merge_system_ram_resource(9)

💅 merge_system_ram_resource(9) 💅

okay so this is a page from the Kernel API Manual — yes, the Kernel API Manual, we're literally reading kernel docs for fun now, this is the energy we're bringing ✨

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🌸 NAME 🌸

merge_system_ram_resource — marks the System RAM resource as mergeable and then tries to merge it with adjacent resources that are also mergeable 🫶

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🎀 SYNOPSIS 🎀

void merge_system_ram_resource (struct resource *res );

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🦋 ARGUMENTS 🦋

• res — the resource descriptor, bestie. that's it, that's the whole argument 💅

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✨ DESCRIPTION ✨

so this interface? it's intended for memory hotplug, okay. picture it: a driver is adding a whole bunch of contiguous system ram resources (like, via add_memory*()), and honestly the actual resource boundaries are not of interest here — lowkey irrelevant, for example it might be relevant for DIMMs 🧚

only resources that check all these boxes get considered:

• they're marked mergeable,
• they have the same parent,
• and they don't have any children.

periodt. those are the rules 💖

and one more thing — all mergeable resources must be immutable during the request. no cap. they gotta stay still while this is happening 🔥

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💀 NOTE 💀

• the caller has to make sure that no pointers to resources that are marked mergeable are used anymore after this call — because the resource might be freed and the pointer might be stale! 😭 like genuinely, that's a use-after-free vibe and we do not want it 🙈
• release_mem_region_adjustable will split on demand on memory hotunplug 👑

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🌈 SEE ALSO 🌈

kernel file ./kernel/resource.c — and the whole friend group:

• request_resource_conflict(9)
• request_resource(9)
• release_resource(9)
• find_next_res(9)
• walk_iomem_res_desc(9)
• region_intersects(9)
• find_resource_space(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)
• devm_request_resource(9)
• devm_release_resource(9)
• devm_request_free_mem_region(9)
• alloc_free_mem_region(9)

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ngl the mergeable-resource rules are strict bestie, read the NOTE section twice before you ship 🫶

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okay and for the sign-off: this lil beauty comes from ./kernel and it's dated October 2026 — that's the source, the version, and the date, all accounted for, slay 💜🎀✨