intel_idle_s2idle(9)

💤 intel_idle_s2idle — Kernel API Manual, section 9, bestie 💤

okay so picture this: it's a kernel API manual page, section 9, and the function we're stanning today is intel_idle_s2idle. That's the whole title, no notes, she's literally the main character. 🫶

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✨ NAME ✨

intel_idle_s2idle — ngl this one's entire job description is: ask the processor to enter the given idle state. That's it. That's the vibe check. 💅

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🌸 SYNOPSIS 🌸

__cpuidle int intel_idle_s2idle (struct cpuidle_device *dev , struct
       cpuidle_driver *drv , int index );

look at her. __cpuidle, returns int, takes three little guys. iconic signature, no cap. ✨

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🎀 ARGUMENTS 🎀

• dev — the cpuidle device of the target CPU. like, which CPU are we putting to sleep, bestie? this one. 🦋
• drv — the cpuidle driver (and lowkey it's assumed to point to intel_idle_driver, so don't come at her with some random driver, okay?). 💀
• index — the target idle state index. your girl's destination on the sleepy-time map. 🗺️

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🧚 DESCRIPTION 🧚

so the way this works is: she uses the MWAIT instruction to notify the processor that the CPU represented by dev is idle, and that it can try to enter the idle state corresponding to index. literally just a polite little "hey king, she's free, you can rest now." 😴✨

and here's the part where it gets interesting — she gets invoked as a suspend-to-idle callback routine with:

• frozen user space ❄️
• frozen scheduler tick 🧊
• suspended scheduler clock ⏰

…on the target CPU. yes, all of that, at the same time. it's giving deep-freeze deluxe. no cap. 💜

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🔥 SEE ALSO 🔥

the whole group chat showed up, fr fr. Kernel file ./drivers/idle/intel_idle.c, plus:

• intel_idle(9)
• intel_idle_cst_usable(9)
• ivt_idle_state_table_update(9)
• irtl_2_usec(9)
• bxt_idle_state_table_update(9)
• sklh_idle_state_table_update(9)
• skx_is_pc6_disabled(9)
• skx_idle_state_table_update(9)
• spr_idle_state_table_update(9)
• drop_pc6_redundant_cstates(9)
• byt_cht_auto_demotion_disable(9)
• intel_idle_cpuidle_driver_init(9)
• intel_idle_cpu_init(9)
• intel_idle_cpuidle_devices_uninit(9)
• validate_cmdline_cstate(9)
• cmdline_table_adjust(9)

like, she's popular. she has connections. 👑

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💖 and that's the page!! source lives at ./drivers/idle, dated October 2026 — periodt, go take a nap, you've earned it 😭💤 🌈