just "move bytes from an iov_iter into mmio-space." That's it. That's the whole vibe. slay.

---

🌸 NAME 🌸

copy_from_iter_toio — copy data from iov_iter to mmio-space 💫

---

✨ SYNOPSIS ✨

size_t copy_from_iter_toio (void __iomem *dst , size_t count , struct
       iov_iter *src );

look at her. three args, one size_t coming back. confident. no notes. 👑

---

🫶 ARGUMENTS 🫶

• dst — the destination pointer, and she lives on mmio-space 💅 (yes, the __iomem one, respect her)
• count — the data size to copy, measured in bytes 🧮
• src — the source iov_iter, aka where the bytes are coming from 🦋

---

💖 DESCRIPTION 💖

Copies the data from iov_iter to mmio-space. 🎀

that's the whole thing. bytes go in on the src side, bytes come out on the mmio side, and honestly? iconic behaviour. not me being obsessed with a copy function 😭

---

⭐ RETURN ⭐

number of bytes to be copied 🔥

---

🌈 SEE ALSO 🌈

• Kernel file ./sound/core/memory.c — the home base, the origin story 🏠
• copy_to_user_fromio(9) 🫶
• copy_to_iter_fromio(9) ✨
• copy_from_user_toio(9) 💜

like, she's got a whole friend group. iykyk. 🦋

---

ngl bestie, this one genuinely is just a copy — no tricks, no gotchas hiding in here 🙈

---

mwah 💋 that's the page! brought to you by the fine folks over in ./sound/core, dated October 2026 — you're welcome, go copy some bytes responsibly, ily 🫶✨🎀