subsys_system_register(9)

📦 version 7.3.1, in nixpkgs unstable

🎀 subsys_system_register(9) 🎀

okay bestie, welcome to the Kernel API Manual — today's episode: subsys_system_register, aka the function that registers a subsystem at /sys/devices/system/. yes it's a whole vibe. let's get into it ✨

✨ NAME ✨

subsys_system_register — register a subsystem at /sys/devices/system/ 💅

🌸 SYNOPSIS 🌸

int subsys_system_register (const struct bus_type *subsys , const struct
       attribute_group **groups );

like, that's the whole signature. no cap. 🫶

🦋 ARGUMENTS 🦋

  • subsys — the system subsystem itself. yep, that's the whole description, it's giving minimalism 💀
  • groups — the default attributes for the root device 🎀

💖 DESCRIPTION 💖

so here's the tea ☕ — every 'system' subsystem gets a root device at /sys/devices/system/<name>, and <name> is literally just the name of the subsystem. iconic. that root device is allowed to carry subsystem-wide attributes.

all the registered devices live below this single root device 👑, and they're named after the subsystem with a simple enumeration number tacked on the end. and get this — the registered devices are not explicitly named. the only thing you need to set is 'id' in the device. that's it. that's the whole assignment bestie 🍓

⚠️ okay this is the important part, pay attention ⚠️ Do not use this interface for anything new. it exists purely for compatibility with bad ideas only. fr fr, don't do it 😭 new subsystems should use plain subsystems instead. and if you gotta add subsystem-wide attributes, add them to the subsystem directory itself — not to some fake root-device you created and dropped into /sys/devices/system/<name>. we do not stan fake root devices in this house 🙈

🔥 SEE ALSO 🔥

also check out the kernel file ./drivers/base/bus.c and honestly the whole friend group:

that's the whole page bestie, you ate that 💅✨

this cutie lives over in ./drivers/base, dropped October 2026 — mwah, bye 🎀🦋💜

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