check_power_actors(9)

📦 version 7.3.1, in nixpkgs unstable

💅 check_power_actors(9) — Kernel API Manual, bestie edition

okay so real talk, this is a page from the Kernel API Manual and it's called check_power_actors(9). yes the (9) is part of the name, it's giving very section-nine, very kernel-internals. we move.

🌸 NAME 🌸

check_power_actors — literally just goes around checking all your cooling devices and warns you when they're not power actors. that's it. that's the whole gig. 🫶

✨ SYNOPSIS ✨

int check_power_actors (struct thermal_zone_device *tz , struct
       power_allocator_params *params );

like yeah, two args, returns an int. classic. 💅

🎀 ARGUMENTS 🎀

  • tz — the thermal zone we're operating on. this is the main character of the whole function ngl. 🔥
  • params — the power allocator's own private data. it's private, it's personal, don't ask questions. 🙈

🦋 DESCRIPTION 🦋

so the vibe here is: check_power_actors checks every single cooling device in tz, and every time it finds one that's missing the power actor API, it warns. not silently fails, not throws a tantrum — just a nice loud warning. 🗣️

and like, those warnings are actually useful, okay? they're there to help you investigate the issue, which could literally be something like a device just not having an Energy Model. so when you see the warning, that's your sign to go look. iykyk. 🔍

then the return value, which is the part everyone actually cares about:

  • if all of the cooling devices currently attached to tz implement the power actor API → it returns the number of them. and yes, that number can legitimately be 0, because some cooling devices might get attached later. zero is a valid slay. 🎉
  • otherwise → it returns -EINVAL. not great, not terrible, but definitely a "go fix your devices" moment. 💀
fr fr do not sleep on the -EINVAL here — it means at least one attached cooling device is not a power actor and the warning already told you about it.

🌈 SEE ALSO 🌈

Kernel file ./drivers/thermal/gov_power_allocator.c, plus all these besties who live in the same neighborhood:

and that's the whole page! 🧚 this one lives in ./drivers/thermal and it's dated October 2026 — so like, future-coded of it. go check those power actors, bestie, and remember: warn loudly, return honestly, periodt. 👑💖

📦 where this page comes from