fork return value

kernel/arch/core_ring.cc

@@ -26,7 +26,7 @@ void switchToUsermode(void *stackpointer, void *kickoff,
             "pushq %[user_eflags] \n" \
             "pushq %[user_code] \n" \
             "pushq %[user_function] \n" \
-            "mov %[user_parameter], %%rdi\n" \
+            "mov %[user_parameter], %%rax\n" \
             "iretq \n" \
             : \
             : [user_data] "r"((uint64_t)user_ds), 

kernel/syscall/skeleton.cc

@@ -296,10 +296,14 @@ int fork(Vault &vault, InterruptContext *user_context) {
     copy_stack(parent, child);
 
     child->StackPointer.user = (void*)user_context->sp;
+    vault.thread_list[child->id] = child;
 
+    //return parent pid to child
+	prepareContext(child->StackPointer.isr, child->context, Thread::kickoff, reinterpret_cast<uintptr_t>(child), parent->id, 0);
     vault.scheduler.ready(child);
     
-    return 0;
+    // return child pid to parent
+    return child->id;
 }
 
 

kernel/thread/thread.cc

@@ -16,13 +16,12 @@ extern pagetable_t identity_table;
 void Thread::kickoff(uintptr_t param1, uintptr_t param2, uintptr_t param3) {
 	Thread *thread = reinterpret_cast<Thread *>(param1);
 	assert(thread != nullptr && "Kickoff got nullptr pointer to Thread");
-	(void)param2;  // will be used later
 	(void)param3;  // will be used later
 	// The core must have entered level 1/2 to cause a thread to be scheduled.
 	Guard::leave();
 
 	if(!thread->isKernel)
-		Core::Ring::switchToUsermode(thread->StackPointer.user, thread->start, 0);
+		Core::Ring::switchToUsermode(thread->StackPointer.user, thread->start, (void*)param2);
 	else
 		if(thread->start == nullptr)
 			thread->action();

kernel/thread/thread.h

@@ -75,11 +75,11 @@ class Thread {
 	 *  \param param3 Third parameter (will be used later)
 	 *
 	 */
-	static void kickoff(uintptr_t param1, uintptr_t param2, uintptr_t param3);
 
 	static void kickoffUsermode (Thread *object);
 	void map_app(void* code_paddr, uint16_t code_page_num, void* stack_vaddr, uint16_t stack_page_num);
    public:
+	static void kickoff(uintptr_t param1, uintptr_t param2, uintptr_t param3);
 	struct{
 		void* user;
 		void* isr;

user/app1/appl.cc

@@ -45,19 +45,26 @@ extern "C" void main() {
 
 	//sys_test(1,2,3,4,5);
 
-	fork();
+	uint8_t ret = fork();
+	//ret = fork();
 
 	unsigned id = sys_getpid();
+
 	char text[] = "appX";
 	text[3] = 0x30+id;
-	write(1, text, sizeof(text), 0, (int)id);
+	write(1, text, strlen(text), 0, (int)id);
+
+	char msg[] = "forked pid:  ";
+	msg[12] = 0x30+ret;
+	write(1, msg, strlen(msg), 6, (int)id);
+
 	uint8_t cnt = 0;
 
 	while(1){
 		cnt = (cnt+1)%100;
 		char msg[12];
 		char* num = itoa(cnt, msg);
-		write(1, num, strlen(num), 10, (int)id);
+		write(1, num, strlen(num), 25, (int)id);
 		sleep(100);
 	}