Services

Services are an abstraction of ports and are the commonly used way of inter-process communication outside of the kernel. While handles of regular ports are retrieved from SVC(svcConnectToPort), service handles are retrieved through the port srv: ("service manager").

When a service is registered, svcCreatePort is used without a port-name. This means that the port is inaccessible via the port SVCs outside of sm-module. See below for getting a session handle for sending commands to services.

Processes with PID less than or equal to the number of NATIVE_FIRM built-in modules (fs, sm, pm, pxi, ldr) have access to all services. This value is obtained from svcGetSystemInfo.

Attempting to use srvGetServiceSession with a service that the process has access to when that service isn't registered, results in svcSendSyncRequest never returning(the exact cause is unknown).

Service Manager Port "srv:"

Command Header	Description
0x00010002	Initialize
0x00020000	GetProcSemaphore() (the handle from this gets signaled when notifications for this process gets triggered)
0x00030100	RegisterService(8-byte servicename, u32 strlen, u32 max_sessions)
0x000400C0	UnregisterService(8-byte servicename, u32 strlen)
0x00050100	GetServiceSession(8-byte servicename, u32 strlen, u32 flags) Flags bit0: if not set, return port-handle instead of session-handle(from svcCreateSessionToPort) when session-handle unavailable (max sessions/timeout?).
0x000600C2	RegisterPort(8-byte servicename, u32 strlen, Handle client_port)
0x000700C0	UnregisterPort(8-byte servicename, u32 strlen)
0x00080100	GetPort(8-byte servicename, u32 strlen, u32 flags). Flags bit0: return 0 instead of port handle if port was found.
0x00090040	Subscribe(u32 notification_id). This enables the specified notificationID for the current process.
0x000A0040	Unsubscribe(u32 notification_id). This disables the specified notificationID for the current process.
0x000B0000	ReceiveNotification() This returns the notificationID which was triggered, if any(see GetProcSemaphore).
0x000C0080	PublishToSubscriber(u32 notification_id, u32 flag). This fires an notification. Bit0: only fire if not already fired, bit1: return error if error happens, else it always returns 0.
0x000D0040	This can fire notificationIDs and return the number of fired notificationID
0x000E00C0	HasAccessToService(8-byte servicename, u32 strlen). Returns 1 if your process has access to the service.

Service Manager Process-Manager Port "srv:pm"

Command Header, prior to 7.0.0-13	Description
0x04030082	RegisterProcess (u32 procid, u32 wordsz, ((wordsz<<16) | 2), serviceaccesscontrol*).
0x04040040	UnregisterProcess (u32 procid).

The Register command registers a process with the service-manager, which includes registering the serviceaccesscontrol for the process which normally originates from the exheader.

Prior to to 7.0.0-13, the commands listed for "srv:" were also accessible under this port with the same command-headers. Starting with 7.0.0-13, the "srv:pm" port was changed to a service. With this change, commandIDs for these commands were changed. "srv:pm" was originally vulnerable, this was fixed with 7.0.0-13, see here. Originally any process could use "srv:pm", however starting with 7.0.0-13 only the built-in NATIVE_FIRM sysmodules have access to it. The only system title which uses "srv:pm" is the Process Manager.

Notifications

ID	Description
0x100	This indicates that all processes must terminate: power-off, reboot, or FIRM-launch.
0x105	This indicates that the system is entering sleep mode.
0x108	error at boot?
0x202	POWER button pressed
0x204	This indicates that the HOME button was pressed.
0x205	HOME button pressed
0x207	SD card inserted
0x208	Game cartridge inserted
0x209	SD card removed
0x20A	Game cartridge removed
0x20B	Game cartridge inserted or removed