ACPI_VIDEO(4)

📦 version 12.2, in debian bookworm, debian trixie, ubuntu jammy, ubuntu noble, ubuntu questing, ubuntu resolute, ubuntu stonking

💖 ACPI_VIDEO(4) 💖

okay bestie, welcome to the Kernel Interfaces Manual page for acpi_video — yes, a whole section 4 manual, we're being ✨official✨ today.

✨ NAME ✨

acpi_video — the ACPI Video Extensions driver, aka the thing that handles your screen switching and your brightness sliders 🎀

🌸 SYNOPSIS 🌸

device acpi_video

that's it. that's the whole synopsis. iconic, honestly 💅

🦋 DESCRIPTION 🦋

so this driver uses the ACPI Video Extensions to control two very main-character things:

  • display switching 🔀
  • backlight brightness ☀️

but — and this is the important part, no cap — whether you actually get the sysctl(8) variables depends entirely on what functions your host's ACPI implementation decided to offer. so like. it's giving "results may vary" energy 🙈. your laptop's ACPI said what it said.

💅 SYSCTL VARIABLES 💅

here's what's currently implemented, and where you see ⟨device⟩, that's your placeholder for one of these three queens: crt, lcd, or tv 👑

  • hw.acpi.video.⟨device⟩.active — the current state of the output device. is it on? is it off? vibe check 🔍
  • hw.acpi.video.⟨device⟩.levels — a whole list of the brightness levels that are supported. the menu, basically 🍓
  • hw.acpi.video.⟨device⟩.brightness — the current brightness level of the device. right now. as we speak ✨
  • hw.acpi.video.⟨device⟩.fullpower — the preset brightness level that gets used in full power mode 🔥
  • hw.acpi.video.⟨device⟩.economy — the preset brightness level that gets used in economy mode 🌱 (saving that battery, we love to see it)
💡 and listen — the defaults for all of these variables can be set in sysctl.conf(5), which gets parsed at boot-time. so set them once, forget them, slay 🫶

🌈 SEE ALSO 🌈

go read them, they're the supporting cast and they ate 💜

📜 HISTORY 📜

the acpi_video driver first appeared in FreeBSD 5.3. a true veteran, a legacy icon, born to be on this list ⭐

👑 AUTHORS 👑

the acpi_video driver was written by Taku YAMAMOTO <taku@cent.saitama-u.ac.jp> — thank you for your service, king 🫡

and this manual page was written by Mark Santcroos <marks@ripe.net> — the wordsmith, the pen, the moment 🎀

💀 BUGS 💀

okay so here's the tea, and it's a little annoying: some systems only do output switching via SMM, even though they do export the proper information via ACPI. like, you gave us the info and then you don't even use it?? make it make sense 😭

on systems like that, you have to use the proper hotkeys instead, or the OEM driver — for example, acpi_toshiba(4) — and there is literally no other option. it's not a vibe, it's a workaround 🙃

and that's the whole page bestie!! this one came from the Debian crew, dated November 8, 2004 — yeah, 2004, we were all babies 😭 — and it lives at ACPI_VIDEO(4) in the Kernel Interfaces Manual. mwah, go forth and manage your brightness 💖✨🎀

📦 where this page comes from