3 files changed, 45 insertions, 8 deletions
diff --git a/src/core/hle/service/apt/apt.cpp b/src/core/hle/service/apt/apt.cpp
index 4c6156345..2f7362748 100644
--- a/src/core/hle/service/apt/apt.cpp
+++ b/src/core/hle/service/apt/apt.cpp
@@ -65,6 +65,7 @@ union AppletAttributes {
     u32 raw;
 
     BitField<0, 3, u32> applet_pos;
+    BitField<29, 1, u32> is_home_menu;
 
     AppletAttributes() : raw(0) {}
     AppletAttributes(u32 attributes) : raw(attributes) {}
@@ -158,6 +159,11 @@ static AppletSlotData* GetAppletSlotData(AppletAttributes attributes) {
     if (slot == AppletSlot::Error)
         return nullptr;
 
+    // The Home Menu is a system applet, however, it has its own applet slot so that it can run
+    // concurrently with other system applets.
+    if (slot == AppletSlot::SystemApplet && attributes.is_home_menu)
+        return &applet_slots[static_cast<size_t>(AppletSlot::HomeMenu)];
+
     return &applet_slots[static_cast<size_t>(slot)];
 }
 
@@ -197,6 +203,19 @@ void Initialize(Service::Interface* self) {
     rb.Push(RESULT_SUCCESS);
     rb.PushCopyHandles(Kernel::g_handle_table.Create(slot_data->notification_event).Unwrap(),
                        Kernel::g_handle_table.Create(slot_data->parameter_event).Unwrap());
+
+    if (slot_data->applet_id == AppletId::Application ||
+        slot_data->applet_id == AppletId::HomeMenu) {
+        // Initialize the APT parameter to wake up the application.
+        next_parameter.emplace();
+        next_parameter->signal = static_cast<u32>(SignalType::Wakeup);
+        next_parameter->sender_id = static_cast<u32>(AppletId::None);
+        next_parameter->destination_id = app_id;
+        // Not signaling the parameter event will cause the application (or Home Menu) to hang
+        // during startup. In the real console, it is usually the Kernel and Home Menu who cause NS
+        // to signal the HomeMenu and Application parameter events, respectively.
+        slot_data->parameter_event->Signal();
+    }
 }
 
 static u32 DecompressLZ11(const u8* in, u8* out) {
@@ -757,6 +776,20 @@ void PrepareToStartLibraryApplet(Service::Interface* self) {
     LOG_DEBUG(Service_APT, "called applet_id=%08X", applet_id);
 }
 
+void PrepareToStartNewestHomeMenu(Service::Interface* self) {
+    IPC::RequestParser rp(Kernel::GetCommandBuffer(), 0x1A, 0, 0); // 0x1A0000
+    IPC::RequestBuilder rb = rp.MakeBuilder(1, 0);
+
+    // TODO(Subv): This command can only be called by a System Applet (return 0xC8A0CC04 otherwise).
+
+    // This command must return an error when called, otherwise the Home Menu will try to reboot the
+    // system.
+    rb.Push(ResultCode(ErrorDescription::AlreadyExists, ErrorModule::Applet,
+                       ErrorSummary::InvalidState, ErrorLevel::Status));
+
+    LOG_DEBUG(Service_APT, "called");
+}
+
 void PreloadLibraryApplet(Service::Interface* self) {
     IPC::RequestParser rp(Kernel::GetCommandBuffer(), 0x16, 1, 0); // 0x160040
     AppletId applet_id = static_cast<AppletId>(rp.Pop<u32>());
@@ -1041,12 +1074,6 @@ void Init() {
         slot_data.parameter_event =
             Kernel::Event::Create(Kernel::ResetType::OneShot, "APT:Parameter");
     }
-
-    // Initialize the parameter to wake up the application.
-    next_parameter.emplace();
-    next_parameter->signal = static_cast<u32>(SignalType::Wakeup);
-    next_parameter->destination_id = static_cast<u32>(AppletId::Application);
-    applet_slots[static_cast<size_t>(AppletSlot::Application)].parameter_event->Signal();
 }
 
 void Shutdown() {
diff --git a/src/core/hle/service/apt/apt.h b/src/core/hle/service/apt/apt.h
index 96b28b438..7b79e1f3e 100644
--- a/src/core/hle/service/apt/apt.h
+++ b/src/core/hle/service/apt/apt.h
@@ -420,6 +420,16 @@ void GetAppCpuTimeLimit(Service::Interface* self);
 void PrepareToStartLibraryApplet(Service::Interface* self);
 
 /**
+ * APT::PrepareToStartNewestHomeMenu service function
+ *  Inputs:
+ *      0 : Command header [0x001A0000]
+ *  Outputs:
+ *      0 : Return header
+ *      1 : Result of function
+ */
+void PrepareToStartNewestHomeMenu(Service::Interface* self);
+
+/**
  * APT::PreloadLibraryApplet service function
  *  Inputs:
  *      0 : Command header [0x00160040]
diff --git a/src/core/hle/service/apt/apt_s.cpp b/src/core/hle/service/apt/apt_s.cpp
index ec5668d05..fe1d21fff 100644
--- a/src/core/hle/service/apt/apt_s.cpp
+++ b/src/core/hle/service/apt/apt_s.cpp
@@ -17,7 +17,7 @@ const Interface::FunctionInfo FunctionTable[] = {
     {0x00060040, GetAppletInfo, "GetAppletInfo"},
     {0x00070000, nullptr, "GetLastSignaledAppletId"},
     {0x00080000, nullptr, "CountRegisteredApplet"},
-    {0x00090040, nullptr, "IsRegistered"},
+    {0x00090040, IsRegistered, "IsRegistered"},
     {0x000A0040, nullptr, "GetAttribute"},
     {0x000B0040, InquireNotification, "InquireNotification"},
     {0x000C0104, nullptr, "SendParameter"},
@@ -34,7 +34,7 @@ const Interface::FunctionInfo FunctionTable[] = {
     {0x00170040, nullptr, "FinishPreloadingLibraryApplet"},
     {0x00180040, PrepareToStartLibraryApplet, "PrepareToStartLibraryApplet"},
     {0x00190040, nullptr, "PrepareToStartSystemApplet"},
-    {0x001A0000, nullptr, "PrepareToStartNewestHomeMenu"},
+    {0x001A0000, PrepareToStartNewestHomeMenu, "PrepareToStartNewestHomeMenu"},
     {0x001B00C4, nullptr, "StartApplication"},
     {0x001C0000, nullptr, "WakeupApplication"},
     {0x001D0000, nullptr, "CancelApplication"},