cache_setup_acpi(9)

💅 cache_setup_acpi(9) — bestie edition 💅

okay so this is cache_setup_acpi(9) from the Kernel API Manual, and it's giving “ACPI said let me fix the CPU cache topology” energy. slay. Let's get into it. ✨

🌸 NAME 🌸

cache_setup_acpi — Override CPU cache topology with data from the PPTT. 💖

🌟 SYNOPSIS 🌟

int cache_setup_acpi (unsigned int cpu );

🎀 ARGUMENTS 🎀

• cpu — the Kernel logical CPU number. That's the CPU you're pointing at, no cap. 👑

🦋 DESCRIPTION 🦋

Okay so here's the tea: cache_setup_acpi updates the global cache info provided by cpu_get_cacheinfo when there are valid properties in the acpi_pptt_cache nodes.

Important vibe check: a successful parse may not result in any updates if none of the cache levels have any valid flags set. So it can literally succeed and still be a no-op — that's not a bug, bestie, that's just how it is. 😌

Also: a unique value is associated with each known CPU cache entry. That unique value can be used to determine whether caches are shared between CPUs. iykyk 🔥

🔥 RETURN 🔥

• -ENOENT on failure to find table. 😭
• 0 on success. 💖

👑 SEE ALSO 👑

Kernel file ./drivers/acpi/pptt.c has the whole friend group:

• acpi_pptt_walk_cache(9)
• acpi_count_levels(9)
• acpi_pptt_leaf_node(9)
• acpi_find_processor_node(9)
• update_cache_properties(9)
• topology_get_acpi_cpu_tag(9)
• check_acpi_cpu_flag(9)
• acpi_get_cache_info(9)
• acpi_pptt_cpu_is_thread(9)
• find_acpi_cpu_topology(9)
• find_acpi_cpu_topology_package(9)
• find_acpi_cpu_topology_cluster(9)
• find_acpi_cpu_topology_hetero_id(9)
• acpi_pptt_get_child_cpus(9)
• acpi_pptt_get_cpus_from_container(9)
• find_acpi_cache_level_from_id(9)
• acpi_pptt_get_cpumask_from_cache_id(9)

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mwah 💋 — signed, sealed, delivered by ./drivers/acpi, dated October 2026, page cache_setup_acpi(9). periodt. 🫶✨