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NRO is the executable format for non-ExeFS binaries.

It starts with the NRO-start structure then the "NRO" header and mainly describes .text, .rodata, and .data segments (like a short-form of ELF program headers):


Offset Size Description
0x0 0x4 Unused. Originally 0x0, with [17.0.0+] this is set to value 0x1.
0x4 0x4 MOD0 offset
0x8 0x4 [1.0.0-16.1.0] Padding. [17.0.0+] nnSdk version offset
0xC 0x4 Padding


Offset Size Description
0x0 0x4 Magic "NRO0"
0x4 0x4 Version (always 0)
0x8 4 Size (total NRO file size)
0xC 0x4 Flags (unused)
0x10 0x8 * 3 SegmentHeader[3] {.text, .ro, .data}
0x28 0x4 BssSize
0x2C 0x4 Reserved
0x30 0x20 ModuleId
0x50 0x04 DsoHandleOffset (unused)
0x54 0x04 Reserved (unused)
0x58 0x8 * 3 SegmentHeader[3] {.apiInfo, .dynstr, .dynsym}


Offset Size Description
0x0 0x4 MemoryOffset
0x4 0x4 Size


Value of "build id" from ELF's GNU .note section. Contains variable sized digest, up to 32bytes.


This is an optional custom assets section for homebrew, this is located at file offset {NroHeader.size}. See also switch-tools for implementation.

The below offsets are relative to the beginning of the assets section (AssetHeader).


Offset Size Description
0x0 0x4 Magic "ASET"
0x4 0x4 Format version, currently 0.
0x8 0x10 AssetSection icon. Used by the Homebrew Launcher. Like official icons, this is a 256x256 JPEG.
0x18 0x10 AssetSection NACP. Used by the Homebrew Launcher.
0x28 0x10 AssetSection romfs. Can be used by the application.


Offset Size Description
0x0 0x8 Offset
0x8 0x8 Size, 0 indicates this section is empty.