AnyPS5/docs/dev/debt/libSceHmd2.md

# libSceHmd2 technical debt

### Silent stubs

- [libSceHmd2](../../../core/libs/prx/libSceHmd2/Export.cpp) has no PS VR2 runtime: `sceHmd2Initialize` returns libSceHmd's `UNSUPPORTED_FEATURE` (0x81110016) for any param, so the other calls answer as before initialization and `sceHmd2Open` returns `NotInitialized` (0x8a720002). These results are restored from the behaviour before #7323 and are not measured on hardware: firmware 13.20's libSceHmd2, with the `/dev/hmd2_cmd` state measured on a retail PS5 with no headset connected (connected flag 0, status 2, user -1), initializes, returns a handle from `sceHmd2Open` and reports `NotDetected`, which the code past the initialization check models but no title reaches. PPSA01317 passes a pointer to 16 zeroed bytes, only tests the result for non-zero and then skips its VR set-up; with initialization succeeding it stopped on `sceHmd2ReprojectionQueryBufferSizeAlign` (#6350). That export, `sceHmd2ReprojectionQueryDisplayBufferSizeAlign` and `sceHmd2ReprojectionQuerySeeThroughBufferSizeAlign` stay unimplemented and throw pending console measurements of their sizes and alignments. The other reprojection and gaze exports throw, and [libSceVrTracker2](../../../core/libs/prx/libSceVrTracker2/Export.cpp) never initializes

### Unknown function info

- PPSA09030 imports from its `Media/Plugins/psvr2.prx` declared without parameters, signatures unknown, added without an implementation because the title fails to load the plugin without them: [sceHmd2ReprojectionGetStatus](../../../core/libs/prx/libSceHmd2/Export.cpp) (libSceHmd2)
- [sceHmd2Open](../../../core/libs/prx/libSceHmd2/Export.cpp) (libSceHmd2) - the handle is the value the console's driver returned to the first open; titles built with an SDK before 7.00 may open for any user, and the firmware's `sceMbusAddHandleByUserId` result for a user other than the initial one is unknown, so that case throws. 0x8a720006 for a second open is named `AlreadyOpened` from its use
- [sceHmd2SetVibration](../../../core/libs/prx/libSceHmd2/Export.cpp) (libSceHmd2) - the second parameter is checked against 25 only while a headset is connected; its name and unit are unknown. The field of view member names are assumed: of the firmware's default tangents the first is the widest and the last two are equal
- PPSA01317 imports declared without parameters, signatures unknown: the [libSceHmd2](../../../core/libs/prx/libSceHmd2/Export.cpp) exports that throw and the remaining [libSceVrTracker2](../../../core/libs/prx/libSceVrTracker2/Export.cpp) exports. Names from the aerolib NID list
- PPSA15878 imports declared without parameters, signatures unknown: the [libSceHmd2](../../../core/libs/prx/libSceHmd2/Export.cpp) reprojection and gaze exports, `sceVrTracker2Finalize`, `sceVrTracker2GetPlayAreaOrientedBoundingBox` and `sceVrTracker2LocateCoordinateSystem` in [libSceVrTracker2](../../../core/libs/prx/libSceVrTracker2/Export.cpp), and the `scePadVrController` trigger effect exports in [libScePad](../../../core/libs/prx/libScePad/Export.cpp). Names from the aerolib NID list
- [libSceHmd2 gaze and reprojection exports](../../../core/libs/prx/libSceHmd2/Export.cpp) (libSceHmd2) - `sceHmd2GazeGetCalibrationData`, `sceHmd2GazeGetCalibrationDataMaxSize`, `sceHmd2ReprojectionClearUserEventEnd`, `sceHmd2ReprojectionClearUserEventStart`, `sceHmd2ReprojectionGetCurrentOutput`, `sceHmd2ReprojectionSetUserEventEnd`, `sceHmd2ReprojectionSetUserEventStart`, `sceHmd2GazeActivateGazeTracking`, `sceHmd2GazeGetDeviceStatus`, `sceHmd2GazeGetUserCalibrationStatus`, `sceHmd2GazeInsertRawDataWithHandle`, `sceHmd2GazeSetEnabledEye`, `sceHmd2GazeSetUserCalibrationData`, `sceHmd2GazeSetUserCalibrationPoint`, `sceHmd2GazeStartUserCalibration`, `sceHmd2GazeStopUserCalibration`, `sceHmd2ReprojectionSeeThroughDraw`, `sceHmd2ReprojectionSeeThroughIC`, `sceHmd2ReprojectionVideoOutEq`, `sceHmd2ReprojectionWaitShader`, `sceHmd2SeeThroughCallbackGetPoseDataFunc`, `sceHmd2GazeObjectSelectionGetSelectedObject`, `sceHmd2GazeObjectSelectionInitialize`, `sceHmd2GazeObjectSelectionQueryMemory`, `sceHmd2GazeObjectSelectionTerminate`, `sceHmd2ReprojectionClear`, `sceHmd2ReprojectionSet`, `sceHmd2ReprojectionSetEventGpuEnd`, `sceHmd2ReprojectionSetEventGpuStart`, `sceHmd2RpeorjectionSetParam`, `sceHmd2SetFieldOfView`, `sceHmd2SetIpdOffset` are declared without parameters from the firmware export database (aerolib.csv); their guest signatures are unverified on hardware and every call throws
- [sceHmd2InternalSetPortStatus](../../../core/libs/prx/libSceHmd2/Export.cpp) (libSceHmd2) - unknown signature
- [sceHmd2InternalLedDetectorStartBySlot](../../../core/libs/prx/libSceHmd2/Export.cpp) (libSceHmd2) - unknown signature
- [sceHmd2InternalImageStartBySlot](../../../core/libs/prx/libSceHmd2/Export.cpp) (libSceHmd2) - unknown signature
- [sceHmd2InternalSetPortConnection](../../../core/libs/prx/libSceHmd2/Export.cpp) (libSceHmd2) - unknown signature
- [sceHmd2InternalSetCameraSeeThroughMode](../../../core/libs/prx/libSceHmd2/Export.cpp) (libSceHmd2) - unknown signature
- [sceHmd2InternalSetFakeLensSeparationDistance](../../../core/libs/prx/libSceHmd2/Export.cpp) (libSceHmd2) - unknown signature
- [sceHmd2InternalDfuSend](../../../core/libs/prx/libSceHmd2/Export.cpp) (libSceHmd2) - unknown signature
- [sceHmd2InternalLedDetectorOpenBySlot](../../../core/libs/prx/libSceHmd2/Export.cpp) (libSceHmd2) - unknown signature
- [sceHmd2InternalImageOpenBySlot](../../../core/libs/prx/libSceHmd2/Export.cpp) (libSceHmd2) - unknown signature
- [sceHmd2InternalLedDetectorStopBySlot](../../../core/libs/prx/libSceHmd2/Export.cpp) (libSceHmd2) - unknown signature
- [sceHmd2InternalSetDeviceConnection](../../../core/libs/prx/libSceHmd2/Export.cpp) (libSceHmd2) - unknown signature
- [sceHmd2InternalLedDetectorCloseBySlot](../../../core/libs/prx/libSceHmd2/Export.cpp) (libSceHmd2) - unknown signature
- [sceHmd2InternalSetSidetone](../../../core/libs/prx/libSceHmd2/Export.cpp) (libSceHmd2) - unknown signature
- [sceHmd2InternalGetDeviceId](../../../core/libs/prx/libSceHmd2/Export.cpp) (libSceHmd2) - unknown signature
- [sceHmd2InternalSetBrightness](../../../core/libs/prx/libSceHmd2/Export.cpp) (libSceHmd2) - unknown signature
- [sceHmd2InternalImageStopBySlot](../../../core/libs/prx/libSceHmd2/Export.cpp) (libSceHmd2) - unknown signature
- [sceHmd2InternalSetVibrationMode](../../../core/libs/prx/libSceHmd2/Export.cpp) (libSceHmd2) - unknown signature
- [sceHmd2InternalGetVr2dData](../../../core/libs/prx/libSceHmd2/Export.cpp) (libSceHmd2) - unknown signature
- [sceHmd2InternalImageCloseBySlot](../../../core/libs/prx/libSceHmd2/Export.cpp) (libSceHmd2) - unknown signature

### Functional

- [sceHmd2Initialize](../../../core/libs/prx/libSceHmd2/Export.cpp) (libSceHmd2) - the firmware also fails with 0x8a72001f when `sceKernelGetAppInfo` fails and with 0x8a72000a for some applications, depending on app info fields at 0x2c, 0x4b and 0x4d whose meaning is unknown, and then calls `sceMbusInit`; none of this is modelled
- [sceHmd2ReprojectionQueryDisplayBufferSizeAlign, sceHmd2ReprojectionQuerySeeThroughBufferSizeAlign, sceHmd2ReprojectionGetMirroringDisplayBufferSizeAlign and sceHmd2ReprojectionGetMirroringWorkMemorySizeAlign](../../../core/libs/prx/libSceHmd2/Export.cpp) (libSceHmd2) - each returns a `{uint64 size, uint64 alignment}` pair in RAX:RDX; the values were measured on a retail PS5 (firmware 13.60) with no PS VR2 headset from a homebrew payload that loaded `libSceHmd2.sprx` without initializing it, and stayed the same for every argument tried; `sceHmd2ReprojectionQueryBufferSizeAlign` measured there returns 0x100828 and 0x100 for every argument, including the 2, 0xAF and 1 that PPSA05666 passes. They are assumed not to depend on initialization or on a connected headset, and their parameters are unknown