cdev_add(9)

📦 version 7.3.1, in nixpkgs unstable

💅 cdev_add(9) — the "make your char device live" moment ✨

okay bestie, welcome to cdev_add(9), from the Kernel API Manual. This is the glow-up ritual where your char device officially joins the system. Let's go 🫶

🌸 NAME 🌸

cdev_add — add a char device to the system

Literally what it says. Your device gets added. Slay.

✨ SYNOPSIS ✨

int cdev_add (struct cdev *p , dev_t dev , unsigned count );

That's the whole vibe. Returns an int, takes three things. Iconic signature, no notes 💅

🎀 ARGUMENTS 🎀

  • p — the cdev structure for the device. This is your main character — the struct that represents the thing you're adding.
  • dev — the first device number for which this device is responsible. First one! The rest follow after it bestie.
  • count — the number of consecutive minor numbers corresponding to this device. Like, how many minors in a row belong to you.

🦋 DESCRIPTION 🦋

So cdev_add adds the device represented by p to the system, and — this is the key part — it makes it live immediately. No waiting, no queued-up later moment, no "pending approval" energy. The second it's added, it's out there living its life 🔥

And if it fails? A negative error code is returned. That's your signal, bestie — negative means something went wrong, so go check it 😭

💜 SEE ALSO 💜

Kernel file ./fs/char_dev.c — and the whole friend group:

iykyk 👑

ngl this one is short but it does exactly what it says: add the char device, make it live right away, and hand back a negative error code if it didn't work. Don't overthink it, bestie 💖

mwah 💋 that's the page — source lives in ./fs, and this beauty is dated October 2026, signed off as cdev_add(9). periodt 🎀✨

📦 where this page comes from