intel_idle_cst_usable(9)

✨ intel_idle_cst_usable(9) ✨

okay so this is a page from the Kernel API Manual (yes, the kernel has lore fr) and today's main character is intel_idle_cst_usable 💅 buckle up bestie, it's a short one but it's iconic.

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🌸 NAME 🌸

intel_idle_cst_usable — the little function that checks whether the _CST info is even usable 💖

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🎀 SYNOPSIS 🎀

bool intel_idle_cst_usable (void );

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🦋 ARGUMENTS 🦋

• void — no arguments. zero. nada. she takes nothing and she gives you a bool, periodt ✨

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💜 DESCRIPTION 💜

So here's the vibe check 👑: this function checks whether all of the C-states listed by _CST inside the max_cstate range are ACPI_CSTATE_FFH. And what does that mean, you ask? it means those states should be entered via MWAIT. that's it, that's the whole function. no cap 🫶

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🌈 SEE ALSO 🌈

like the whole friend group shows up here, lowkey:

• ./drivers/idle/intel_idle.c — the kernel file she lives in 🏠
• intel_idle(9)
• intel_idle_s2idle(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)

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k that's the whole page bestie, she's short but she ate 💅

and a lil sign-off before you go 🍓: this one ships from ./drivers/idle, dated October 2026, and honestly the date being in the future is giving time-travel main character energy 😭💀 slay.