Properly using XapiThreadStartup routines, if present.

src/xenia/cpu/processor.cc

@@ -234,6 +234,17 @@ uint64_t Processor::Execute(ThreadState* thread_state, uint32_t address,
   return ppc_state->r[3];
 }
 
+uint64_t Processor::Execute(ThreadState* thread_state, uint32_t address,
+                            uint64_t arg0, uint64_t arg1) {
+  xe_ppc_state_t* ppc_state = thread_state->ppc_state();
+  ppc_state->r[3] = arg0;
+  ppc_state->r[4] = arg1;
+  if (Execute(thread_state, address)) {
+    return 0xDEADBABE;
+  }
+  return ppc_state->r[3];
+}
+
 FunctionSymbol* Processor::GetFunction(uint32_t address) {
   // Attempt to grab the function symbol from the global lookup table.
   FunctionSymbol* fn_symbol = sym_table_->GetFunction(address);

src/xenia/cpu/processor.h

@@ -58,6 +58,8 @@ public:
   void DeallocThread(ThreadState* thread_state);
   int Execute(ThreadState* thread_state, uint32_t address);
   uint64_t Execute(ThreadState* thread_state, uint32_t address, uint64_t arg0);
+  uint64_t Execute(ThreadState* thread_state, uint32_t address,
+                   uint64_t arg0, uint64_t arg1);
   sdb::FunctionSymbol* GetFunction(uint32_t address);
   void* GetFunctionPointer(uint32_t address);
 

src/xenia/kernel/modules/xboxkrnl/objects/xthread.cc

@@ -254,17 +254,20 @@ X_STATUS XThread::PlatformExit(int exit_code) {
 #endif  // WIN32
 
 void XThread::Execute() {
-  // Run XapiThreadStartup first, if present.
+  // If a XapiThreadStartup value is present, we use that as a trampoline.
+  // Otherwise, we are a raw thread.
   if (creation_params_.xapi_thread_startup) {
-    XELOGE("xapi_thread_startup not implemented");
+    kernel_state()->processor()->Execute(
-  }
+        thread_state_,
-
+        creation_params_.xapi_thread_startup,
+        creation_params_.start_address, creation_params_.start_context);
+  } else {
     // Run user code.
     int exit_code = (int)kernel_state()->processor()->Execute(
         thread_state_,
         creation_params_.start_address, creation_params_.start_context);
-
     // If we got here it means the execute completed without an exit being called.
     // Treat the return code as an implicit exit code.
     Exit(exit_code);
+  }
 }