get_pfn_range_for_nid(9)

💅 get_pfn_range_for_nid(9) — Kernel API Manual 🎀

okay bestie, welcome to the Kernel API Manual, and today's main character is get_pfn_range_for_nid — the little function that tells you where a node's memory actually lives. no cap, it's giving "where's the party and where does it end" energy ✨

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🌸 NAME 🌸

get_pfn_range_for_nid — returns the start and end page frames for a node 💖

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✨ SYNOPSIS ✨

void get_pfn_range_for_nid (unsigned int nid , unsigned long *start_pfn
, unsigned long *end_pfn );

like, that's the whole signature, and yes, she takes pointers — we love a function that writes back to you 🫶

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🦋 ARGUMENTS 🦋

• nid — the node id you want the range for, periodt. and here's the plot twist: if it's MAX_NUMNODES, you get the min and max PFN back instead. iykyk 😌
• start_pfn — passed by reference, bestie. on return it'll be holding the node start_pfn. she doesn't come empty, she comes filled in 💅
• end_pfn — same deal, also passed by reference. on return it'll have the node end_pfn. twin behavior, honestly iconic 🎀

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🔥 DESCRIPTION 🔥

so what does she actually do? she returns the start and end page frame of a node, based on the info that memblock_set_node handed over. that's the source of truth, no guessing 🌟

⚠️ but listen — if you call her for a node with no available memory, the start and end PFNs will both be 0. that's not a bug, that's just the vibe check coming back empty. don't @ me 😭

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💜 SEE ALSO 💜

• Kernel file ./mm/mm_init.c 📂
• absent_pages_in_range(9)
• free_area_init(9)
• node_map_pfn_alignment(9)

go read those if you're nosy, which — same 🧚

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and that's the whole page, bestie 🍓 straight from ./mm, October 2026 edition — get_pfn_range_for_nid(9), slaying in a kernel near you 🌈👑