acpi_pptt_g...rom_cache_id(9)

Welcome to the acpi_pptt_get_cpumask_from_cache_id(9) page in the Kernel API Manual, bestie 💖. This one is lowkey iconic: it’s all about grabbing the CPUs tied to a specific cache, and it’s giving “topology detective” energy 🕵️‍♀️🦋.

🌸 NAME 🌸

acpi_pptt_get_cpumask_from_cache_id — get the cpus associated with the specified cache 💅

✨ SYNOPSIS ✨

int acpi_pptt_get_cpumask_from_cache_id (u32 cache_id , cpumask_t *cpus
);

💅 ARGUMENTS 💅

• cache_id — the id field of the cache 🎀
• cpus — where to build the cpumask 🫶

🦋 DESCRIPTION 🦋

okay so: figure out which CPUs are below this cache in the PPTT 🌸. This lets the property be found even if the CPUs are offline — yes, even then, bestie 😭👑

Also highkey important: the PPTT table must be rev 3 or later, periodt 🚨.

🎀 RETURN 🎀

-ENOENT if the PPTT doesn’t exist, or the cache cannot be found 💀. Otherwise it returns 0 and sets the cpus in the provided cpumask — slay ✨.

💖 SEE ALSO 💖

Kernel file ./drivers/acpi/pptt.c is the main character here, and the whole squad is:

• 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)
• cache_setup_acpi(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)

Signed off from ./drivers/acpi — October 2026 — on the acpi_pptt_get_cpumask_from_cache_id(9) page in the Kernel API Manual. mwah 💋🎀✨