ACPI_VIDEO(4)

📦 version 15.1, in freebsd 14.5, freebsd 15.1, nixpkgs unstable

🎀 acpi_video — ACPI Video Extensions driver 🎀

okay bestie, this is the acpi_video(4) page from the Kernel Interfaces Manual, and we're gonna get you comfy with it. no cap, it's giving “my laptop screen and brightness finally make sense” energy. ✨

🌸 NAME 🌸

acpi_video — the ACPI Video Extensions driver. that's the name, and that's the whole job. literally the driver for this ACPI video situation. 💅

🦋 SYNOPSIS 🦋

device acpi_video

✨ DESCRIPTION ✨

okay so this driver uses the ACPI Video Extensions to control display switching and backlight brightness. that's the whole vibe: switch displays, adjust brightness. 🔥

whether you actually get the sysctl(8) variables at all depends on the functions offered by the host's ACPI implementation. so if some knobs are missing, it's not you — it's the ACPI implementation doing its own thing. 🫶

🎀 SYSCTL VARIABLES 🎀

here are the sysctls that are currently implemented, with ⟨device⟩ standing in for crt, lcd, or tv:

  • hw.acpi.video.⟨device⟩.active — what the output device is doing rn. 👀
  • hw.acpi.video.⟨device⟩.levels — the list of brightness levels this thing supports. the official brightness menu, iykyk. 🌈
  • hw.acpi.video.⟨device⟩.brightness — where the brightness is at rn. yes, the actual brightness. ☀️
  • hw.acpi.video.⟨device⟩.fullpower — the brightness preset for full power mode. main character full-power brightness. 👑
  • hw.acpi.video.⟨device⟩.economy — the brightness preset for economy mode. low-power era, but make it cute. 🍓

defaults for these variables can be set in sysctl.conf(5), which is parsed at boot-time. so you can set your faves and they'll show up when the system boots. 💖

💀 COMPATIBILITY 💀

vibe check: for acpi_video to attach correctly, it should be loaded after any of the DRM kernel modules. no skipping the line, bestie. 🚦

you can achieve this by setting the correct order in rc.conf(5) using the kld_list directive. that's the move. periodt. 💅

🌟 SEE ALSO 🌟

🦋 HISTORY 🦋

the acpi_video driver first appeared in FreeBSD 5.3. vintage, but make it functional. ✨

👑 AUTHORS 👑

the acpi_video driver was written by Taku YAMAMOTO <taku@cent.saitama-u.ac.jp>. this manual page was written by Mark Santcroos <marks@ripe.net>. icons only. 🫶

🙈 BUGS 🙈

some systems handle output switching exclusively through SMM, even when they export the proper info via ACPI. in that case, you gotta use the proper hotkeys or the OEM driver (for example, acpi_toshiba(4)) instead. so if the ACPI path isn't switching outputs, don't force it — use the hotkeys or the OEM driver. 💀

and that's the page! it's from Debian, dated November 8, 2004, and the manual name is ACPI_VIDEO(4) — mwah, bye bestie! 💖🎀✨

📦 where this page comes from