diff --git a/fork.c(detailed) b/fork.c(detailed)
new file mode 100644
index 0000000..4672ec5
--- /dev/null
+++ b/fork.c(detailed)
@@ -0,0 +1,256 @@
+/*
+ *  linux/kernel/fork.c
+ *
+ *  (C) 1991  Linus Torvalds
+ */
+
+ /*
+  *  'fork.c' contains the help-routines for the 'fork' system call
+  * (see also system_call.s), and some misc functions ('verify_area').
+  * Fork is rather simple, once you get the hang of it, but the memory
+  * management can be a bitch. See 'mm/mm.c': 'copy_page_tables()'
+  */
+#include <errno.h>
+
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <asm/segment.h>
+#include <asm/system.h>
+  /*****************************/
+#include <unistd.h>
+/*****************************/
+
+extern void write_verify(unsigned long address);
+
+long last_pid = 0;
+
+void verify_area(void* addr, int size)
+{
+	unsigned long start;
+
+	start = (unsigned long)addr;
+	size += start & 0xfff;
+	start &= 0xfffff000;
+	start += get_base(current->ldt[2]);
+	while (size > 0) {
+		size -= 4096;
+		write_verify(start);
+		start += 4096;
+	}
+}
+
+int copy_mem(int nr, struct task_struct* p)
+{
+	unsigned long old_data_base, new_data_base, data_limit;
+	unsigned long old_code_base, new_code_base, code_limit;
+
+	code_limit = get_limit(0x0f);
+	data_limit = get_limit(0x17);
+	old_code_base = get_base(current->ldt[1]);
+	old_data_base = get_base(current->ldt[2]);
+	if (old_data_base != old_code_base)
+		panic("We don't support separate I&D");
+	if (data_limit < code_limit)
+		panic("Bad data_limit");
+	new_data_base = new_code_base = nr * 0x4000000;
+	p->start_code = new_code_base;
+	set_base(p->ldt[1], new_code_base);
+	set_base(p->ldt[2], new_data_base);
+	if (copy_page_tables(old_data_base, new_data_base, data_limit)) {
+		printk("free_page_tables: from copy_mem\n");
+		free_page_tables(new_data_base, data_limit);
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+/*
+ *  Ok, this is the main fork-routine. It copies the system process
+ * information (task[nr]) and sets up the necessary registers. It
+ * also copies the data segment in it's entirety.
+ */
+int copy_process(int nr, long ebp, long edi, long esi, long gs, long none,
+	long ebx, long ecx, long edx,
+	long fs, long es, long ds,
+	long eip, long cs, long eflags, long esp, long ss)
+{
+	struct task_struct* p;
+	int i;
+	struct file* f;
+
+	p = (struct task_struct*)get_free_page();
+	if (!p)
+		return -EAGAIN;
+	task[nr] = p;
+	__asm__ volatile ("cld");
+	*p = *current;	/* NOTE! this doesn't copy the supervisor stack */
+	p->state = TASK_UNINTERRUPTIBLE;
+	p->pid = last_pid;
+	p->father = current->pid;
+	p->counter = p->priority;
+	p->signal = 0;
+	p->alarm = 0;
+	p->leader = 0;		/* process leadership doesn't inherit */
+	p->utime = p->stime = 0;
+	p->cutime = p->cstime = 0;
+	p->start_time = jiffies;
+	p->tss.back_link = 0;
+	p->tss.esp0 = PAGE_SIZE + (long)p;
+	p->tss.ss0 = 0x10;
+	p->tss.eip = eip;
+	p->tss.eflags = eflags;
+	p->tss.eax = 0;
+	p->tss.ecx = ecx;
+	p->tss.edx = edx;
+	p->tss.ebx = ebx;
+	p->tss.esp = esp;
+	p->tss.ebp = ebp;
+	p->tss.esi = esi;
+	p->tss.edi = edi;
+	p->tss.es = es & 0xffff;
+	p->tss.cs = cs & 0xffff;
+	p->tss.ss = ss & 0xffff;
+	p->tss.ds = ds & 0xffff;
+	p->tss.fs = fs & 0xffff;
+	p->tss.gs = gs & 0xffff;
+	p->tss.ldt = _LDT(nr);
+	p->tss.trace_bitmap = 0x80000000;
+	if (last_task_used_math == current)
+		__asm__("clts ; fnsave %0"::"m" (p->tss.i387));
+	if (copy_mem(nr, p)) {
+		task[nr] = NULL;
+		free_page((long)p);
+		return -EAGAIN;
+	}
+	for (i = 0; i < NR_OPEN; i++)
+		if (f = p->filp[i])
+			f->f_count++;
+	if (current->pwd)
+		current->pwd->i_count++;
+	if (current->root)
+		current->root->i_count++;
+	if (current->executable)
+		current->executable->i_count++;
+	set_tss_desc(gdt + (nr << 1) + FIRST_TSS_ENTRY, &(p->tss));
+	set_ldt_desc(gdt + (nr << 1) + FIRST_LDT_ENTRY, &(p->ldt));
+	p->state = TASK_RUNNING;	/* do this last, just in case */
+	return last_pid;
+}
+
+int find_empty_process(void)
+{
+	int i;
+
+repeat:
+	if ((++last_pid) < 0) last_pid = 1;
+	for (i = 0; i < NR_TASKS; i++)
+		if (task[i] && task[i]->pid == last_pid) goto repeat;
+	for (i = 1; i < NR_TASKS; i++)
+		if (!task[i])
+			return i;
+	return -EAGAIN;
+}
+
+int sys_pthread_attr_init(pthread_attr_t* attr)        /* ϵͳ����pthread_attr_initʵ�ֺ��� */
+{
+	if (!attr)
+	{
+		printk("Error:init pthread failed!\n");
+		sys_exit(0);
+	}
+	/* �����߳�ջ����ʼ��ַ�ʹ�С */
+	attr->state = 0;
+	attr->stackaddr = current->brk;
+	attr->stacksize = PAGE_SIZE;
+
+	return 0;
+}
+
+int thread_create(int nr, long ebp, long edi, long esi, long gs, long none,
+	long ebx, long ecx, long edx,
+	long fs, long es, long ds,
+	long eip, long cs, long eflags, long esp, long ss)
+{
+	struct task_struct* p;
+	int i;
+	struct file* f;
+	/*******************************************/
+	long func_addr = ecx;       /* ecx�д洢�����̴߳������е���ʼ��ַ��edx�д洢���Ǵ��ݸ��̵߳IJ��� */
+	long func_arg = edx;
+	/*******************************************/
+	p = (struct task_struct*)get_free_page();   /*����һҳ����TCB*/
+	if (!p)
+		return -EAGAIN;
+	task[nr] = p;
+	*p = *current;	/* NOTE! this doesn't copy the supervisor stack */
+	/*******************************************/
+	current->brk = current->brk + PAGE_SIZE;  /*����ͬһ�����ڵ��̹߳������Ե�ַ�ռ䣬������Ҫ����TCB�ĵ�ַ�Լ���ջ��ʼ��ַ*/
+	p->start_stack = current->brk;
+	/*******************************************/
+	p->state = TASK_UNINTERRUPTIBLE;
+	p->pid = last_pid;
+	p->father = current->pid;
+	p->counter = p->priority;
+	p->signal = 0;
+	p->alarm = 0;
+	p->leader = 0;		/* process leadership doesn't inherit */
+	p->utime = p->stime = 0;
+	p->cutime = p->cstime = 0;
+	p->start_time = jiffies;
+
+	p->tss.back_link = 0;
+	p->tss.esp0 = PAGE_SIZE + (long)p;
+	p->tss.ss0 = 0x10;
+	/*********************************************/
+	p->tss.eip = func_addr;   /* ecx�д洢�����̴߳������п�ʼִ�еĵ�ַ */
+	/*********************************************/
+	p->tss.eflags = eflags;
+	p->tss.eax = 0;
+	p->tss.ecx = ecx;
+	p->tss.edx = edx;
+	p->tss.ebx = ebx;
+	/*********************************************/
+	p->tss.esp = current->brk;   /* ջ��ָ��Ӧ�ȳ�ʼ��ΪΪ�̶߳�ջ����ʼ��ַ */
+	/*********************************************/
+	p->tss.ebp = ebp;
+	p->tss.esi = esi;
+	p->tss.edi = edi;
+	p->tss.es = es & 0xffff;
+	p->tss.cs = cs & 0xffff;
+	p->tss.ss = ss & 0xffff;
+	p->tss.ds = ds & 0xffff;
+	p->tss.fs = fs & 0xffff;
+	p->tss.gs = gs & 0xffff;
+	/*********************************************/
+	p->tss.ldt = current->tss.ldt;   /* �����߳���Ҫ�����߳�ldt��ַ��Ϊ�����̵�ldt��ַ */
+	/*********************************************/
+	p->tss.trace_bitmap = 0x80000000;
+
+	if (last_task_used_math == current)
+		__asm__("clts ; fnsave %0"::"m" (p->tss.i387));
+	if (copy_mem(nr, p)) {
+		task[nr] = NULL;
+		free_page((long)p);
+		return -EAGAIN;
+	}
+	/*********************************************/
+	put_fs_long(func_arg, p->tss.esp);    /* ��edx�д�ŵIJ������浽���̵߳Ķ�ջ���� */
+	p->tss.esp -= 4;                      /* �����˶�ջָ����������ƶ��ĸ��ֽڣ��Դ�ŷ��ص�ַ */
+	/*********************************************/
+
+	for (i = 0; i < NR_OPEN; i++)
+		if ((f = p->filp[i]))
+			f->f_count++;
+	if (current->pwd)
+		current->pwd->i_count++;
+	if (current->root)
+		current->root->i_count++;
+	if (current->executable)
+		current->executable->i_count++;
+
+	set_tss_desc(gdt + (nr << 1) + FIRST_TSS_ENTRY, &(p->tss));
+	set_ldt_desc(gdt + (nr << 1) + FIRST_LDT_ENTRY, &(p->ldt));
+	p->state = TASK_RUNNING;
+
+	return p->pid;
+}