acpi_evaluate_dsm(9)

💅 acpi_evaluate_dsm — the kernel API manual, bestie edition ✨

okay so real talk, this is the man page for acpi_evaluate_dsm from the Kernel API Manual, and yes i'm gonna walk you through the whole thing because you deserve to understand it 🫶

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✨ NAME ✨

acpi_evaluate_dsm — literally just "evaluate device's _DSM method" 💖 that's the whole vibe. it calls the thing. that's it. iconic behavior honestly.

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🌸 SYNOPSIS 🌸

union acpi_object * acpi_evaluate_dsm (acpi_handle handle , const guid_t
*guid , u64 rev , u64 func , union acpi_object *argv4 );

look at that signature. five params, one return, zero notes. she's serving function prototype realness 👑

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🎀 ARGUMENTS 🎀

every single one, no skips, let's gooo:

• handle — an ACPI device handle. it's the device you're talking to, bestie 🦋
• guid — the GUID of the requested functions. should be 16 bytes, no cap. if you mess that up that's on you 🙈
• rev — the revision number of the requested function. u64, keep up 💅
• func — the requested function number. also u64. also important ✨
• argv4 — the function-specific parameter. yes it's named argv4. yes that's a little C-coded. we move 🧚

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💜 DESCRIPTION 💜

okay so what this does: it evaluates the device's _DSM method using the GUID you passed, the revision id, and the function number. simple as that 💖

big important thing though — the caller needs to free the returned object. like, YOU. you free it. don't just leak it into the void, that's not the vibe 😭 main character energy means cleaning up after yourself.

and now the messy part, the tea ☕: ACPI defines that the fourth parameter for _DSM should be a package. but some old BIOSes out here do expect a buffer, or an integer, etc. so yeah. legacy firmware being legacy firmware 💀 not us fixing it, just us reporting it.

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🔥 SEE ALSO 🔥

all the siblings, cousins, and adjacent icons — kernel file ./drivers/acpi/utils.c plus:

• acpi_handle_list_equal(9)
• acpi_handle_list_replace(9)
• acpi_handle_list_free(9)
• acpi_device_dep(9)
• acpi_evaluate_ost(9)
• acpi_handle_path(9)
• acpi_handle_printk(9)
• __acpi_handle_debug(9)
• acpi_evaluation_failure_warn(9)
• acpi_has_method(9)
• acpi_evaluate_ej0(9)
• acpi_evaluate_lck(9)
• acpi_evaluate_reg(9)
• acpi_check_dsm(9)
• acpi_dev_uid_to_integer(9)
• acpi_dev_found(9)
• acpi_dev_present(9)
• acpi_dev_get_next_match_dev(9)
• acpi_dev_get_first_match_dev(9)
• acpi_reduced_hardware(9)
• acpi_dev_is_video_device(9)
• acpi_match_platform_list(9)

go read them. all of them. i'll wait 🍓

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and that's the page!! final sign-off: this came out of ./drivers/acpi, dated October 2026, and the manual itself is acpi_evaluate_dsm(9) — so if you need to cite it in your commit message, you're welcome bestie 💅✨ slay, go free your union acpi_object *, and have a gorgeous day 🎀🦋🌈