acpi_dev_present(9)

📦 version 7.3.1, in nixpkgs unstable

💅 acpi_dev_present(9) — bestie's guide to the Kernel API Manual ✨

okay so real talk, this is a page from the Kernel API Manual and it's about acpi_dev_present(9), which lowkey does exactly what it says on the tin 🫶

✨ NAME ✨

acpi_dev_present — detect that a given ACPI device is present 👀✨

🌸 SYNOPSIS 🌸

bool acpi_dev_present (const char *hid , const char *uid , s64 hrv );

like, that's the whole vibe. three args, one bool, no drama 💅

🎀 ARGUMENTS 🎀

  • hid — the Hardware ID of the device. the main character identifier fr 🔥
  • uid — the Unique ID of the device. if you don't wanna check _UID, just pass NULL and keep it moving 🙈
  • hrv — the Hardware Revision of the device. don't care about _HRV? pass -1 and slay 💀

🦋 DESCRIPTION 🦋

so here's the tea: it returns true if a matching device was present at the moment of invocation. at the moment. like right then. ⏰

⚠️ heads up bestie: if the device is pluggable, it may have disappeared since then. it's giving "you blinked and it was gone" 😭 do NOT treat that true as a forever-promise.

also, this is not the same as acpi_dev_found — this one actually checks the status of the device. so for devices that are present in the DSDT but are disabled (their _STA callback returns 0), this function will return false. no cap, that's a whole different vibe check 💅

for this function to work, acpi_bus_scan must have been executed, which happens in the subsys_initcall subsection. so:

  • 🚫 do not call from a subsys_initcall or earlier (use acpi_get_devices instead, king behavior 👑)
  • ✅ calling from module_init is totally fine — it's synonymous with device_initcall, iykyk

🌈 SEE ALSO 🌈

the kernel file ./drivers/acpi/utils.c and honestly a whole friend group of functions:

and that's the whole page, bestie 🧚 no crumbs left, every single reference accounted for, periodt 💜

sign-off time 🎀 this one lives in ./drivers/acpi, dated October 2026 — go check the device, have fun, don't call it too early, ily 💖✨

📦 where this page comes from