write kernel sp to tss in dispatcher

kernel/thread/thread.h

@@ -28,7 +28,7 @@ class Thread {
 	/*! \brief pointer to the next element of the readylist
 	 */
 	Thread* queue_link;
-	bool isKernel = true;
+	bool isKernel;
 	void* start;
 
 	friend class Queue<Thread>;
@@ -38,11 +38,6 @@ class Thread {
 	alignas(16) char reserved_stack_space_user[STACK_SIZE];
 	alignas(16) char reserved_stack_space_isr[STACK_SIZE];
 
-	struct{
-		void* user;
-		void* isr;
-	} StackPointer;
-
    protected:
 	/*! \brief Context of the thread, used for saving and restoring the register
 	 * values when context switching.
@@ -70,6 +65,11 @@ class Thread {
 	static void kickoffUsermode (Thread *object);
 
    public:
+	struct{
+		void* user;
+		void* isr;
+	} StackPointer;
+
 	/*! \brief Unique thread id */
 	const size_t id;