thread: Main thread should set thread handle to reg 1.

src/core/hle/kernel/thread.cpp

@@ -490,7 +490,8 @@ void Thread::BoostPriority(u32 priority) {
     current_priority = priority;
 }
 
-SharedPtr<Thread> SetupMainThread(VAddr entry_point, u32 priority, SharedPtr<Process> owner_process) {
+SharedPtr<Thread> SetupMainThread(VAddr entry_point, u32 priority,
+                                  SharedPtr<Process> owner_process) {
     // Setup page table so we can write to memory
     SetCurrentPageTable(&Kernel::g_current_process->vm_manager.page_table);
 
@@ -500,6 +501,8 @@ SharedPtr<Thread> SetupMainThread(VAddr entry_point, u32 priority, SharedPtr<Pro
 
     SharedPtr<Thread> thread = std::move(thread_res).Unwrap();
 
+    // Register 1 must be a handle to the main thread
+    thread->context.cpu_registers[1] = Kernel::g_handle_table.Create(thread).Unwrap();
     thread->context.fpscr =
         FPSCR_DEFAULT_NAN | FPSCR_FLUSH_TO_ZERO | FPSCR_ROUND_TOZERO | FPSCR_IXC; // 0x03C00010