core_param(9)

📦 version 7.3.1, in nixpkgs unstable

💖 core_param(9) 💖

okay so bestie, welcome to the Kernel API Manual — yes this is a real one, section 9, and it's giving "small function, big historical importance" energy. Let's get into it ✨

🌸 NAME 🌸

core_param — define a historical core kernel parameter.

(yes, historical, she's been here a minute 🎀)

🦋 SYNOPSIS 🦋

core_param (name , var , type , perm );

🌈 ARGUMENTS 🌈

  • name — the name of the cmdline and sysfs parameter. fun fact: it's often the exact same thing as var 👀
  • var — the variable itself. the actual variable. the main character 💅
  • type — the type of the parameter.
  • perm — visibility in sysfs. i.e. who gets to see her in /sys 🫶

⭐ DESCRIPTION ⭐

so here's the tea ☕ core_param is just like module_param, except for two very important things:

  • it cannot be modular — nope, no module energy here, she's built in, periodt 💀
  • it doesn't add a prefix (such as printk.) — no little name tag, she's just out there raw 😭

and why? because this is for compatibility with __setup, and honestly it makes sense — truly core parameters aren't tied to the particular file they're in. they're core. they're everywhere. they're not defined by which .c file they happened to be typed into 👑

ngl that's kind of iconic of them.

🔥 SEE ALSO 🔥

Kernel file ./include/linux/moduleparam.h — go read it, iykwinkw 👀 — plus the whole friend group:

like. that's a lot of cousins at the family reunion 🧚

💖 cute little sign-off: this page lives under ./include/linux, it's dated October 2026, and you just read core_param(9). slay, go define some core params, and remember — no prefix, no modules, no problem 🎀✨
📦 where this page comes from