early_init_f...reserved_mem(9)

✨ NAME ✨

early_init_fdt_scan_reserved_mem — bestie, this is the one that creates reserved memory regions 🎀 (yes, that's the whole vibe, and it ate)

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🌸 SYNOPSIS 🌸

void early_init_fdt_scan_reserved_mem (void );

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🦋 ARGUMENTS 🦋

• void — literally no arguments. zero. nada. she takes nothing and gives everything 💅

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🔥 DESCRIPTION 🔥

Okay so picture this: this function goes and grabs memory from the early allocator so that a device can have it all to itself — device exclusive use, no sharing, main character energy 👑 — and that exclusivity is defined in the device tree structures 🌳✨.

The way it works is very "call me at the right moment" though, so listen up: arch specific code should call this once the early allocator (i.e. memblock) has been fully activated. Not before. That's the whole thing. Timing is everything, iykyk 💖

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💜 SEE ALSO 💜

Kernel file ./drivers/of/fdt.c, plus the whole friend group:

• unflatten_dt_nodes(9)
• __unflatten_device_tree(9)
• of_fdt_unflatten_tree(9)
• early_init_fdt_reserve_self(9)
• of_scan_flat_dt(9)
• of_scan_flat_dt_subnodes(9)
• of_get_flat_dt_subnode_by_name(9)
• of_fdt_is_compatible(9)
• of_flat_dt_is_compatible(9)
• of_flat_dt_match_machine(9)
• early_init_dt_check_for_initrd(9)
• early_init_dt_check_for_elfcorehdr(9)
• early_init_dt_check_for_usable_mem_range(9)
• early_init_dt_check_kho(9)
• unflatten_device_tree(9)
• unflatten_and_copy_device_tree(9)

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ngl this whole page lives in ./drivers/of and it's giving October 2026 — part of the Kernel API Manual, section 9, filed under early_init_f...reserved_mem(9). Go read the source bestie, it's iconic 🫶⭐🌈

okay bye, go reserve some memory, slay 💅✨🍓