fdt_add_reservemap_entry(9)

💅 fdt_add_reservemap_entry(9) — Kernel API Manual

okay so real talk, bestie: this is a page from the Kernel API Manual and it's about one tiny little function that does one tiny little thing, and honestly? she's iconic for it. no cap.

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✨ NAME ✨

fdt_add_reservemap_entry — add an entry to the memory reserve map 🎀

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🌸 SYNOPSIS 🌸

int fdt_add_reservemap_entry (void *fdt , uint64_t addr , uint64_t size
);

like, yes, the ); is on its own line, that's just how she is, don't come for her 💅

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🦋 ARGUMENTS 🦋

• fdt — a pointer to the device tree blob. your main character. the blob herself 💖
• addr — the start address of the reserve map entry, fr fr
• size — how big the reserved region is

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💜 DESCRIPTION 💜

so fdt_add_reservemap_entry adds a memory reserve map entry to the device tree blob during the sequential write process. it's giving very "one brick at a time, in order, no skipping ahead" energy 🧱

and here's the part where you gotta pay attention, bestie — this function can only be called after fdt_create and before fdt_finish_reservemap. that's it. that's the window. miss it and it's not happening 🙈

think of it like a group chat that only lets you post between two specific messages. you post outside that window? blocked. no drama, just mechanics 🫶

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🔥 RETURN 🔥

• 0 — on success 🎉 slay, we ate
• -FDT_ERR_NOSPACE — if there is insufficient space in the blob 😭 the blob said "no room, I'm full"
• -FDT_ERR_BADSTATE — if not in the correct sequential write state 💀 you jumped the queue, and the queue said absolutely not

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👑 SEE ALSO 👑

the kernel file lives at ./scripts/dtc/libfdt/libfdt.h and she is surrounded by so many friends. literally the whole extended fdt family reunion, iykyk:

fdt_offset_ptr(9), fdt_next_tag(9), fdt_first_subnode(9), fdt_next_subnode(9), fdt_for_each_subnode(9), fdt_header_size(9), fdt_header_size_(9), fdt_check_header(9), fdt_move(9), fdt_check_full(9), fdt_get_string(9), fdt_string(9), fdt_find_max_phandle(9), fdt_get_max_phandle(9), fdt_generate_phandle(9), fdt_num_mem_rsv(9), fdt_get_mem_rsv(9), fdt_subnode_offset_namelen(9), fdt_subnode_offset(9), fdt_path_offset_namelen(9), fdt_path_offset(9), fdt_get_name(9), fdt_first_property_offset(9), fdt_next_property_offset(9), fdt_for_each_property_offset(9), fdt_get_property_by_offset(9), fdt_get_property_namelen(9), fdt_get_property(9), fdt_getprop_by_offset(9), fdt_getprop_namelen(9), fdt_getprop(9), fdt_get_phandle(9), fdt_get_alias_namelen(9), fdt_get_alias(9), fdt_get_symbol_namelen(9), fdt_get_symbol(9), fdt_get_path(9), fdt_supernode_atdepth_offset(9), fdt_node_depth(9), fdt_parent_offset(9), fdt_node_offset_by_prop_value(9), fdt_node_offset_by_phandle(9), fdt_node_check_compatible(9), fdt_node_offset_by_compatible(9), fdt_stringlist_contains(9), fdt_stringlist_count(9), fdt_stringlist_search(9), fdt_stringlist_get(9), FDT_MAX_NCELLS(9), fdt_address_cells(9), fdt_size_cells(9), fdt_setprop_inplace_namelen_partial(9), fdt_setprop_inplace(9), fdt_setprop_inplace_u32(9), fdt_setprop_inplace_u64(9), fdt_setprop_inplace_cell(9), fdt_nop_property(9), fdt_nop_node(9), fdt_create_with_flags(9), fdt_create(9), fdt_resize(9), fdt_finish_reservemap(9), fdt_begin_node(9), fdt_property(9), fdt_property_placeholder(9), fdt_end_node(9), fdt_finish(9), fdt_create_empty_tree(9), fdt_open_into(9), fdt_pack(9), fdt_add_mem_rsv(9), fdt_del_mem_rsv(9), fdt_set_name(9), fdt_setprop_namelen(9), fdt_setprop(9), fdt_setprop_placeholder_namelen(9), fdt_setprop_placeholder(9), fdt_setprop_u32(9), fdt_setprop_u64(9), fdt_setprop_cell(9), fdt_setprop_string(9), fdt_setprop_namelen_string(9), fdt_setprop_empty(9), fdt_appendprop(9), fdt_appendprop_u32(9), fdt_appendprop_u64(9), fdt_appendprop_cell(9), fdt_appendprop_string(9), fdt_appendprop_addrrange(9), fdt_delprop(9), fdt_add_subnode_namelen(9), fdt_add_subnode(9), fdt_del_node(9), fdt_overlay_apply(9), fdt_overlay_target_offset(9), fdt_strerror(9)

like… ninety-something cross-references. she said "you WILL know my whole family." obsessed with the thoroughness honestly 🌈

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that's the whole page, bestie — source is ./scripts/dtc/libfdt, dated October 2026, and the header/footer vibe is fdt_add_reservemap_entry(9) all the way down 🦋 mwah, go add your reserve map entry responsibly ✨