SVC

System calls

Id	NF ARM11	NF ARM9	TF ARM11	Description	Notes
0x01	Yes	No	No	Result ControlMemory(u32* outaddr, u32 addr0, u32 addr1, u32 size, u32 operation, u32 permissions)	Outaddr is usually the same as the input addr0.
0x02	Yes	No	No	Result QueryMemory(MemoryInfo* info, PageInfo* out, u32 Addr)
0x03	Yes	No	No	void ExitProcess(void)
0x04	Yes	No	No	Result GetProcessAffinityMask(u8* affinitymask, Handle process, s32 processorcount)
0x05	Yes	No	No	Result SetProcessAffinityMask(Handle process, u8* affinitymask, s32 processorcount)
0x06	Yes	No	No	Result GetProcessIdealProcessor(s32 *idealprocessor, Handle process)
0x07	Yes	No	No	Result SetProcessIdealProcessor(Handle process, s32 idealprocessor)
0x08	Yes	Yes	Yes	Result CreateThread(Handle* thread, func entrypoint, u32 arg, u32 stacktop, s32 threadpriority, s32 processorid)
0x09	Yes	Yes	Yes	void ExitThread(void)
0x0A	Yes	Yes	Yes	void SleepThread(s64 nanoseconds)
0x0B	Yes	Yes	Yes	Result GetThreadPriority(s32* priority, Handle thread)
0x0C	Yes	Yes	Yes	Result SetThreadPriority(Handle thread, s32 priority)
0x0D	Yes	No	No	Result GetThreadAffinityMask(u8* affinitymask, Handle thread, s32 processorcount)
0x0E	Yes	No	No	Result SetThreadAffinityMask(Handle thread, u8* affinitymask, s32 processorcount)	Replaced with a stub in ARM11 NATIVE_FIRM kernel beginning with 8.0.0-18.
0x0F	Yes	No	No	Result GetThreadIdealProcessor(s32* processorid, Handle thread)
0x10	Yes	No	No	Result SetThreadIdealProcessor(Handle thread, s32 processorid)	Replaced with a stub in ARM11 NATIVE_FIRM kernel beginning with 8.0.0-18.
0x11	Yes	No	No	s32 GetCurrentProcessorNumber(void)
0x12	Yes	No	No	Result Run(Handle process, StartupInfo* info)	This starts the main() thread. Buf+0 is main-thread priority, Buf+4 is main-thread stack-size.
0x13	Yes	Yes	Yes	Result CreateMutex(Handle* mutex, bool initialLocked)
0x14	Yes	Yes	Yes	Result ReleaseMutex(Handle mutex)
0x15	Yes	Yes	Yes	Result CreateSemaphore(Handle* semaphore, s32 initialCount, s32 maxCount)
0x16	Yes	Yes	Yes	Result ReleaseSemaphore(s32* count, Handle semaphore, s32 releaseCount)
0x17	Yes	Yes	Yes	Result CreateEvent(Handle* event, ResetType resettype)
0x18	Yes	Yes	Yes	Result SignalEvent(Handle event)
0x19	Yes	Yes	Yes	Result ClearEvent(Handle event)
0x1A	Yes	Yes	Yes	Result CreateTimer(Handle* timer, ResetType resettype)
0x1B	Yes	Yes	Yes	Result SetTimer(Handle timer, s64 initial, s64 interval)
0x1C	Yes	Yes	Yes	Result CancelTimer(Handle timer)
0x1D	Yes	Yes	Yes	Result ClearTimer(Handle timer)
0x1E	Yes	No	No	Result CreateMemoryBlock(Handle* memblock, u32 addr, u32 size, u32 mypermission, u32 otherpermission)
0x1F	Yes	No	No	Result MapMemoryBlock(Handle memblock, u32 addr, u32 mypermissions, u32 otherpermission)
0x20	Yes	No	No	Result UnmapMemoryBlock(Handle memblock, u32 addr)
0x21	Yes	Yes	Yes	Result CreateAddressArbiter(Handle* arbiter)
0x22	Yes	Yes	Yes	Result ArbitrateAddress(Handle arbiter, u32 addr, ArbitrationType type, s32 value, s64 nanoseconds)
0x23	Yes	Yes	Yes	Result CloseHandle(Handle handle)
0x24	Yes	Yes	Yes	Result WaitSynchronization1(Handle handle, s64 nanoseconds)
0x25	Yes	Yes	Yes	Result WaitSynchronizationN(s32* out, Handle* handles, s32 handlecount, bool waitAll, s64 nanoseconds)
0x26	Yes	No	No	Result SignalAndWait(s32* out, Handle signal, Handle* handles, s32 handleCount, bool waitAll, s64 nanoseconds)	Stubbed
0x27	Yes	Yes	Yes	Result DuplicateHandle(Handle* out, Handle original)
0x28	Yes	Yes	Yes	s64 GetSystemTick(void) (This returns the total CPU ticks elapsed since the CPU was powered-on)
0x29	Yes	No	No	Result GetHandleInfo(s64* out, Handle handle, HandleInfoType type)
0x2A	Yes	Yes	Yes	Result GetSystemInfo(s64* out, SystemInfoType type, s32 param)
0x2B	Yes	Yes	Yes	Result GetProcessInfo(s64* out, Handle process, ProcessInfoType type)
0x2C	Yes	Yes	Yes	Result GetThreadInfo(s64* out, Handle thread, ThreadInfoType type)
0x2D	Yes	No	No	Result ConnectToPort(Handle* out, const char* portName)
0x2E	Yes	No	No	Result SendSyncRequest1(Handle session)	Stubbed
0x2F	Yes	No	No	Result SendSyncRequest2(Handle session)	Stubbed
0x30	Yes	No	No	Result SendSyncRequest3(Handle session)	Stubbed
0x31	Yes	No	No	Result SendSyncRequest4(Handle session)	Stubbed
0x32	Yes	No	No	Result SendSyncRequest(Handle session)
0x33	Yes	No	No	Result OpenProcess(Handle* process, u32 processId)
0x34	Yes	No	No	Result OpenThread(Handle* thread, Handle process, u32 threadId)
0x35	Yes	No	Yes	Result GetProcessId(u32* processId, Handle process)
0x36	Yes	No	No	Result GetProcessIdOfThread(u32* processId, Handle thread)
0x37	Yes	Yes	Yes	Result GetThreadId(u32* threadId, Handle thread)
0x38	Yes	No	No	Result GetResourceLimit(Handle* resourceLimit, Handle process)
0x39	Yes	No	No	Result GetResourceLimitLimitValues(s64* values, Handle resourceLimit, LimitableResource* names, s32 nameCount)
0x3A	Yes	No	No	Result GetResourceLimitCurrentValues(s64* values, Handle resourceLimit, LimitableResource* names, s32 nameCount)
0x3B	Yes	No	No	Result GetThreadContext(ThreadContext* context, Handle thread)	Stubbed
0x3C	Yes	Yes	Yes	Break(BreakReason)
0x3D	Yes	Yes	Yes	OutputDebugString(void const, int)	Does nothing on non-debug units.
0x3E	Yes	No	No	ControlPerformanceCounter(unsigned long long, int, unsigned int, unsigned long long)
0x47	Yes	No	No	Result CreatePort(Handle* portServer, Handle* portClient, const char* name, s32 maxSessions)	Setting name=NULL creates a private port not accessible from svcConnectToPort.
0x48	Yes	No	No	Result CreateSessionToPort(Handle* session, Handle port)
0x49	Yes	No	No	Result CreateSession(Handle* sessionServer, Handle* sessionClient)
0x4A	Yes	No	No	Result AcceptSession(Handle* session, Handle port)
0x4B	Yes	No	No	Result ReplyAndReceive1(s32* index, Handle* handles, s32 handleCount, Handle replyTarget)	Stubbed.
0x4C	Yes	No	No	Result ReplyAndReceive2(s32* index, Handle* handles, s32 handleCount, Handle replyTarget)	Stubbed.
0x4D	Yes	No	No	Result ReplyAndReceive3(s32* index, Handle* handles, s32 handleCount, Handle replyTarget)	Stubbed.
0x4E	Yes	No	No	Result ReplyAndReceive4(s32* index, Handle* handles, s32 handleCount, Handle replyTarget)	Stubbed.
0x4F	Yes	No	No	Result ReplyAndReceive(s32* index, Handle* handles, s32 handleCount, Handle replyTarget)
0x50	Yes	Yes	Yes	Result BindInterrupt(Interrupt name, Handle syncObject, s32 priority, bool isManualClear)
0x51	Yes	Yes	Yes	Result UnbindInterrupt(Interrupt name, Handle syncObject)
0x52	Yes	Yes	Yes	Result InvalidateProcessDataCache(Handle process, void* addr, u32 size)
0x53	Yes	Yes	Yes	Result StoreProcessDataCache(Handle process, void const* addr, u32 size)
0x54	Yes	Yes	Yes	Result FlushProcessDataCache(Handle process, void const* addr, u32 size)
0x55	Yes	Yes	Yes	Result StartInterProcessDma(Handle* dma, Handle dstProcess, void* dst, Handle srcProcess, const void* src, u32 size, const DmaConfig& config)
0x56	Yes	Yes	Yes	Result StopDma(Handle dma)
0x57	Yes	Yes	Yes	Result GetDmaState(DmaState* state, Handle dma)
0x58	Yes	Yes	Yes	RestartDma(nn::Handle, void *, void const*, unsigned int, signed char)
0x60	Yes	No	No	Result DebugActiveProcess(Handle* debug, u32 processID)
0x61	Yes	No	No	Result BreakDebugProcess(Handle debug)
0x62	Yes	No	No	Result TerminateDebugProcess(Handle debug)
0x63	Yes	No	No	Result GetProcessDebugEvent(DebugEventInfo* info, Handle debug)
0x64	Yes	No	No	Result ContinueDebugEvent(Handle debug, u32 flags)
0x65	Yes	No	No	Result GetProcessList(s32* processCount, u32* processIds, s32 processIdMaxCount)
0x66	Yes	No	No	Result GetThreadList(s32* threadCount, u32* threadIds, s32 threadIdMaxCount, Handle domain)
0x67	Yes	No	No	Result GetDebugThreadContext(ThreadContext* context, Handle debug, u32 threadId, u32 controlFlags)
0x68	Yes	No	No	Result SetDebugThreadContext(Handle debug, u32 threadId, ThreadContext* context, u32 controlFlags)
0x69	Yes	No	No	Result QueryDebugProcessMemory(MemoryInfo* blockInfo, PageInfo* pageInfo, Handle process, u32 addr)
0x6A	Yes	No	No	Result ReadProcessMemory(void* buffer, Handle debug, u32 addr, u32 size)
0x6B	Yes	No	No	Result WriteProcessMemory(Handle debug, void const* buffer, u32 addr, u32 size)
0x6C	Yes	No	No	Result SetHardwareBreakPoint(s32 registerId, u32 control, u32 value)
0x6D	Yes	No	No	GetDebugThreadParam(long long *, int *, nn::Handle, unsigned int, nn::dmnt::DebugThreadParam)	Disabled on regular kernel.
0x70	Yes	No	No	Result ControlProcessMemory(Handle KProcess, unsigned int Addr0, unsigned int Addr1, unsigned int Size, unsigned int Type, unsigned int Permissions)
0x71	Yes	No	No	Result MapProcessMemory(Handle KProcess, unsigned int StartAddr, unsigned int EndAddr)
0x72	Yes	No	No	Result UnmapProcessMemory(Handle KProcess, unsigned int StartAddr, unsigned int EndAddr)
0x73	Yes	No	No	Result CreateCodeSet(Handle* handle_out, struct CodeSetInfo, u32 code_ptr, u32 ro_ptr, u32 data_ptr)
0x74	Yes	No	No	Result RandomStub()	Stubbed
0x75	Yes	No	No	Result CreateProcess(Handle* handle_out, Handle codeset_handle, u32 arm11kernelcaps_ptr, u32 arm11kernelcaps_num)
0x76	Yes	No	No	TerminateProcess(Handle)
0x77	Yes	No	No	Result SetProcessResourceLimits(Handle KProcess, Handle KResourceLimit)
0x78	Yes	No	No	Result CreateResourceLimit(Handle *KResourceLimit)
0x79	Yes	No	No	Result SetResourceLimitValues(Handle res_limit, LimitableResource* resource_type_list, s64* resource_list, u32 count)
0x7A	Yes	No	Yes	AddCodeSegment (unsigned int Addr, unsigned int Size)	Stubbed on NATIVE_FIRM beginning with 2.0.0-2. Used during TWL_FIRM boot.
0x7B	Yes	Yes	No	Backdoor(unsigned int CodeAddress)	This is used on ARM9 NATIVE_FIRM. No ARM11 processes have access to it without some form of kernelhax.
0x7C	Yes	Yes	Yes	KernelSetState(unsigned int Type, unsigned int Param0, unsigned int Param1, unsigned int Param2)	The type determines the meaning of each param
0x7D	Yes	No	No	Result QueryProcessMemory(MemInfo *Info, unsigned int *Out, Handle KProcess, unsigned int Addr)
0xFF	Yes	Yes	Yes	???	Debug related? The svcaccesscontrol mask doesn't apply for this SVC. Stubbed on ARM9 NATIVE_FIRM.

NF: NATIVE_FIRM. TF: TWL_FIRM.

Note that "stubbed" here means that the SVC only returns an error, as in the following snippet:

ROM:FFF04D98                 LDR             R0, =0xF8C007F4
ROM:FFF04D9C                 BX              LR

Types and structures

enum MemoryState

Memory state flags	Value
FREE	0
RESERVED	1
IO	2
STATIC	3
CODE	4
PRIVATE	5
SHARED	6
CONTINUOUS	7
ALIASED	8
ALIAS	9
ALIAS CODE	10
LOCKED	11

enum PageFlags

Page flags	Bit
LOCKED	0
CHANGED	1

enum MemoryOperation

Memory operation	Id
FREE	1
RESERVE	2
COMMIT	3
MAP	4
UNMAP	5
PROTECT	6
REGION APP	0x100
REGION SYSTEM	0x200
REGION BASE	0x300
LINEAR	0x10000

The LINEAR memory-operation indicates that the mapped physical address is always MappedVAddr+0x0C000000, thus this memory can be used for hardware devices' DMA(such as the GPU). Addr0+size for this must be within the 0x14000000-0x1C000000 range when Addr0 is non-zero(Addr1 must be zero), Addr0 isn't actually used by svcControlMemory for mapping memory: Addr0 is not used by the kernel after doing address-range checks. The kernel determines what physical-address to use by allocating memory from FCRAM(about the same way as other memory), which is then used to determine the virtual-address.

8.0.0-18 added a new memory mapping(0x30000000-0x38000000) for LINEAR memory, this replaces the original mapping for newer titles. The kernel uses the new mapping when the process memory-region is BASE, or when the process kernel-release-version field is >=0x022c(2.44 / system-version 8.0.0-18).

The input mem-region value for svcControlMemory is only used(when non-zero) when the PID is value 1, for the FIRM ARM11 "loader" module.

enum MemoryPermission

Memory permission	Id
NONE	0
R	1
W	2
RW	3
X	4
RX	5
WX	6
RWX	7
DONTCARE	0x10000000

enum ResetType

Reset type	Id
ONESHOT	0
STICKY	1
PULSE	2

struct MemoryInfo

Type	Field
u32	Base process virtual address
u32	Size
u32	Permission
enum MemoryState	State

struct PageInfo

Type	Field
u32	Flags

struct StartupInfo

Type	Field
s32	Priority
u32	Stack size
s32	argc
s16*	argv
s16*	envp

enum ArbitrationType

Address arbitration type	Value
FREE	0
AQUIRE	1
KERNEL2	2
AQUIRE_TIMEOUT	3
KERNEL4	4

enum BreakReason

Break Reason	Value
PANIC	0
ASSERT	1
USER	2

struct CodeSetInfo

All addresses are given virtual for the process to be created. All sizes are given in 0x1000-pages.

Type	Field
u8[8]	Codeset Name
u16	Unknown, this is written to field 0x5A of KCodeSet
u16	Unknown/padding
u32	Unknown/padding
u32	.text addr
u32	.text size
u32	.rodata start
u32	.rodata size
u32	RW addr (.data + .bss)
u32	RW size (.data + .bss)
u32	Total .text pages
u32	Total .rodata pages
u32	Total RW pages (.data + .bss)
u32	Unknown/padding
u8[8]	Program ID

struct DebugEventInfo

Type	Field
u32	Event type
u32	Thread ID (not used in all events)
u32[2]	Unknown/padding
u32[6]	Event-specific data (see below)

Event type	Id
PROCESS	0
CREATE THREAD	1
EXIT THREAD	2
EXIT PROCESS	3
EXCEPTION	4
DLL LOAD	5
DLL UNLOAD	6
SCHEDULE IN	7
SCHEDULE OUT	8
SYSCALL IN	9
SYSCALL OUT	10
OUTPUT STRING	11
MAP	12

PROCESS event

Type	Field
u64	Program ID
char[8]	Process name
u32	Process ID
u32	0 = newly created process, 1 = attached process

CREATE THREAD event

Type	Field
u32	Creator thread ID
u32	Base address (?)
u32	Entrypoint

EXIT THREAD/PROCESS events

A single u32 reason field is used.

Thread exit reasons:

Reason	Id
(None)	0
TERMINATE	1
EXIT PROCESS	2
TERMINATE PROCESS	3

Process exit reasons:

Reason	Id
(None)	0
TERMINATE	1
UNHANDLED EXCEPTION	2

EXCEPTION event

Type	Field
u32	Exception type
u32	Exception address
u32	Argument (type-specific)

Exception types:

Reason	Id	Argument
UNDEFINED INSTRUCTION	0	(None)
(Unknown)	1	(None)
(Unknown, mem-related)	2	Address
(Unknown, mem-related)	3	Address
ATTACH BREAK	4	(None)
BREAKPOINT	5	(None)
USER BREAK	6	User break type
DEBUGGER BREAK	7	(None)
UNDEFINED SYSCALL	8	Attempted syscall ID

User break types:

Reason	Id
PANIC	0
ASSERT	1
USER	2

SCHEDULER/SYSCALL IN/OUT events

Type	Field
u64	Clock tick
u32	Syscall (only for SYSCALL events)

OUTPUT STRING event

Type	Field
u32	String address
u32	String size

MAP event

Type	Field
u32	Mapped address
u32	Mapped size
u32	MemoryPermission
u32	MemoryState

svcSetHardwareBreakPoint

This is essentially an interface for writing values to the debug-unit (B/W)RP registers. registerId range 0..5 = breakpoints(BRP0-5), 0x100..0x101 = watchpoints(WRP0-1), anything outside of these ranges will result in an error. This is used for both adding and removing/disabling breakpoints/watchpoints, hence the raw control value parameter.

Here the kernel sets bit15 in the DSCR, to enable monitor-mode debugging.

Regardless of whether this is for a BRP, when bit21 is set in the control input parameter(BRP type = contextID), the kernel will load the target process contextID and use that internally for the value field. The target process is specified via a KDebug handle passed as the "value" parameter.

Lastly, the kernel disables the specified (B/W)RP, then writes the value parameter / loaded contextID to the (B/W)VR, then writes the input control value to the (B/W)CR.

Processes

Each process can only use SVCs which are enabled in the exheader for this process. The ARM11 kernel SVC handler checks whether the SVC is enabled in the syscall access control mask stored on the SVC-mode stack, when the SVC isn't enabled a kernelpanic() is triggered. Each process has a separate SVC-mode stack, this stack and the syscall access mask stored here is initialized when the process is started. Applications normally only have access to SVCs <=0x3D, however not all SVCs <=0x3D are accessible to the application. The majority of the SVCs accessible to applications are unused by the application.

Each process has a separate handle-table, the size of this table is stored in the exheader. The handles in a handle-table can't be used in the context of other processes, since those handles don't exist in other handle-tables.

0xFFFF8001 is a handle alias for the current KProcess, and 0xFFFF8000 is a handle alias for the current KThread.

Calling svcBreak on retail will only terminate the process which called this SVC.

Threads

For svcCreateThread the input address used for Entrypoint_Param and StackTop are normally the same, however these can be arbitrary. For the main thread the Entrypoint_Param is value 0.

Using CloseHandle() with a KThread handle will terminate the specified thread, only if the reference count reaches 0.

Lower priority values give the thread higher priority. For userland apps, priorities between 0x18 and 0x3F are allowed. The priority of the app's main thread seems to be 0x30.

The thread scheduler is cooperative, therefore if a thread takes up all the CPU time (for example if it enters an endless loop), all the other threads that run on the same CPU core won't get a chance to run. The main way of yielding another thread is using an address arbiter.

Memory Mapping

ControlMemory and MapMemoryBlock can be used to map memory pages, these two SVCs only support mapping execute-never R/W pages. The input permissions parameter for these SVCs must therefore be <=3, where value zero is used when un-mapping memory. Furthermore it appears that only regular heap pages can be mirrored (it won't work for TLS, stack, .data, .text, for example).

Bitmask 0xF00 for ControlMemory parameter MemoryType is the memory-type, when this is zero the memory-type is loaded from the kernel flags stored in the exheader ARM11 kernel descriptors, for the process using the SVC.

ControlMemory parameter MemoryType with value 0x10003 is used for mapping the GSP heap. The low 8-bits are the type: 1 is for un-mapping memory, 3 for mapping memory. Type4 is used to mirror the RW memory at Addr1, to Addr0. Type4 will return an error if Addr1 is located in read-only memory. Addr1 is not used for type1 and type3.

The ARM11 kernel does not allow processes to create shared memory blocks via svcCreateMemoryBlock, when the process memorytype(from the kernel flags stored in the exheader kernel descriptor) is the application memorytype, and when addr=0. It's unknown how the kernel handles addr=0 when the memorytype is not the application memorytype. When addr is non-zero, it must be located in memory which is already mapped. Furthermore, it appears that only regular heap pages (allocated using svcControlMemory op=COMMIT) are accepted as valid addrs.

ControlProcessMemory maps memory in the specified process, this is the only SVC which allows mapping executable memory. Format of the permissions field for memory mapping SVCs: bit0=R, bit1=W, bit2=X. Type6 sets the Addr0 memory permissions to the input permissions, for already mapped memory. Type is the MemoryOperation enum, without the memory-type/memory-region. ControlProcessMemory only supports type4, type5, and type6. ControlProcessMemory does not support using the current KProcess handle alias.

MapProcessMemory maps RW memory starting at address 0x00100000 in the specified KProcess, at the specified StartAddr in the current process. MapProcessMemory then maps 0x08000000 in the specified process, to StartAddr+0x7f00000 in the current process. UnmapProcessMemory unmaps the memory which was mapped by MapProcessMemory.

Note that with the MAP MemoryOperation, the kernel will refuse to MAP memory for the specified addr1, when addr1 was already used with another MAP operation as addr1. The kernel also doesn't allow memory to be freed via the FREE MemoryOperation, when other virtual-memory is mapped to this same memory(when the MAP MemoryOperation was used with this memory with addr1).

DMA

The CTRSDK code for using svcStartInterProcessDma will execute svcBreak when svcStartInterProcessDma returns an error(except for certain error value(s)). Therefore on retail, triggering a svcStartInterProcessDma via a system-module which results in an error from svcStartInterProcessDma will result in the system-module terminating.

Debugging

DebugActiveProcess is used to attach to a process for debugging. This SVC can only be used when the target process' ARM11 descriptors stored in the exheader have the kernel flag for "Enable debug" set. Otherwise when that flag is clear, the kernel flags for the process using this SVC must have the "Force debug" flag set.

KernelSetState

Type	Enabled for the NATIVE_FIRM ARM11 kernel	Enabled for the TWL_FIRM ARM11 kernel	Description
0	Yes	No	This initializes the programID for launching FIRM, then triggers launching FIRM. Param0 is unused. Param1 is the programID-low, and the programID-high is 0x00040138. Param2 is used only with the New_3DS kernel, pm-module uses value 0 with this. With New3DS kernel, it forces the programIDlow to be the New3DS NATIVE_FIRM, when the input programIDlow is for the Old3DS NATIVE_FIRM and Param2==0.
1	Yes	Yes	Unknown, does nothing with the TWL_FIRM ARM11 kernel.
2	Yes	Yes	?
3	Yes	No	This used for initializing the 0x1000-byte buffer used by the launched FIRM. Param2 is unused. When Param0 is value 1, this buffer is copied to the beginning of FCRAM at 0xF0000000, and Param1 is unused. When Param0 is value 0, this kernel buffer is mapped to process address Param1.
4	No	Yes	Param0-Param3 are unused. This unmaps(?) the following virtual memory by writing value physaddr(where physaddr base is 0x80000000) to the L1 MMU table entries: 0x00300000..0x04300000, 0x08000000..0x0FE00000, and 0x10000000..0xF8000000.
5	Yes	Yes	?
6	Yes	No	Debug related?
7	Yes	No	This triggers an MCU (hard) reboot. Param0-3 are unused. This reboot is triggered via device address 0x4A on the second I2C bus (the MCU). Register address 0x20 is written to with value 4. This code will not return.
8	Yes	No	Alternate unused FIRM launch code-path, with different PXI FIFO word constants.
9	Yes, implemented at some point after system-version v4.5.	?	Unknown
10	Yes	?	ConfigureNew3DSCPU. Only available for the New_3DS kernel. Param0 = input value. Only bit0-1 are used here. This configures the hardware register for the flags listed here, among other code which uses the MPCore private memory region registers.

GetSystemInfo

SystemInfoType value	s32 param	Description
0	0	This writes the total used memory size in the following memory regions to out: APPLICATION, SYSTEM, and BASE.
0	1	This writes the total used memory size in the APPLICATION memory region to out.
0	2	This writes the total used memory size in the SYSTEM memory region to out.
0	3	This writes the total used memory size in the BASE memory region to out.
25	Unused	This writes the total number of threads which were directly launched by the kernel, to out.
26	Unused	This writes the total number of processes which were directly launched by the kernel, to out. For the NATIVE_FIRM/SAFE_MODE_FIRM ARM11 kernel, this is normally 5, for processes sm, fs, pm, loader, and pxi.

GetProcessInfo

Input:

R0 = unused
R1 = Handle process
R2 = ProcessInfoType type

Output:

R0 = Result
R1 = output value lower word
R2 = output value upper word

ProcessInfoType value	Available since system version	Description
9-19	8.0.0-18	This only returns error 0xD8E007ED.
20	8.0.0-18	low u32 = (0x20000000 - <LINEAR virtual-memory base for this process>). That is, the output value is the value which can be added to LINEAR memory vaddrs for converting to physical-memory addrs.
21-23	8.0.0-18	This only returns error 0xE0E01BF4.

GetHandleInfo

HandleInfoType value	Description
0	This returns the time in ticks the KProcess referenced by the handle was created. If a KProcess handle was not given, it will write whatever was in r5, r6 when the svc was called.
1	Get internal refcount-1 for kernel object (u32), and also a boolean if the refcount-1 is negative (u32).
0x32107	Returns (u64) 0.

svc7B Backdoor

This saves SVC-mode SP+LR on the user-mode stack, then sets the SVC-mode SP to the user-mode SP. This then calls the specified code in SVC-mode. Once the called code returns, this pops the saved SP+LR off the stack for restoring the SVC-mode SP, then returns from the svc7b handler. Note that this svc7b handler does not disable IRQs, if any IRQs/context-switches occur while the SVC-mode SP is set to the user-mode one here, the ARM11-kernel will crash(which hangs the whole ARM11-side system).

Kernel error-codes

See Error codes.

Error-code value	Description
0x09401BFE	Timeout occurred with svcWaitSynchronization*, when timeout is not ~0.
0xC8601801	No more unused/free synchronization objects left to use in a given object's linked list. (KEvent, KMutex, KTimer, KSemaphore, KAddressArbiter, KThread)
0xC8601802	No more unused/free KSharedMemory objects left to use in the KSharedMemory linked list - out of blocks
0xC8601809	No more unused/free KSessions left to use in the KSession linked list - out of sessions
0xC860180A	Not enough free memory available for memory allocation.
0xC920181A	The session was closed by the other process..
0xD0401834	Max connections to port have been exceeded
0xD88007FA	Returned if no KObjectName object in the linked list of such objects matches the port name provided to the svc.
0xD8E007ED	This indicates that a value is outside of the enum being used.
0xD8E007F1	This error indicates Misaligned address.
0xD8E007F7	This error indicates that the input handle used with the SVC does not exist in the process handle-table, or that the handle kernel object type does not match the type used by the SVC.
0xD9000402	Invalid memory permissions for input/output buffers, for svcStartInterProcessDma.
0xD9001814	Failed unprivileged load or store - wrong permissions on memory
0xD9001BF7	This error is returned when the kernel retrieves a pointer to a kernel object, but the object type doesn't match the desired one.
0xD92007EA	This error is returned when a process attempts to use svcCreateMemoryBlock when the process memorytype is the application memorytype, and when addr=0.
0xE0E01BF5	This indicates an invalid address was used.
0xF8C007F4	Invalid type/param0-param3 input for svcKernelSetState. This is also returned for those syscalls marked as stubs.