SVC

System calls

Note: The argument-lists here apply to the official syscall wrapper-functions that are found in userland processes. The actual ordering passed to the kernel via the SVC instruction is documented in Kernel ABI.

Id	NF ARM11	NF ARM9	TF ARM11	Description	Notes
0x01	Yes	No	No	Result ControlMemory(u32* outaddr, u32 addr0, u32 addr1, u32 size, MemoryOperation operation, MemoryPermission 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_nanoseconds, 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, MemoryPermission mypermission, MemoryPermission otherpermission)
0x1F	Yes	No	No	Result MapMemoryBlock(Handle memblock, u32 addr, MemoryPermission mypermissions, MemoryPermission 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 timeout_nanoseconds)
0x25	Yes	Yes	Yes	Result WaitSynchronizationN(s32* out, Handle* handles, s32 handlecount, bool waitAll, s64 timeout_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 reason) Break(BreakReason debugReason, const void* croInfo, u32 croInfoSize)
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, s16 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 eventOrSemaphore, s32 priority, bool isLevelHighActive)
0x51	Yes	Yes	Yes	Result UnbindInterrupt(Interrupt name, Handle eventOrSemaphore)
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(Handle, void *, void const*, unsigned int, signed char)
0x59	Yes	No?	No	SetGpuProt(s8 input_flag). Implemented with 11.3.0-X, see below.
0x5A	Yes	No?	No	SetWifiEnabled(s0 input_flag). Implemented with 11.4.0-X, see below.
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, const ThreadContext* context, u32 controlFlags)
0x69	Yes	No	No	Result QueryDebugProcessMemory(MemoryInfo* blockInfo, PageInfo* pageInfo, Handle debug, 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(s64* unused, u32* out, Handle kdebug, u32 threadId, DebugThreadParameter param)
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 process, u32 startAddr, u32 size)
0x72	Yes	No	No	Result UnmapProcessMemory(Handle process, u32 startAddr, u32 size)
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, and this was removed on 11.0.0-33 (for ARM11).
0x7C	Yes	Yes	Yes	KernelSetState(unsigned int Type, ...)	The type determines the args to be passed
0x7D	Yes	No	No	Result QueryProcessMemory(MemInfo *Info, unsigned int *Out, Handle KProcess, unsigned int Addr)
0xFF	Yes	Yes	Yes	Stop point	The svcaccesscontrol mask doesn't apply for this SVC. This svc doesn't check the "debug mode enabled" flag either. Does nothing if there is no KDebug object associated to the current process. 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 ResetType

Reset type	Id
ONESHOT	0
STICKY	1
PULSE	2

Timers/Events may be waited on by a thread using svcWaitSynchronization. Once the timer runs out/the event gets signaled, threads waiting on the respective handles until the timer/event is reset. STICKY timers/events wake up threads until they are explicitly reset by some thread. ONESHOT timers/events will wake up exactly one thread and then are reset automatically. PULSE timers will be reset after waking up one thread too, but will also be started again immediately. It's unknown whether PULSE is a valid reset type for events.

struct StartupInfo

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

enum BreakReason

Break Reason	Value
PANIC	0
ASSERT	1
USER	2

struct DebugEventInfo

Size: 0x28 bytes

When using svcGetProcessDebugEvent, the kernel fetches the first KEventInfo instance of the process's KDebug. The debug event is handled and parsed into this structure.

Type	Field
u32	Event type
u32	Thread ID (not used in all events)
u32	Flags. Bit0 means that svcContinueDebugEvent needs to be called for this event
u8[4]	Remnants of the corresponding flags in KEventInfo, always 0 here
u32[6]	Event-specific data (see below)

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

(1) Non-blocking: all other events preempt and block all the threads of their process until they are continued.

(2) There is handling code in the kernel but nothing signal those events.

(3) Completely removed from the kernel, but referenced in DMNT. Stubbed relocation code (e.g., in Process9 and in PXI sysmodule) and even whole libraries (e.g., in PXI sysmodule's .rodata section) seem to indicate that Nintendo used dynamic libraries early in system development.

When calling svcDebugActiveProcess, an ATTACH PROCESS debug event is signaled, then ATTACH THREAD for each of its opened threads, then finally ATTACH BREAK.

ATTACH THREAD events are also emitted when a thread is created from an attached process.

ATTACH PROCESS event

Type	Field
u64	Program ID
char[8]	Process name
u32	Process ID
u32	"Other" flag. Always 0 in available kernel versions

ATTACH THREAD event

Type	Field
u32	Creator thread ID (0 if attached by svcDebugActiveProcess)
void *	Thread local storage
u32 *	Entrypoint = .text load address of the parent process

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
DEBUG TERMINATE	2

EXCEPTION event

Type	Field
u32	Exception type
u32	Exception address
u32[4]	Type-specific data, see below

Exception types:

Exception type	Id
UNDEFINED INSTRUCTION	0
PREFETCH ABORT	1
DATA ABORT	2
UNALIGNED DATA ACCESS	3
ATTACH BREAK	4
STOP POINT	5
USER BREAK	6
DEBUGGER BREAK	7
UNDEFINED SYSCALL	8

UNDEFINED INSTRUCTION/PREFETCH ABORT/DATA ABORT/UNALIGNED DATA ACCESS/UNDEFINED SYSCALL events

Type	Field
u32	Fault information: Fault Address Register (for DATA ABORT and UNALIGNED DATA ACCESS), attempted SVC ID (for UNDEFINED SYSCALL), otherwise 0

STOP POINT event

Type	Field
u32	Stop point type that caused the event: 0 = svc 0xFF, 1 = breakpoint, 2 = watchpoint
u32	Fault information: FAR for watchpoints, 0 otherwise

USER BREAK event

Type	Field
u32	Break reason
u32[2]	Info for LOAD_RO and UNLOAD_RO

User break types:

Reason	Id
PANIC	0
ASSERT	1
USER	2
LOAD_RO	3
UNLOAD_RO	4

DEBUGGER BREAK event

Type	Field
s32[4]	IDs of the attached process's threads that were running on each core at the time of the @ref svcBreakDebugProcess call, or -1 (only the first 2 values are meaningful on O3DS).

SCHEDULE/SYSCALL IN/OUT events

Type	Field
u64	Clock tick
u32	CPU ID (SCHEDULE events) Syscall (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

struct ThreadContext

Size: 0xCC bytes

Offset	Type	Description
0x0	CpuRegisters	Saved CPU registers (r0-r12, sp, lr, pc, cpsr)
0x44	FpuRegisters	Saved FPU registers (d0-d15, fpscr, fpexc)

The user needs to adjust pc for exceptions that occured while in Thumb mode.

Flags for svcGetDebugThreadContext/svcSetDebugThreadContext:

Bit	Description
0	Get/set CPU GPRs (r0-r12)
1	Get/set CPU SPRs (sp, lr, pc, cpsr)
2	Get/set FPU GPRs (d0-d15 aka. f0-f31)
3	Get/set FPU SPRs (fpscr, fpexc)

When setting CPSR, the following assignment is done: ctx->cpsr = ctx->cpsr & 0x7F0FDFF | userCtx->cpuRegisters.cpsr & 0xF80F0200;. This is to avoid obvious security issues.

enum DebugThreadParameter

Parameter	Id
PRIORITY	0
SCHEDULING_MASK_LOW	1
CPU_IDEAL	2
CPU_CREATOR	3

typedef Handle

User-visible references to internal objects are represented by 32-bit integers called handles. Handles are only valid in the process they have been created in; hence, they cannot be exchanged between processes directly (the IPC functions provide a mean to copy handles to other processes, though).

There are a number of special-purpose handles, which provide easy access to information on objects in the current process:

Handle	Description
0xFFFF8000	Handle to the active thread
0xFFFF8001	Handle to the active process

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.

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.

Interrupt Handling

svcBindInterrupt registers the given event or semaphore corresponding to the handle to the global "interrupt table" for the given interrupt ID. Interrupts 0-14 and 16-31 can never be mapped regardless of the interrupt flags of the process's exheader, and the latter are not checked when mapping interrupt 15. The "is level high active"/"is manual clear" parameter must be false when binding a semaphore handle (otherwise 0xD8E007EE "invalid combination" is returned).

If something was already registered for the given ID, svcBindInterrupt returns error 0xD8E007F0. See KBaseInterruptEvent for more information on what happens on receipt of an interrupt.

Applications hence can wait for specific interrupts to happen by calling WaitSynchronization(N) on the event or semaphore handles.

The set of existing ARM11 interrupts is listed on this page.

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.

This SVC can only be used when a certain kernel state debug flag is non-zero(it's set to zero for retail).

KernelSetState

KernelSetState uses the 6th software-generated interrupt for any operation involving synchronization between cores.

Type	Enabled for the NATIVE_FIRM ARM11 kernel	Enabled for the TWL_FIRM ARM11 kernel	Description
0	Yes	No	Arguments : u64 firmTitleID (the high 32-bits of that title ID (0 when using N3DS pm) have a special meaning on N3DS, they're otherwise ignored, see below). This initializes the programID for launching FIRM, then triggers launching FIRM. With New3DS kernel, it forces the firm title ID to be the New3DS NATIVE_FIRM, when the input firm title ID is 2. The high firm title ID is always set to 0x40138. On New3DS, the kernel disables the additional New3DS cache hw prior to calling the firmlaunch function from the <handler for the KernelSetState-types called via funcptr>.
1	Yes	Yes	Does nothing.
2	Yes	Yes	Powers down the GPU and syncs with Process9 (waits for *(vu8 *)PXI_SYNC11 to be 1) during the process. On New3DS, the kernel disables the additional New3DS cache hw, when it's actually enabled, prior to executing the rest of the code from the <handler for the KernelSetState-types called via funcptr>.
3	Yes	No	Arguments: 0, void* address or 1 This used for initializing the 0x1000-byte buffer used by the launched FIRM. When the first parameter is 1, this buffer is copied to the beginning of FCRAM at 0xE0000000. When it is 0, this kernel buffer is mapped to the process address specified by the second argument.
4	No	Yes	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	Used by kernelpanic. This makes core0 enter a WFI/B infinite loop. Threads that were created on core1 or core2 have their priority set to 0x3F, except if the thread was created on core1 and whose parent process (if any) has the "Runnable on sleep" ARM11 kernel flag set. Core1 threads with a priority of 0x40 without a parent process have their priority set to 0x3E. Prior to first invoking this handler, the global variable holding UNITINFO != 0 is true, and if there is no LCD fill set at the time kernelpanic is called, kernelpanic fills the top screen with red and the bottom screen with either yellow (if the current process was running under the APPLICATION memregion) or red. Before invoking this handler a second time, kernelpanic wait for the user to hold L+R+Start+Select down.
6	Yes	No	Arguments: u32 what, u64 val UNITINFO needs to be non-zero. If what is 0 or any invalid value, nothing is done. If it is 1, val != 0 is written to the global variable enabling ERR:F-format register dumps on user-mode CPU/VFP exceptions (the VFP exception handler acts as if this variable was always true and works on retail environments). The user handler, stack pointer to use for exception handling, and pointer to use for the exception info structure are contiguously located in either the thread's TLS, or if the handler is NULL, in the main thread's TLS, at offset 0x40. If the specified stack pointer is 1, sp_usr - 0x5c is used instead; if the specified exception info buffer is 1, sp_usr - 0x5c is used instead, and if it is 0, <specified stack> - 0x5c is used (0x5c is the size of the exception info structure that is being pushed). Configured by NS on startup on dev-units (default being 0 on non-debugger/jtag units). If 2, kernelpanic will be called when svcBreak is used by a non-attached process. Configured by NS on startup on dev-units (default being 0 on non-debugger/jtag units). If 3, this changes the scheduling/preemption mode (when no threads are being preempted, otherwise returns error 0xC8A01414), see KResourceLimit for more details.
7	Yes	No	This triggers an MCU (hard) reboot. 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. On New3DS, the kernel disables the additional New3DS cache hw prior to calling the reboot function from the <handler for the KernelSetState-types called via funcptr>.
8	Yes	No	Alternate FIRM launch code-path, with different PXI FIFO word constants. Usually not used. PTM-sysmodule can use this but it's unknown what exactly triggers that in PTM-sysmodule.
9	Yes, implemented at some point after system-version v4.5.	?	Argumens: u64 titleID. When creating a process, if the process has a non-zero TID equal to the parameter above (which is stored in a global variable), then KProcessHwInfo+0x32 ("process is the currently running app") is set to true. Used by NS conditionally based on the contents of the NS CFA.
10	Yes	?	Arguments: u32 config ConfigureNew3DSCPU. Only available for the New_3DS kernel. The actual code for processing this runs under the <handler for the KernelSetState-types called via funcptr>, which runs on all ARM11 cores. Only bit0-1 of the argument are used here. Bit 0 enables higher core clock, and bit 1 enables additional (L2) cache. 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.
2	Unused	This writes the FCRAM memory used by the kernel to out.
25	Unused	This writes the total number of threads which were directly launched by the kernel, to out. No longer exists with some kernel version?
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
0		Returns the amount of executable memory allocated to the process + thread context size + page-rounded size of the external handle table
1		Returns the amount of <unknown> memory allocated to the process + thread context size + page-rounded size of the external handle table
2		Returns the amount of DMA-able (code, data, IO pages, etc.) memory allocated to the process + thread context size + page-rounded size of the external handle table
3		Returns the amount of <unknown> memory allocated to the process + thread context size + page-rounded size of the external handle table
4		Returns the amount handles in use by the process.
5		Returns the highest count of handles that have been open at once by the process
6		Returns *(u32*)(KProcess+0x234) which is always 0
7		Returns 0
8		Returns the maximum number of threads which can be opened by this process (always 0)
9-18	8.0.0-18	This only returns error 0xD8E007ED.
19	Stub: 8.0.0-18. Implementation: 11.3.0-X.	Originally this only returned 0xD8E007ED. Now with v11.3 this returns the memregion for the process: out low u32 = KProcess "Kernel flags from the exheader kernel descriptors" & 0xF00. High out u32 = 0.
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	8.0.0-18. N3DS only.	Returns the maximum amount of VRAM memory allocatable by the process: 0x800000 bytes if the process has already allocated VRAM memory, otherwise 0 (+ error 0xE0E01BF4)
22	8.0.0-18. N3DS only.	Returns the address of the first chunk of VRAM allocated by this process
23	8.0.0-18. N3DS only.	Returns the amount of VRAM allocated by this process (?)

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 for kernel object (not counting the one this SVC adds internally to operate), and also a boolean if it is negative.
2	Unimplemented, returns an uninitialized u64 variable (corresponding to r5-r6, which were not altered outside of userland).
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).

svc 0x59

Implemented with 11.3.0-X. Used with GSP module starting with that version. This always returns 0.

When input_flag is not 0x1, it will use value 0x0 internally. When a state field already matches input_flag, this will immediately return. Otherwise, after this SVC finishes running, it will write input_flag to this state field. GSP module uses 0x0 for APPLICATION-memregionid and 0x1 for non-APPLICATION-memregionid.

This writes "0x100 | <val>" to pdnregbase+0x140, where val depends on input_flag and a kernel state field for APPMEMTYPE.

When input_flag is 0x1 val is fixed:

• Old3DS: 0x3
• New3DS: 0x460

Otherwise, val depends on the kernel APPMEMTYPE state field:

FIRM	APPMEMTYPE	val
Old3DS	2	0x3
Old3DS	3	0x5
Old3DS	4	0x6
Old3DS	Non-value-{2/3/4}	0x7
New3DS	7	0x490
New3DS	Non-value-7	0x4F0

This same register is also initialized during kernel boot starting with 3.0.0-5, with the following values:

• Old3DS: 0x103
• New3DS: 0x550

svc 0x5A

Like what NWM did previously, this one does the following:

 if (in_flag)
    CFG11_WIFICNT |= 1;
 else
    CFG11_WIFICNT &= ~1;

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
0xD8609013	Unknown, probably reslimit related?
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.