Lifecycle: drain asynchronous boot before shutdown

Join the loader before dismantling guest memory, filesystems or graphics state. A failed loader has already shut down the CPU, so skip duplicate cleanup and still complete lifecycle teardown. Clear libretro pending boot and deferred state buffers on unload/reset. This drains an in-progress load; it does not interrupt a blocking backend read.

Core/System.cpp

@@ -855,17 +855,25 @@ BootState PollBootState() {
 }
 
 void PSP_Shutdown(bool success) {
+	// Only the lifecycle owner calls this; the loader uses CPU_Shutdown on
+	// failure. Finish its accesses before destroying memory or filesystem state.
+	if (g_loadingThread.joinable()) {
+		g_loadingThread.join();
+		Core_NotifyLifecycle(CoreLifecycle::START_COMPLETE);
+	}
+
 	// Do nothing if we never inited.
 	if (GetBootState() == BootState::Off) {
 		ERROR_LOG(Log::Loader, "Unexpected PSP_Shutdown");
 		return;
 	}
 
-	_assert_(GetBootState() != BootState::Failed);
+	// A failed loader already shut its CPU state down. Do not do that twice.
+	const bool cpuInitialized = GetBootState() != BootState::Failed;
 
 	Core_Stop();
 
-	if (g_Config.bFuncHashMap) {
+	if (cpuInitialized && g_Config.bFuncHashMap) {
 		MIPSAnalyst::StoreHashMap();
 	}
 
@@ -876,7 +884,8 @@ void PSP_Shutdown(bool success) {
 
 	Core_NotifyLifecycle(CoreLifecycle::STOPPING);
 
-	CPU_Shutdown(success);
+	if (cpuInitialized)
+		CPU_Shutdown(success);
 	GPU_Shutdown();
 	g_paramSFO.Clear();
 	g_paramSFORaw.Clear();
@@ -890,7 +899,7 @@ void PSP_Shutdown(bool success) {
 
 	Core_NotifyLifecycle(CoreLifecycle::STOPPED);
 
-	if (success) {
+	if (success || !cpuInitialized) {
 		SetBootState(BootState::Off);
 	}
 

libretro/libretro.cpp

@@ -1532,6 +1532,11 @@ void retro_unload_game(void) {
    }
 
 	PSP_Shutdown(true);
+	g_pendingBoot = false;
+	g_bootErrorString.clear();
+	free(unserialize_data);
+	unserialize_data = nullptr;
+	unserialize_size = 0;
 	g_VFS.Clear();
 
 	delete ctx;
@@ -1546,6 +1551,10 @@ void retro_reset(void) {
       Libretro::EmuThreadStop();
 
    PSP_Shutdown(true);
+   g_pendingBoot = false;
+   free(unserialize_data);
+   unserialize_data = nullptr;
+   unserialize_size = 0;
 
    if (BootState::Complete != PSP_Init(PSP_CoreParameter(), &g_bootErrorString)) {
       ERROR_LOG(Log::Boot, "%s", g_bootErrorString.c_str());