System Settings allows you to manage various settings, use System Transfer, and use Data Management.
Data Management
3DS
Here you can manage 3DS extra data, and 3DSWare/"Software".
When managing 3DS Software installed to the SD Card, the title.db is read by the core receiving AM commands. From the title.db file, AM gets a list of installed titles, title sizes and the name of the ".cmd" file for each title, which is used to check the authenticity of the title data(product code, title version, and if an electronic manaual is used, is also kept for each title, in the title.db, but won't be used by the Data Management Utility). For each title listed, it checks if the title is authentic(via the .cmd file). If the title passes authentication, Data Management decrypts/reads the ICN data from the executable NCCH(CXI) and displays it along with the archived title size. If a title doesn't pass authentication, a placeholder icon(light grey with a '?' in the center), name ('????????') and a size of zero are used. Deleting titles removes the title data from the title.db and import.db, and deletes the directory of the content.
DSiWare
See DSiWare Exports.
System Format
Most of the System Format is done with FS:InitializeCtrFileSystem. This command updates the high u64 of the keyY stored in movable.sed. Since this keyY was updated, the data stored on SD card(sdmc/Nintendo 3DS/<ID0>/<ID1>) and the data under nand/data/<ID0> is rendered useless, since that data used the old keyY. Since that data is no longer usable, the system then deletes the two above SD/NAND directories.
System Updater
The system updater title is identical to the regular system settings, except only system update is accessible with this. On dev units, this title can only be launched under certain conditions.
On retail units, this title is accessible in scenarios where you have to update via the Internet to use certain 3DS software other than the home menu. i.e. using the eShop, on a system version less than the current one. When one selects "Cancel" from here on retail, the system will shutdown. NS launches SAFE_MODE_FIRM for running this title, when the UPDATEFLAG is set during system boot.
Exiting System Settings
Upon exit (return to home menu), system settings reloads and launches NATIVE_FIRM from NAND.
ExtData
The ExtData File System for System Settings is as follows:
root
├── icon
├── boss
└── user
├── Backup.dat
└── MsetExt.dat
| File | Details | Size | FW Introduced | Plaintext |
|---|---|---|---|---|
| icon | Stubbed. Always image 00000002. | 0x4 Bytes | n/a | |
| MsetExt.dat | DSiWare Exports Management | 0x960 Bytes | 2.0.0-2 | Download |
| Backup.dat | SD Savedata Backups Management | 0xf5a0 Bytes | 6.0.0-11 | Download |
MsetExt.dat
This keeps a record for the DSiWare Exports for a maximum of 300 exports. Each record is in the format:
| OFFSET | SIZE | DESCRIPTION |
|---|---|---|
| 0 | 4 | Game Code in Little Endian |
| 0x4 | 4 | Reserved |
All unused entries are filled with "0xff".
Backup.dat
This keeps a record for the 30 save data backup slots for SD Savedata Backups. Each entry corresponds to an individual backup slot.
Entry:
| OFFSET | SIZE | DESCRIPTION |
|---|---|---|
| 0x000 | 8 | Reserved |
| 0x8 | 0x800 (0x80*16) | 16 UTF-16 Title Strings |
| 0x808 | 8 | Title ID |
| 0x810 | 8 | Unknown |
| 0x818 | 8 | Total Save Data Size |
| 0x820 | 0x10 | Reserved |