find_resource_space(9)

✨ find_resource_space — a lil kernel API page ✨

okay so this is find_resource_space from the Kernel API Manual (section 9, kernel-space functions, iykyk) 💅

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🌸 NAME 🌸

find_resource_space — literally just: find empty space in the resource tree 🎀

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🦋 SYNOPSIS 🦋

int find_resource_space (struct resource *root , struct resource *new ,
resource_size_t size , struct resource_constraint *constraint );

bestie it returns an int, and yes the parameter is named new — I know, new is a keyword in other languages, don't come for me, it's C and it's fine 🫶

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💖 ARGUMENTS 💖

• root — the root resource descriptor. this is the top of the tree you're searching under, the main character of the whole operation 👑
• new — a resource descriptor that is awaiting an empty resource space. it's the one getting placed, the one we're doing all this for 🥺
• size — the minimum size of the empty space. no budget for less than this, periodt.
• constraint — the range and alignment constraints that have to be met. it's giving picky, but like, necessarily 🌈

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🔥 DESCRIPTION 🔥

So what it does: it finds an empty space under root in the resource tree that satisfies the range and alignment constraints. that's the whole vibe. it goes looking, it finds a hole that actually fits your requirements, and it's done ✨

no cap, that's it — the constraints are doing the heavy lifting here, and size is the floor for how big the hole has to be.

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👑 RETURN 👑

• 0 — if successful, new members start, end, and flags are altered. yes, it mutates your struct — that's the deal, bestie, it's filling in the details for you 💅
• -EBUSY — if no empty space was found. 😭 it looked, nothing fit, that's a wrap.

ngl, -EBUSY here doesn't mean "someone else is using it" in the usual sense — it means no empty space was found. don't get it twisted 🫶

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🌟 SEE ALSO 🌟

Kernel file ./kernel/resource.c — that's where the magic lives, go read it, I'm obsessed 🧚

and the whole resource-management friend group, fr fr:

• request_resource_conflict(9)
• request_resource(9)
• release_resource(9)
• find_next_res(9)
• walk_iomem_res_desc(9)
• region_intersects(9)
• reallocate_resource(9)
• allocate_resource(9)
• lookup_resource(9)
• insert_resource_conflict(9)
• insert_resource(9)
• insert_resource_expand_to_fit(9)
• remove_resource(9)
• adjust_resource(9)
• resource_alignment(9)
• __request_region(9)
• __release_region(9)
• release_mem_region_adjustable(9)
• merge_system_ram_resource(9)
• devm_request_resource(9)
• devm_release_resource(9)
• devm_request_free_mem_region(9)
• alloc_free_mem_region(9)

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that's the page, bestie 🌈 this one shipped from the ./kernel source tree, October 2026 edition — and the man page itself is find_resource_space(9), so you literally can't lose it. go find some space, slay 💜