cppc_get_perf_limited(9)

💅 cppc_get_perf_limited(9) 💅

okay so bestie, welcome to the Kernel API Manual — yes that's the manual name, we're fancy now 🎀 — and today's main character is cppc_get_perf_limited, which lowkey just reads a register for you. Let's get into it ✨

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✨ SYNOPSIS ✨

int cppc_get_perf_limited (int cpu , u64 *perf_limited );

that's the whole vibe. two args, one int back. slay 🫶

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🌸 ARGUMENTS 🌸

• cpu — the CPU you're pulling the Performance Limited register from. like, which CPU. you gotta pick one, girl, we're not mind readers 💅
• perf_limited — a pointer where the Performance Limited value gets stashed. bring your own storage, we just fill it in 🎀

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🦋 DESCRIPTION 🦋

so the value that comes back holds sticky status bits — and by sticky I mean they hang around, they don't just evaporate — and those bits are telling you about performance limitations imposed by the platform. that's the whole plot. no cap 🧚

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🔥 RETURN 🔥

• 0 — success, we ate 💖
• -EIO — failure, it's giving pain 😭
• -EOPNOTSUPP — not supported. she's just not available rn 🙈

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👑 SEE ALSO 👑

okay this list is long but every single one of these deserves their moment, periodt:

• Kernel file ./drivers/acpi/cppc_acpi.c
• acpi_get_psd_map(9)
• cpc_ffh_supported(9)
• cpc_supported_by_cpu(9)
• pcc_data_alloc(9)
• acpi_cppc_processor_probe(9)
• acpi_cppc_processor_exit(9)
• cpc_read_ffh(9)
• cpc_read_ffh_fb_ctrs(9)
• cpc_write_ffh(9)
• cppc_get_desired_perf(9)
• cppc_get_nominal_perf(9)
• cppc_get_highest_perf(9)
• cppc_get_epp_perf(9)
• cppc_get_perf_caps(9)
• cppc_perf_ctrs_in_pcc_cpu(9)
• cppc_perf_ctrs_in_pcc(9)
• cppc_get_perf_ctrs(9)
• cppc_set_epp(9)
• cppc_get_auto_act_window(9)
• cppc_set_auto_act_window(9)
• cppc_get_auto_sel(9)
• cppc_set_auto_sel(9)
• cppc_set_enable(9)
• cppc_get_perf(9)
• cppc_set_perf(9)
• cppc_set_perf_limited(9)
• cppc_get_transition_latency(9)

like… the whole friend group showed up 🌈💜

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ngl bestie, if you get -EOPNOTSUPP it's genuinely not you, it's the platform 💀

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and that's the page!! sourced straight from ./drivers/acpi, dated October 2026 ⭐ mwah, ilysm, go read some registers 💅💖