iio_backend_ext_info_get(9)

📦 version 7.3.1, in nixpkgs unstable

💅 iio_backend_ext_info_get — a Kernel API Manual moment (section 9, bestie)

okay so this is the iio_backend_ext_info_get(9) page, straight out of the Kernel API Manual, and honestly? it's giving "small helper, big responsibilities." let's get into it 🎀

✨ NAME ✨

iio_backend_ext_info_get — the IIO ext_info read callback. yes that's the whole name. she's concise. we respect it. 👑

✨ SYNOPSIS ✨

ssize_t iio_backend_ext_info_get (struct iio_dev *indio_dev , uintptr_t
private , const struct iio_chan_spec *chan , char *buf );

that's the whole signature, no cap. four args, one ssize_t return, and a whole lot of purpose 🦋

✨ ARGUMENTS ✨

  • indio_dev — the IIO device themselves. main character energy, obviously 💖
  • private — data that's private to the driver. secrets. we love that for them 🙈
  • chan — the IIO channel. the vibe check happens here ✨
  • buf — the buffer where we place the attribute data. put it there. gently 🎀

✨ DESCRIPTION ✨

okay so here's the tea ☕ — this helper is intended to be used by backends that extend an IIO channel with extended info, and the way they do that is through iio_backend_extend_chan_spec.

and here's the part where it gets a little spicy 🔥: in that case, backends are not supposed to give their own callbacks — because (and this is the important bit) they would not have a way to get the backend from indio_dev. like, the pointer just isn't there, bestie. it's not a skill issue, it's a design issue. 😭

so instead of backends doing their own thing, this helper is the getter. she gets. periodt. 💅

✨ RETURN ✨

  • number of bytes written to buf (slay, it tells you how much it wrote) 🌸
  • negative error number on failure (ngl, if you see a negative number, something went wrong — do not ignore it, i'm literally begging 😭)

✨ SEE ALSO ✨

the kernel file, in all her glory:

./drivers/iio/industrialio-backend.c

and now the full friend group, everyone invited to the group chat 🫶:

bestie reminder: that double-underscore one is __devm_iio_backend_get_from_fwnode_lookup(9) — two underscores, don't @ me, just copy it exactly 💀

and that's the whole page!! 🧚 from ./drivers/iio, dated October 2026 — ty for reading my manual page essay, ily, go read the kernel source, mwah 💜💖✨

📦 where this page comes from