4 files changed, 57 insertions, 22 deletions
diff --git a/src/core/core.cpp b/src/core/core.cpp
index 5d8a61b3a..5893a86bf 100644
--- a/src/core/core.cpp
+++ b/src/core/core.cpp
@@ -4,6 +4,7 @@
 
 #include <array>
 #include <atomic>
+#include <exception>
 #include <memory>
 #include <utility>
 
@@ -84,8 +85,6 @@ FileSys::StorageId GetStorageIdForFrontendSlot(
 
 } // Anonymous namespace
 
-/*static*/ System System::s_instance;
-
 FileSys::VirtualFile GetGameFileFromPath(const FileSys::VirtualFilesystem& vfs,
                                          const std::string& path) {
     // To account for split 00+01+etc files.
@@ -425,6 +424,20 @@ struct System::Impl {
 System::System() : impl{std::make_unique<Impl>(*this)} {}
 System::~System() = default;
 
+System& System::GetInstance() {
+    if (!s_instance) {
+        throw std::runtime_error("Using System instance before its initialization");
+    }
+    return *s_instance;
+}
+
+void System::InitializeGlobalInstance() {
+    if (s_instance) {
+        throw std::runtime_error("Reinitializing Global System instance.");
+    }
+    s_instance = std::unique_ptr<System>(new System);
+}
+
 CpuManager& System::GetCpuManager() {
     return impl->cpu_manager;
 }
diff --git a/src/core/core.h b/src/core/core.h
index cd9af0c07..f9116ebb6 100644
--- a/src/core/core.h
+++ b/src/core/core.h
@@ -120,9 +120,9 @@ public:
      * Gets the instance of the System singleton class.
      * @returns Reference to the instance of the System singleton class.
      */
-    [[deprecated("Use of the global system instance is deprecated")]] static System& GetInstance() {
-        return s_instance;
-    }
+    [[deprecated("Use of the global system instance is deprecated")]] static System& GetInstance();
+
+    static void InitializeGlobalInstance();
 
     /// Enumeration representing the return values of the System Initialize and Load process.
     enum class ResultStatus : u32 {
@@ -393,7 +393,7 @@ private:
     struct Impl;
     std::unique_ptr<Impl> impl;
 
-    static System s_instance;
+    inline static std::unique_ptr<System> s_instance{};
 };
 
 } // namespace Core
diff --git a/src/core/hle/kernel/kernel.cpp b/src/core/hle/kernel/kernel.cpp
index 8673384ee..8fdab44e4 100644
--- a/src/core/hle/kernel/kernel.cpp
+++ b/src/core/hle/kernel/kernel.cpp
@@ -261,20 +261,23 @@ struct KernelCore::Impl {
         current_process = process;
     }
 
-    /// Creates a new host thread ID, should only be called by GetHostThreadId
-    u32 AllocateHostThreadId(std::optional<std::size_t> core_id) {
-        if (core_id) {
-            // The first for slots are reserved for CPU core threads
-            ASSERT(*core_id < Core::Hardware::NUM_CPU_CORES);
-            return static_cast<u32>(*core_id);
-        } else {
-            return next_host_thread_id++;
+    static inline thread_local u32 host_thread_id = UINT32_MAX;
+
+    /// Gets the host thread ID for the caller, allocating a new one if this is the first time
+    u32 GetHostThreadId(std::size_t core_id) {
+        if (host_thread_id == UINT32_MAX) {
+            // The first four slots are reserved for CPU core threads
+            ASSERT(core_id < Core::Hardware::NUM_CPU_CORES);
+            host_thread_id = static_cast<u32>(core_id);
         }
+        return host_thread_id;
     }
 
     /// Gets the host thread ID for the caller, allocating a new one if this is the first time
-    u32 GetHostThreadId(std::optional<std::size_t> core_id = std::nullopt) {
-        const thread_local auto host_thread_id{AllocateHostThreadId(core_id)};
+    u32 GetHostThreadId() {
+        if (host_thread_id == UINT32_MAX) {
+            host_thread_id = next_host_thread_id++;
+        }
         return host_thread_id;
     }
 
diff --git a/src/core/hle/service/am/applets/applet_error.cpp b/src/core/hle/service/am/applets/applet_error.cpp
index ef6854d62..36a4aa9cd 100644
--- a/src/core/hle/service/am/applets/applet_error.cpp
+++ b/src/core/hle/service/am/applets/applet_error.cpp
@@ -16,6 +16,30 @@
 
 namespace Service::AM::Applets {
 
+struct ErrorCode {
+    u32 error_category{};
+    u32 error_number{};
+
+    static constexpr ErrorCode FromU64(u64 error_code) {
+        return {
+            .error_category{static_cast<u32>(error_code >> 32)},
+            .error_number{static_cast<u32>(error_code & 0xFFFFFFFF)},
+        };
+    }
+
+    static constexpr ErrorCode FromResultCode(ResultCode result) {
+        return {
+            .error_category{2000 + static_cast<u32>(result.module.Value())},
+            .error_number{result.description.Value()},
+        };
+    }
+
+    constexpr ResultCode ToResultCode() const {
+        return ResultCode{static_cast<ErrorModule>(error_category - 2000), error_number};
+    }
+};
+static_assert(sizeof(ErrorCode) == 0x8, "ErrorCode has incorrect size.");
+
 #pragma pack(push, 4)
 struct ShowError {
     u8 mode;
@@ -76,12 +100,7 @@ void CopyArgumentData(const std::vector<u8>& data, T& variable) {
 }
 
 ResultCode Decode64BitError(u64 error) {
-    const auto description = (error >> 32) & 0x1FFF;
-    auto module = error & 0x3FF;
-    if (module >= 2000)
-        module -= 2000;
-    module &= 0x1FF;
-    return {static_cast<ErrorModule>(module), static_cast<u32>(description)};
+    return ErrorCode::FromU64(error).ToResultCode();
 }
 
 } // Anonymous namespace