hp_wmi_perform_query(9)

📦 version 7.3.1, in nixpkgs unstable

💻 hp_wmi_perform_query(9) — the kernel API manpage, but make it make sense ✨

Okay bestie, so this one's a Kernel API Manual page (yes, man 9 girlies rise 💅) for hp_wmi_perform_query. It's the HP WMI ✨query-performing✨ function, and it's lowkey the whole plumbing behind how the kernel talks WMI queries to your HP box. Let's get into it 🫶

📛 NAME

hp_wmi_perform_query —

...and that's literally it. The manpage gives the function name and then just a dash, no description, ndthing. Not me leaving it blank on purpose — that's genuinely what the original says, fr fr 😭 So just know: it's hp_wmi_perform_query, and the name section is giving minimalist icon energy. Periodt.

📜 SYNOPSIS

int hp_wmi_perform_query (int query , enum hp_wmi_command command , void
*buffer , u32 insize , u32 outsize );

It returns an int, bestie. That's the main character of the whole page. 🌟

🎀 ARGUMENTS

  • query — the commandtype, and it's an enum hp_wmi_commandtype 👑 that's your which query am I even doing argument, okay.
  • command — the command, type enum hp_wmi_command 💫 like, the actual verb of the operation.
  • buffer — the buffer used as input and/or output 🔁 yes, and/or, it does both jobs, multi-talented queen.
  • insize — size of the input buffer, u32, don't forget her 📏
  • outsize — size of the output buffer, also u32, also important 🧚

🔍 DESCRIPTION

Okay so here's the return-value tea, and it's a whole little flowchart ☕ Let's break it down because the original runs it all together and we're better than that:

  • it returns zero on success ✅ iconic, no notes
  • an HP WMI query specific error code — and heads up: that one is positive ⚠️ so like, don't assume "non-zero = negative errno", okay?
  • -EINVAL if the query was not successful at all 💀
  • -EINVAL if the output buffer size exceeds buffersize 🙈 yes, same error code for two different situations, that's just how it is, I don't make the rules
⚠️ Warning-ish vibe: two completely different failure modes both hand you back -EINVAL, so if you're debugging, don't assume it's only one thing. That's real, that's in the original, write it down ✍️

🧠 NOTE

The buffersize must at least be the maximum of the input and output size — like, the bigger of the two, not the sum, not the input, the max 🔥 Write that on your forehead.

Real example from the page: the Battery info query is defined to have 1 byte input and 128 byte output. So the caller would do:

buffer = kzalloc(128, GFP_KERNEL);
ret = hp_wmi_perform_query(HPWMI_BATTERY_QUERY, HPWMI_READ, buffer, 1, 128);

See how 128 is the max of 1 and 128? That's the whole bit 💡 obsessed with the consistency honestly.

👀 SEE ALSO

Go read those next, iykyk 💜

🌈 cute sign-off

That's the whole page bestie 🎀 — brought to you by source ./drivers/platform/x86/hp/hp-b..., dated October 2026, and yeah, the footer is the same hp_wmi_perform_query(9) as the top because symmetry slays 💅✨ Go forth and pass the right outsize, ily, bye 🫶

📦 where this page comes from