Filesystem services

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Revision as of 12:17, 24 September 2018 by Shchmue (talk | contribs) (→‎OpenContentStorageFileSystem: fix link to old page/fn name)
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This is "nn::fssrv::sf::IFileSystemProxyForLoader".

Cmd Name Arguments Notes
0 OpenCodeFileSystem u64 TitleId + X descriptor #ContentPath Returns an #IFileSystem.
1 IsArchivedProgram u64 ProcessId Returns a bool (1 if code is mounted).
2 [4.0.0+] SetCurrentProcess PID descriptor


This is "nn::fssrv::sf::IProgramRegistry".

Cmd Name Notes
0 #RegisterProgram
1 #UnregisterProgram
2 [4.0.0+] SetCurrentProcess
256 #SetEnabledProgramVerification


Takes a storageID, a pid, a titleID, a 0x1C type-A buffer for the FS Access Header, and a 0x2C type-A buffer for the FS Access Control

Final FS permissions are stored as (ACI0_perms & ACID_perms). Will panic(svcBreak) when buffer sizes from ipc-rawdata are invalid.


Takes a pid. Removes registered FS permissions for that PID.


Seems to sets a global flag to inputval & 1.

When the flag is zero, it will set ret=0 instead of ret={error} when verifying the fixed-key NPDM ACID signature fails. This also skips verifying the NCA Header signature using the ACID key. Note that if verifying the fixed-key ACID signature is successful, and verifying the ACID-key NCA header signature fails, it will throw an error and abort.


This is "nn::fssrv::sf::IFileSystemProxy".

Cmd Name
0 [1.0.0] #OpenFileSystem
1 #SetCurrentProcess
2 OpenDataFileSystemByCurrentProcess
7 [2.0.0+] #OpenFileSystemWithPatch
8 [2.0.0+] #OpenFileSystemWithId
9 [3.0.0+] OpenDataFileSystemByApplicationId
11 #OpenBisFileSystem
12 #OpenBisStorage
13 InvalidateBisCache
17 OpenHostFileSystem
18 OpenSdCardFileSystem
19 [2.0.0+] FormatSdCardFileSystem
21 #DeleteSaveDataFileSystem
22 #CreateSaveDataFileSystem
23 #CreateSaveDataFileSystemBySystemSaveDataId
24 RegisterSaveDataFileSystemAtomicDeletion
25 [2.0.0+] DeleteSaveDataFileSystemBySaveDataSpaceId
26 [2.0.0+] FormatSdCardDryRun
27 [2.0.0+] IsExFatSupported
28 [4.0.0+] DeleteSaveDataFileSystemBySaveDataAttribute
30 #OpenGameCardStorage
31 #OpenGameCardFileSystem
32 [3.0.0+] ExtendSaveDataFileSystem
33 [5.0.0+] DeleteCacheStorage
34 [5.0.0+] GetCacheStorageSize
35 [6.0.0+] ? (Takes a total of 0xB0-bytes of input, no output)
51 #OpenSaveDataFileSystem
52 #OpenSaveDataFileSystemBySystemSaveDataId
53 [2.0.0+] OpenReadOnlySaveDataFileSystem
57 [3.0.0+] ReadSaveDataFileSystemExtraDataBySaveDataSpaceId
58 ReadSaveDataFileSystemExtraData
59 [2.0.0+] WriteSaveDataFileSystemExtraData
60 #OpenSaveDataInfoReader
61 #OpenSaveDataInfoReaderBySaveDataSpaceId
62 [5.0.0+] OpenCacheStorageList
64 [5.0.0+] OpenSaveDataInternalStorageFileSystem
65 [5.0.0+] UpdateSaveDataMacForDebug
66 [5.0.0+] WriteSaveDataFileSystemExtraData2
67 [6.0.0+] ? (Takes a total of 0x50-bytes of input, returns 8-bytes of output, and a type-0x6 output buffer)
68 [6.0.0+] ? (Takes a total of 0x50-bytes of input, returns an #ISaveDataInfoReader)
80 OpenSaveDataMetaFile
81 [4.0.0+] OpenSaveDataTransferManager (No input, returns an #ISaveDataTransferManager)
82 [5.0.0+] OpenSaveDataTransferManagerVersion2 (No input, returns an #ISaveDataTransferManagerWithDivision)
83 [6.0.0+] OpenSaveDataTransferProhibiterForCloudBackUp (Takes an input u64, returns an #ISaveDataTransferProhibiter)
84 [6.0.0+] ? (Takes a total of 0x10-bytes of input, returns 4-bytes of output, and a type-0x6 output buffer)
100 OpenImageDirectoryFileSystem
110 #OpenContentStorageFileSystem
120 [6.0.0+] ? (Takes 4-bytes of input, returns an #IFileSystem)
200 OpenDataStorageByCurrentProcess
201 [3.0.0+] OpenDataStorageByProgramId
202 #OpenDataStorageByDataId
203 OpenPatchDataStorageByCurrentProcess
400 #OpenDeviceOperator
500 #OpenSdCardDetectionEventNotifier
501 #OpenGameCardDetectionEventNotifier
510 [5.0.0+] OpenSystemDataUpdateEventNotifier
511 [5.0.0+] NotifySystemDataUpdateEvent
520 [6.0.0+] ? (Takes a total of 0xC-bytes of input, no output)
600 [1.0.0-3.0.2] SetCurrentPosixTime
601 QuerySaveDataTotalSize
602 #VerifySaveDataFileSystem
603 CorruptSaveDataFileSystem
604 CreatePaddingFile
605 DeleteAllPaddingFiles
606 [2.0.0+] GetRightsId
607 [2.0.0+] RegisterExternalKey
608 [2.0.0+] UnregisterAllExternalKey
609 [2.0.0+] GetRightsIdByPath
610 [3.0.0+] GetRightsIdAndKeyGenerationByPath
611 [4.0.0+] SetCurrentPosixTimeWithTimeDifference
612 [4.0.0+] GetFreeSpaceSizeForSaveData
613 [4.0.0+] VerifySaveDataFileSystemBySaveDataSpaceId
614 [4.0.0+] CorruptSaveDataFileSystemBySaveDataSpaceId
615 [5.0.0+] QuerySaveDataInternalStorageTotalSize
616 [6.0.0+] #GetSaveDataCommitId
620 [2.0.0+] #SetSdCardEncryptionSeed
630 [4.0.0+] SetSdCardAccessibility
631 [4.0.0+] IsSdCardAccessible
640 [4.0.0+] IsSignedSystemPartitionOnSdCardValid
700 [5.0.0+] OpenAccessFailureResolver
701 [5.0.0+] GetAccessFailureDetectionEvent
702 [5.0.0+] IsAccessFailureDetected
710 [5.0.0+] ResolveAccessFailure
720 [5.0.0+] AbandonAccessFailure
800 [2.0.0+] GetAndClearFileSystemProxyErrorInfo
1000 SetBisRootForHost
1001 SetSaveDataSize
1002 SetSaveDataRootPath
1003 DisableAutoSaveDataCreation
1004 #SetGlobalAccessLogMode
1005 #GetGlobalAccessLogMode
1006 #OutputAccessLogToSdCard
1007 [4.0.0+] RegisterUpdatePartition
1008 [4.0.0+] OpenRegisteredUpdatePartition
1009 [4.0.0+] GetAndClearMemoryReportInfo
1010 [5.1.0+]
1100 [4.0.0+] OverrideSaveDataTransferTokenSignVerificationKey
1200 [6.0.0+] ? (No input, returns an output #IMultiCommitManager)


Every time permissions are checked, the process registration #fsp-pr is loaded using the session processID. The permission data is populated with data from the NPDM.

If the processID is <= 6 (which happens only for built-in sysmodules), it will use a hardcoded registration data. The default mask in this case is 0x8000000000000000.

Note that the functions check whether or not at least one bit is set in the mask. This means that, you don't need to set 0xFFFFFFFFFFFFFFFF to get all permissions: it suffices to set 0x8000000000000000.

If the code were to request an invalid input type, panic. But this never happens.


Type(s) Mask Name Value Used by
0x0 0x8000000000000801 MountLogo 1 #OpenFileSystem, #OpenFileSystemWithPatch, #OpenFileSystemWithId
0x1 0x8000000000000801 MountContentMeta 1 #OpenFileSystem, #OpenFileSystemWithPatch, #OpenFileSystemWithId
0x2 0x8000000000000801 MountContentControl 1 #OpenFileSystem, #OpenFileSystemWithPatch, #OpenFileSystemWithId
0x3 0x8000000000000801 MountContentManual 1 #OpenFileSystem, #OpenFileSystemWithPatch, #OpenFileSystemWithId
0x4 0x8000000000000801 MountContentData 1 #OpenFileSystem, #OpenFileSystemWithPatch, #OpenFileSystemWithId
0x5 0x8000000000000801 MountApplicationPackage 1 #OpenFileSystem, #OpenFileSystemWithPatch, #OpenFileSystemWithId
0x6 0x8000000000000000 3
0x7 0x8000000000000800 ContentStorageAccess 3 #OpenContentStorageFileSystem
0x8 0x8000000000001000 ImageDirectoryAccess 3 #OpenImageDirectoryFileSystem
0x9 0x8000000000000084 OpenBisFileSystemType28, OpenBisFileSystemType32 3 #OpenBisFileSystem
0xA 0x8000000000000080 OpenBisFileSystemType29 3 #OpenBisFileSystem
0xB 0x8000000000008080 OpenBisFileSystemType30 3 #OpenBisFileSystem
0xC 0x8000000000008080 OpenBisFileSystemType31 3 #OpenBisFileSystem
0xD 0x8000000000000080 3
0xE 0x8000000000000080 ([1.0.0-2.3.0] 0xC000000000200000) OpenBisFileSystemType33 3 #OpenBisFileSystem
0xF 0xC000000000200000 ([1.0.0-2.3.0] 0x8000000000000010) SdCardAccess 3 #OpenSdCardFileSystem
0x10 0x8000000000000010 ([1.0.0-2.3.0] 0x8000000000040020) GameCardUser 3 #OpenGameCardFileSystem
0x11 0x8000000000040020 ([1.0.0-2.3.0] 0x8000000000000028) SaveDataAccess0 3 #OpenSaveDataFileSystem
0x12 0x8000000000000028 ([1.0.0-2.3.0] 0x8000000000000020) SystemSaveDataAccess0 3 #OpenSaveDataFileSystemBySystemSaveDataId
0x13 0x8000000000000020 SaveDataAccess1 3 #OpenSaveDataFileSystem
0x14 0x8000000000000020 ([1.0.0-2.3.0] 0x8000000000010082) SystemSaveDataAccess1 3 #OpenSaveDataFileSystemBySystemSaveDataId
0x15 0x8000000000010082 ([1.0.0-2.3.0] 0x8000000000010080) BisPartition0 3 #OpenBisStorage
0x16 0x8000000000010080 BisPartition10 3 #OpenBisStorage
0x17 0x8000000000000080 ([1.0.0-2.3.0] 0x8000000000010080) BisPartition20 3 #OpenBisStorage
0x18 0x8000000000010080 BisPartition21 3 #OpenBisStorage
0x19 0x8000000000010080 BisPartition22 3 #OpenBisStorage
0x1A 0x8000000000010080 BisPartition23 3 #OpenBisStorage
0x1B 0x8000000000010080 BisPartition24 3 #OpenBisStorage
0x1C 0x8000000000010080 BisPartition25 3 #OpenBisStorage
0x1D 0x8000000000010080 ([1.0.0-2.3.0] 0x8000000000000084) BisPartition26 3 #OpenBisStorage
0x1E 0x8000000000000084 BisPartition27 3 #OpenBisStorage
0x1F 0x8000000000000084 ([1.0.0-2.3.0] 0x8000000000000080) BisPartition28 3 #OpenBisStorage
0x20 0x8000000000000080 BisPartition29 3 #OpenBisStorage
0x21 0x8000000000000080 BisPartition30 3 #OpenBisStorage
0x22 0x8000000000000080 BisPartition31 3 #OpenBisStorage
0x23 0x8000000000000080 ([1.0.0-2.3.0] 0xC000000000200000) BisPartition32 3 #OpenBisStorage
0x24 0x8000000000000080 ([1.0.0-2.3.0] 0x8000000000000100) BisPartition33 3 #OpenBisStorage
0x25 0xC000000000200000 ([1.0.0-2.3.0] 0x8000000000100008)
0x26 0x8000000000000100 ([1.0.0-2.3.0] 0xC000000000400000) GameCard_System 3 #OpenGameCardStorage, #EraseGameCard (bit1), #WriteToGameCard (bit1), #GetGameCardErrorInfo (bit1), #EraseAndWriteParamDirectly (bit1), #ReadParamDirectly (bit1), #ForceEraseGameCard (bit1)
[3.0.0+] 0x27 0x8000000000100008 MountContent_System 1 #OpenFileSystem, #OpenDataStorageByDataId
[3.0.0+] 0x28 0xC000000000400000 HostAccess 3 #OpenHostFileSystem
[4.0.0+] 0x29 0x8000000000010000 RegisteredUpdatePartitionAccess 1 #OpenRegisteredUpdatePartition
[5.0.0+] 0x2A 0x8000000000000000 SaveDataInternalStorageAccess 3 #OpenSaveDataInternalStorageFileSystem


Type(s) Mask Name Used by
0x0 0x8000000000000080 BisCache #InvalidateBisCache
0x1 0x8000000000000080 EraseMmc #EraseMmc
0x2 0x8000000000000010 GameCardCertificate #GetGameCardDeviceCertificate
0x3 0x8000000000000010 GameCardIdSet #GetGameCardIdSet
0x4 0x8000000000000200 GameCardDriver #FinalizeGameCardDriver
0x5 0x8000000000000200 GameCardAsic #GetGameCardAsicInfo
0x6 0x8000000000002020 SaveDataCreate #CreateSaveDataFileSystem
0x7 0x8000000000000060 SaveDataDelete0 #DeleteSaveDataFileSystem, #RegisterSaveDataFileSystemAtomicDeletion
0x8 0x8000000000000028 SystemSaveDataCreate0 #CreateSaveDataFileSystemBySystemSaveDataId
0x9 0x8000000000000020 SystemSaveDataCreate1 #CreateSaveDataFileSystemBySystemSaveDataId
0xA 0x8000000000004028 SaveDataDelete1 #DeleteSaveDataFileSystem, #RegisterSaveDataFileSystemAtomicDeletion
0xB 0x8000000000000060 SaveDataInfoReader0 #OpenSaveDataInfoReaderBySaveDataSpaceId, #OpenSaveDataInfoReader
0xC 0x8000000000004020 SaveDataInfoReader1 #OpenSaveDataInfoReaderBySaveDataSpaceId, #OpenSaveDataInfoReader
0xD 0x8000000000020000 SaveDataMeta #OpenSaveDataMetaFile
0xE 0x8000000000000400 PosixTime #SetCurrentPosixTime, #SetCurrentPosixTimeWithTimeDifference
0xF 0x8000000000004060 SaveDataExtraData_Read #ReadSaveDataFileSystemExtraData
0x10 0x8000000000080000 GlobalAccessMode #SetGlobalAccessMode
0x11 0x8000000000080000 SpeedEmulationMode #SetSpeedEmulationMode
0x12 Invalid
0x13 0xC000000000800000 PaddingFiles #CreatePaddingFile, #DeleteAllPaddingFiles
0x14 0xC000000001000000 SaveDataCorrupt0 #CorruptSaveDataFileSystem, #CorruptSaveDataFileSystemBySaveDataSpaceId
0x15 0x8000000001000060 ([1.0.0-4.1.0] 0xC000000002000000) SaveDataCorrupt1 #CorruptSaveDataFileSystem, #CorruptSaveDataFileSystemBySaveDataSpaceId
[2.0.0+] 0x16 0x8000000000000060 ([1.0.0-4.1.0] 0x8000000004000000) SaveDataVerify #VerifySaveDataFileSystem, #VerifySaveDataFileSystemBySaveDataSpaceId
[2.0.0+] 0x17 0xC000000002000000 ([1.0.0-4.1.0] 0x8000000008000000) SaveData_SystemManagement #CreateSaveDataFileSystem, #OpenSaveDataFileSystem, #SetSaveDataRootPath
[2.0.0+] 0x18 0x8000000004000000 ([1.0.0-4.1.0] 0x8000000010000000) SdCardFormat #FormatSdCardFileSystem
[2.0.0+] 0x19 0x8000000008000000 ([1.0.0-4.1.0] 0x8000000000000800) RightsId #GetRightsId, #GetRightsIdAndKeyGenerationByPath, #GetRightsIdByPath
[2.0.0+] 0x1A 0x8000000010000000 ([1.0.0-4.1.0] 0x8000000000004020) ExternalKey #RegisterExternalKey, #UnregisterAllExternalKey
[3.0.0+] 0x1B 0x8000000000000800 ([1.0.0-4.1.0] 0x8000000000002020) SdCardEncryptionSeed #SetSdCardEncryptionSeed
[3.0.0+] 0x1C 0x8000000000004020 ([1.0.0-4.1.0] 0x8000000000000028) SaveDataExtraData_Write0 #WriteSaveDataFileSystemExtraData, #WriteSaveDataFileSystemExtraData2
[4.0.0+] 0x1D 0x8000000000000000 ([1.0.0-4.1.0] 0x8000000020000000) SaveDataExtraData_Write1 #WriteSaveDataFileSystemExtraData, #WriteSaveDataFileSystemExtraData2
[4.0.0+] 0x1E 0x8000000000002020 ([1.0.0-4.1.0] 0x8000000040000000) SaveDataExtend0 #ExtendSaveDataFileSystem
[4.0.0+] 0x1F 0x8000000000000028 ([1.0.0-4.1.0] 0x8000000000000000) SaveDataExtend1 #ExtendSaveDataFileSystem
[4.0.0+] 0x20 0x8000000020000000 ([1.0.0-4.1.0] 0x8000000000000000) UpdatePartitionRegister #RegisterUpdatePartition
[5.0.0+] 0x21 0x8000000040000000 SaveDataTransfer #OpenSaveDataTransferManager
[5.0.0+] 0x22 0x0000000080000002 SaveDataTransferVersion2 #OpenSaveDataTransferManagerVersion2
[5.0.0+] 0x23 0x8000000000000000 MmcPatrol #SuspendMmcPatrol, #ResumeMmcPatrol
[5.0.0+] 0x24 0x8000000000000000 SaveDataTransferKey #OverrideSaveDataTransferTokenSignVerificationKey
[5.0.0+] 0x25 0x8000000080200000 SdCardDetectionEventNotifier #OpenSdCardDetectionEventNotifier
[5.0.0+] 0x26 0x8000000080000110 GameCardDetectionEventNotifier #OpenGameCardDetectionEventNotifier
[5.0.0+] 0x27 0x8000000000100008 SystemDataUpdateEventNotifier #OpenSystemDataUpdateEventNotifier
[5.0.0+] 0x28 0x8000000080010000 SystemDataUpdateEventNotify #NotifySystemDataUpdateEvent
[5.0.0+] 0x29 0x0000000080000001 AccessFailureResolver #OpenAccessFailureResolver
[5.0.0+] 0x2A 0x0000000080000001 AccessFailureDetectionEvent #GetAccessFailureDetectionEvent
[5.0.0+] 0x2B 0x0000000080000001 AccessFailureDetected #IsAccessFailureDetected
[5.0.0+] 0x2C 0x0000000080000001 AccessFailureResolve #ResolveAccessFailure
[5.0.0+] 0x2D 0x0000000080000001 AccessFailureAbandon #AbandonAccessFailure
[5.0.0+] 0x2E 0x8000000040000000 SaveDataInternalStorageTotalSize #QuerySaveDataInternalStorageTotalSize
[5.0.0+] 0x2F 0x8000000080200000 SdCardAccessibility #SetSdCardAccessibility
[5.1.0+] 0x30 0x8000000080080000


Takes a type-0x19 input buffer (ContentPath) and a #FileSystemType as parameters. Returns an #IFileSystem.

[2.0.0+] This function was removed.


Takes a pid-descriptor.


Takes an input #FileSystemType and an u64 title-id. Returns an #IFileSystem.

Web-applet loads the #FileSystemType (which must be ContentManual) from u32_table[inparam].

Note: web-applet strings refer to both this cmd and #OpenFileSystemWithId as "MountContent", but official nn_sf_sync symbols use "OpenXX" names.


Takes a type-0x19 input buffer, an #FileSystemType and an u64 title-id. Returns an #IFileSystem.

The #IFileSystem must be ContentMeta if the NCA type is 0 (control).

The input buffer is the output string path from GetApplicationContentPath.

May return errors when attempting to access NCA-paths for an update-title with a gamecard, when the gamecard isn't inserted. May return error 0x7D402 in some cases with update-titles. Non-val2 in32 values with NCA-type1 are unusable, even for normal titles.

The official "MountApplicationPackage" func uses this with in64=0 and #FileSystemType ApplicationPackage.

After the #FileSystemType specific permissions are checked, it then gets the func retval for permissions-type 0x25 and func0.

When #FileSystemType is ContentMeta, it uses in64=0xffffffffffffffff internally, otherwise it checks if in64 is set to 0xffffffffffffffff then throws an error if so. When the in64 used internally is not 0xffffffffffffffff, it's compared with the NCA titleID, then an error is thrown on mismatch.


Takes a type-0x19 input buffer string and a u32 Bis partitionID. Official user-process code sets instr[0] = 0 normally. Returns an #IFileSystem.

Only partitionIDs for FAT partitions are usable with this, otherwise error 0x2EE202 is returned. Seems to be about the same as #OpenBisStorage except this mounts the partition filesystem instead of allowing direct access to the partition sectors.


Takes a u32 partition ID, returns 0x2EE202 for partitions which do not exist, 0x320002 for partitions which cannot be opened and a valid #IStorage handle otherwise.


Seems to invalidate the Bis cache for MBR/GPT after overwriting that data via the OpenBisStorage IStorage. Used by SystemInitializer.


Takes an input u64.


Takes a 0x40-byte Save-struct entry, a 0x40-byte SaveCreate-struct entry, and a 0x10-byte input struct.

Only the first 0x5-bytes in the 0x10-byte struct are initialized: all-zero when automatically creating savedata during savecommon mount by official user-processes. In the dedicated save-creation code in official user-processes: +0 u32 = 0x40060, +4 u8 = 1.

Creates regular savedata.


Takes a 0x40-byte Save-struct entry and a 0x40-byte SaveCreate-struct entry.

Creates savedata in the SYSTEM NAND partition.


Takes two input u32s (gamecard handle, partition ID), and returns an #IStorage for the partition.


Takes two input u32s, with the second u32 located at +4 in rawdata after the first u32. Returns an #IFileSystem.

Mounts a gamecard partition.


Takes an input u8 #SaveDataSpaceId and a 0x40-byte Save-struct entry. Official user-process code is only known to use value 1 for the u8.

Returns an #IFileSystem.

Permissions aren't checked until the specified save is successfully found.

Only one process (specifically only one #IFileSystem session) can mount a given savedata at any given time (this includes SystemSaveData).


Takes an input u8 #SaveDataSpaceId and a 0x40-byte Save-struct entry. Web-applet only uses value0 for the input u8.

Returns an #IFileSystem.

Mounts savedata in the SYSTEM NAND partition.


No input, returns an output #ISaveDataInfoReader.


Takes an input u8 #SaveDataSpaceId, returns an output #ISaveDataInfoReader.


Takes a #ContentStorageId. Invalid values return 0x2EE202.

Returns an #IFileSystem with NCA files. The read data from these files is identical to the data read by NCM_services#ReadContentIdFile.


Takes a #StorageId and a TitleID.

Returns a domain object ID implementing the #IStorage interface for data archives.


This command returns a session to a port implementing the #IDeviceOperator interface.


This command returns a session to a port implementing the #IEventNotifier interface.


This command returns a session to a port implementing the #IEventNotifier interface.


Takes an unknown input u64 and a type-0x6 output buffer.

The input u64 high-byte must be non-zero, otherwise an error is returned(0xE02).


Takes an input u8 and u64, returns an output u64.


Takes in the 0x10 byte SD card encryption seed, and loads it into FS-module state.

NS-module reads the 0x10 bytes from SdCard:/Nintendo/Contents/private, and compares them to the first 0x10 bytes of the ns_appman:/private (in system savedata 0x8000000000000043). If they match, NS calls this command using bytes 0x10-0x20 from ns_appman:/private. The rest of this file (0x1F0 bytes total) is (usually/always?) all-zero.


Takes an input u32.


Returns an output u32.

GlobalAccessLogMode is normally 0.


Takes a type-0x5 input buffer.

The input buffer is the string to output to the log. User-processes normally include a newline at the end.

User-processes only use this when the value previously loaded from #GetGlobalAccessLogMode has bit1 set.

When bit1 in GlobalAccessLogMode is clear, FS-module will just return 0 for OutputAccessLogToSdCard. However even with that set the log doesn't show up SD, unknown why.

The input buffer is written to the "$FsAccessLog:/FsAccessLog.txt" file, where "$FsAccessLog" is the SD-card mount-name. It's written to the current end of the file(appended).


This is "nn::fssrv::sf::IStorage".

This is the interface for a raw device, usually a block device.

Cmd Name Arguments
0 Read Takes a type-0x46 buffer, an offset and length
1 Write Takes a type-0x45 buffer, an offset and length
2 Flush None
3 SetSize Takes a size
4 GetSize None
5 [4.0.0+] OperateRange


This is "nn::fssrv::sf::IFileSystem".

There are two main implementations of this interface:

  • RomFS: Filesystem implementation statically linked in the binary. Uses an #IStorage interface as underlying raw device.
  • IPC proxy: Used for all non-RomFS filesystems. In this case, actual filesystem implementation is in the FS process.
Cmd Name
0 CreateFile
1 DeleteFile
2 CreateDirectory
3 DeleteDirectory
4 DeleteDirectoryRecursively
5 RenameFile
6 RenameDirectory
7 #GetEntryType
8 #OpenFile
9 #OpenDirectory
10 #Commit
11 #GetFreeSpaceSize
12 #GetTotalSpaceSize
13 [3.0.0+] #CleanDirectoryRecursively
14 [3.0.0+] GetFileTimeStampRaw
15 [4.0.0+] QueryEntry


Takes a type-0x9 input buffer for the path and returns #DirectoryEntryType as an output u32.


Takes a type-0x19 input buffer for the path, and an u32 mode. mode controls how the file is opened, based on which bits are set:

  • When bit 0 is set, the file is Readable: you can use the Read operation.
  • When bit 1 is set, the file is Writable: you can use the Write operation.
  • When bit 2 is set, the file is Appendable: unless this bit is set, you will not be able to write beyond the end of a file (such writes will result in an error 0x307202)


Takes a type-0x9 input buffer for the path and an u64 filter_flags. filter_flags controls what type of entries are read by the #IDirectory: bitmask 0x1 = directories, bitmask 0x2 = files.


Like 3DS, this has to be used after writing to savedata for the changes to take affect.


Takes a type-0x9 input buffer for the path and returns an output byte-size u64 for the total free space with this FS.


Takes a type-0x9 input buffer for the path and returns an output byte-size u64 for the total space available with this FS(free+used).


Takes a type-0x9 input buffer for the path and clears the contents of the directory specified in the path.


This is "nn::fssrv::sf::IDirectory".

Cmd Name
0 #Read
1 #GetEntryCount


Takes a type-0x6 output buffer. Returns an output u64(?) for the total number of read entries, this is 0 when no more entries are available.

The output buffer contains the read array of #DirectoryEntry. This doesn't include entries for "." and "..".


Returns an u64 for the total number of readable entries.


Offset Size Description
0x0 0x300 Path
0x300 0x4 ?
0x304 0x1 #DirectoryEntryType
0x305 0x3 Padding?
0x308 0x8? Filesize, 0 for directories.


s8 type: 0 = directory, 1 = file.


This is "nn::fssrv::sf::IFile".

Cmd Name
0 Read
1 Write
2 Flush
3 SetSize
4 GetSize
5 [4.0.0+] OperateRange


This is "nn::fssrv::sf::ISaveDataInfoReader".

Cmd Name
0 #ReadSaveDataInfo


Takes a type-0x6 output buffer. Returns an output u64 for total output entries. This buffer contains an array of #SaveDataInfo.

This is used to get #SaveDataInfo for all savedata on the system (or all savedata for the current #SaveDataSpaceId). When used multiple times, it will resume reading where it left off, until no more entries are available (in that case the out u64 is value 0).


This is "nn::fssrv::sf::IDeviceOperator".

Cmd Name
0 IsSdCardInserted
1 GetSdCardSpeedMode
2 [2.0.0+] GetSdCardCid
3 [2.0.0+] GetSdCardUserAreaSize
4 [2.0.0+] GetSdCardProtectedAreaSize
5 [2.0.0+] GetAndClearSdCardErrorInfo
100 GetMmcCid
101 GetMmcSpeedMode
110 EraseMmc
111 GetMmcPartitionSize
112 [2.0.0+] GetMmcPatrolCount
113 [2.0.0+] GetAndClearMmcErrorInfo
114 [2.0.0+] GetMmcExtendedCsd
115 [4.0.0+] SuspendMmcPatrol
116 [4.0.0+] ResumeMmcPatrol
200 IsGameCardInserted
201 EraseGameCard
202 GetGameCardHandle
203 #GetGameCardUpdatePartitionInfo
204 FinalizeGameCardDriver
205 GetGameCardAttribute
206 GetGameCardDeviceCertificate
207 GetGameCardAsicInfo
208 GetGameCardIdSet
209 WriteToGameCard
210 SetVerifyWriteEnalbleFlag
211 GetGameCardImageHash
212 [2.0.0+] GetGameCardErrorInfo
213 [2.0.0+] EraseAndWriteParamDirectly
214 [2.0.0+] ReadParamDirectly
215 [2.0.0+] ForceEraseGameCard
216 [2.0.0+] GetGameCardErrorInfo2
217 [2.1.0+] GetGameCardErrorReportInfo
218 [3.0.0+] GetGameCardDeviceId
300 SetSpeedEmulationMode
301 GetSpeedEmulationMode
400 [5.0.0+] SuspendSdmmcControl
401 [5.0.0+] ResumeSdmmcControl
402 [6.0.0+] ? (Takes a total of 4-bytes of input, returns a total of 8-bytes of output)
500 [6.0.0+] ? (Takes a total of 0x14-bytes of input, no output)
501 [6.0.0+] ? (Takes a total of 4-bytes of input, no output)


Returns a titleID and the title-version for it.

  • Output u32 with ARMS-gamecard: title-version v131162. This is the title-version for 2.1.0, which is the sysupdate included with this gamecard. Launch-day gamecards return title-version v450.
  • Output u64 with ARMS-gamecard: titleID 0100000000000816.

NS appears to only use this with Content_Manager_services#GetTitleIdInfo and Content_Manager_services#GetUpdateTitleList with storageid=nandsys, for checking whether a sysupdate is required.


This is "nn::fssrv::sf::IEventNotifier".

Cmd Name
0 GetEventHandle


Cmd Name
0 ? (No input/output, takes a type-0x6 output buffer)
16 ? (No input/output, takes a type-0x5 input buffer)
32 ? (Takes a total of 0x10-bytes of input, returns an unknown output interface)
33 ? (Takes a total of 0x10-bytes of input and a type-0x5 input buffer, returns an unknown output interface)
34 [6.0.0+] ? (No input/output, takes a type-0x5 input buffer, returns an unknown output interface)
64 ? (Takes a total of 0x18-bytes of input and a type-0x5 input buffer, returns an unknown output interface)
65 ? (Takes a total of 0x10-bytes of input and a type-0x5 input buffer, returns an unknown output interface)
66 [6.0.0+] ? (Takes a total of 0x10-bytes of input and a type-0x5 input buffer, returns an unknown output interface)
67 [6.0.0+] ? (Takes a total of 0x18-bytes of input and a type-0x5 input buffer, returns an unknown output interface)
68 [6.0.0+] ? (No input/output, takes a type-0x5 input buffer, returns an unknown output interface)
69 [6.0.0+] ? (Takes a total of 0x18-bytes of input, no output)

This was added with 5.0.0.

Cmd32-34 return the same interface. Cmd64-69 return the same interface.


This was added with 6.0.0.

This doesn't seem to handle any commands (?).


Cmd Name
1 ? (Takes an input #IFilesystem, no output)
2 ? (No input/output)

This was added with 6.0.0.


Value Name
0 Invalid
1 Invalid
2 Logo
3 ContentControl
4 ContentManual
5 ContentMeta
6 ContentData
7 ApplicationPackage


Value Name
0 None
1 Host
2 GameCard
3 NandSystem
4 NandUser
5 SdCard


Value Name
0 NandSystem
1 NandUser
2 SdCard


Value Name
0 NandSystem
1 NandUser
2 SdCard
3 [3.0.0+] TemporaryStorage

Determines the storage where the savedata is stored.


Value Name
0 SystemSaveData
1 SaveData
2 BcatDeliveryCacheStorage
3 DeviceSaveData
4 [3.0.0+] TemporaryStorage
5 [3.0.0+] CacheStorage


These are the 0x300 paths to NCA files for the various filesystems FS can access, beginning with @. They're passed via X descriptors, and returned via various ncm/lr commands.

Path Notes
@GcApp Gamecard App partition (Partition 2)
@GcS00000001 Gamecard Contents.
@upp Gamecard update partition (Partition 0)
[4.0.0+] @RegUpdate Registered update partition

Save Struct

Offset Size Description
0x0 0x8 0 for SystemSaveData. SaveData: 0 can be used for accessing the savedata associated with the current FS session titleID, otherwise when set this is the titleID associated with the savedata to access.
0x8 0x10 userID for user-specific savedata(saveuser) when set, otherwise when zero this indicates the common savedata(savecommon). This is loaded from Account_services.
0x18 0x8 u64 saveID. 0 for SaveData.
0x20 0x1 #SaveDataType
0x21 0x7 Padding
0x28 0x8 0 for SystemSaveData/SaveData.
0x30 0x8 0 for SystemSaveData/SaveData.
0x38 0x8 0 for SystemSaveData/SaveData.

Total size is 0x40-bytes.

For DeviceSaveData, this struct is all-zero except for the #SaveDataType field.

SaveCreate Struct

Offset Size Description
0x0 0x8 IVFC level4 size?
0x8 0x8 Same as offset 0x0 normally? Hard-coded to 0x80000 for BcatSaveData.
0x10 0x8 0x4000 for SystemSaveData/SaveData/DeviceSaveData/BcatSaveData. IVFC level4 block-size in bytes?
0x18 0x8 Official user-processes only uses 0 here for SystemSaveData/SaveData. For the dedicated save-creation code with SaveData/DeviceSaveData, this value comes from an input param with official user-processes. For BcatSaveData, this is the hard-coded titleID of the bcat-sysmodule.
0x20 0x4 Written using an input param for official user-processes. Hard-coded 0 for BcatSaveData.
0x24 0x1 Official user-processes only uses 0 here for SystemSaveData, 1 for SaveData/DeviceSaveData/BcatSaveData.
0x25 0x1 0 for SystemSaveData/SaveData.
0x26 0x1A Not initialized for SystemSaveData/SaveData.

Total size is 0x40-bytes.


This is accessed using the same commands for SaveData with the same input u8, the only difference compared to SaveData is the Save-struct.


This is accessed using the same commands for SaveData with the same input u8. The Save-struct is the same as DeviceSaveData, except that the titleID field is set to <input titleID>. See above regarding SaveCreate-struct.

The 0x10-byte struct passed to #CreateSaveDataFileSystem has the first 0x5-bytes set to all-zero.


Offset Size Description
0x0 0x8 Unknown saveID
0x8 0x1 #SaveDataSpaceId
0x9 0x1 #SaveDataType
0xA 0x6 Padding?
0x10 0x10 userID
0x20 0x8 saveID, 0 for regular SaveData.
0x28 0x8 Application titleID, for regular SaveData.
0x30 0x8 Raw saveimage size
0x38 0x28 Unknown. Usually zeros?

This is a 0x60-byte struct.