diff --git a/Makefile b/Makefile
index fc059f6..641c3ce 100644
--- a/Makefile
+++ b/Makefile
@@ -53,13 +53,16 @@ ld := $(prefix)ld
 objdump := $(prefix)objdump
 cc := $(prefix)gcc
 
-.PHONY: all clean run iso kernel build debug_asm
+.PHONY: all clean run iso kernel build debug_asm doc
 
 all: $(kernel)
 
 clean:
 	@rm -r build target
 
+doc:
+	@cargo rustdoc -- --document-private-items
+
 run: $(iso)
 	@qemu-system-$(arch) $(qemu_opts) || [ $$? -eq 11 ] # run qemu and assert it exit 11
 
diff --git a/src/arch/x86_64/idt.rs b/src/arch/x86_64/idt.rs
index 2014323..c7e5230 100644
--- a/src/arch/x86_64/idt.rs
+++ b/src/arch/x86_64/idt.rs
@@ -7,7 +7,7 @@ pub fn init() {
 
 lazy_static! {
     static ref IDT: Idt = {
-        use arch::interrupt::{handler::*, consts::*};
+        use arch::interrupt::consts::*;
 		use arch::gdt::DOUBLE_FAULT_IST_INDEX;
         use x86_64::PrivilegeLevel;
         use core::mem::transmute;
@@ -19,7 +19,7 @@ lazy_static! {
         // * 某些保留中断号不允许设置，会触发panic
         // 于是下面用了一些trick绕过了它们
 
-        let ring3 = [T_SWITCH_TOK, T_SYSCALL, 0x80];
+        let ring3 = [T_SWITCH_TOK, T_SYSCALL, T_SYSCALL32];
 
         let mut idt = Idt::new();
         let entries = unsafe{ &mut *(&mut idt as *mut _ as *mut [IdtEntry<HandlerFunc>; 256]) };
diff --git a/src/arch/x86_64/interrupt/consts.rs b/src/arch/x86_64/interrupt/consts.rs
index a43869f..bb087a0 100644
--- a/src/arch/x86_64/interrupt/consts.rs
+++ b/src/arch/x86_64/interrupt/consts.rs
@@ -27,6 +27,8 @@ pub const IRQ_IDE      : u8 = 14;
 pub const IRQ_ERROR    : u8 = 19;
 pub const IRQ_SPURIOUS : u8 = 31;
 pub const T_SYSCALL: u8 = 0x40;
-// SYSCALL, ONLY FOR THIS PROJ
+// xv6 x86_64 syscall
+pub const T_SYSCALL32: u8 = 0x80;
+// ucore syscall
 pub const T_SWITCH_TOU : u8 = 120;      // user/kernel switch
 pub const T_SWITCH_TOK : u8 = 121;      // user/kernel switch
\ No newline at end of file
diff --git a/src/arch/x86_64/interrupt/handler.rs b/src/arch/x86_64/interrupt/handler.rs
index cd83f8e..ee9ca0f 100644
--- a/src/arch/x86_64/interrupt/handler.rs
+++ b/src/arch/x86_64/interrupt/handler.rs
@@ -1,3 +1,67 @@
+//! 中断服务例程
+//!
+//! # 中断处理总流程
+//!
+//! * 中断发生时，CPU首先完成以下工作：
+//!     * 设置rsp的值（Ring3->0 或 DoubleFault，在TSS中设置）
+//!     * 向栈中push一些值（Ring0时3项，Ring3时5项，某些中断还有错误码）
+//!     * 跳转到`vector{i}`符号（位于`vector.asm`）
+//! * 进入中断服务例程后，完成以下工作：
+//!     * `vector{i}`向栈中push空错误码（如CPU没有做）和中断号
+//!     * 跳转到`__alltraps`（位于`trap.asm`）
+//!     * `__alltraps`向栈中push全部寄存器的值
+//!     * 调用`rust_trap`，并把此时的rsp传过来，也就是`TrapFrame`的指针
+//! * `rust_trap`完成以下工作：
+//!     * 根据tf中的中断号，再次分发到具体的中断处理函数。
+//!       一些函数可能会修改rsp的值以完成进程切换。
+//!     * 在离开前，检查新的tf中的cs段，如果是用户态，向TSS中设置下一次中断时重置rsp的值，使其指向该用户线程的内核栈
+//!     * 返回新的rsp的值
+//! * `__alltraps`完成以下工作：
+//!     * 重置rsp
+//!     * 从栈中pop全部寄存器的值，pop中断号和错误码
+//!     * 执行iret，CPU从栈中pop一些值（若其中的CS是Ring0，3项，否则5项），重置rip和rsp（Ring3时）
+
+use super::TrapFrame;
+
+#[no_mangle]
+pub extern fn rust_trap(tf: &mut TrapFrame) -> usize {
+    let mut rsp = tf as *const _ as usize;
+
+    // Dispatch
+    match tf.trap_num as u8 {
+        T_BRKPT => breakpoint(),
+        T_DBLFLT => double_fault(),
+        T_PGFLT => page_fault(tf),
+        T_GPFLT => general_protection_fault(),
+        T_IRQ0...64 => {
+            let irq = tf.trap_num as u8 - T_IRQ0;
+            match irq {
+                IRQ_TIMER => timer(tf, &mut rsp),
+                IRQ_KBD => keyboard(),
+                IRQ_COM1 => com1(),
+                IRQ_COM2 => com2(),
+                _ => panic!("Invalid IRQ number."),
+            }
+            #[cfg(feature = "use_apic")]
+            use arch::driver::apic::ack;
+            #[cfg(not(feature = "use_apic"))]
+            use arch::driver::pic::ack;
+            ack(irq);
+        }
+        T_SWITCH_TOK => to_kernel(tf),
+        T_SWITCH_TOU => to_user(tf),
+        T_SYSCALL => syscall(tf, &mut rsp),
+        0x80 => syscall32(tf, &mut rsp),
+        _ => panic!("Unhandled interrupt {:x}", tf.trap_num),
+    }
+
+    // Set return rsp if to user
+    let tf = unsafe { &*(rsp as *const TrapFrame) };
+    set_return_rsp(tf);
+
+    rsp
+}
+
 fn breakpoint() {
     error!("\nEXCEPTION: Breakpoint");
 }
@@ -30,11 +94,6 @@ fn invalid_opcode() {
     loop {}
 }
 
-#[cfg(feature = "use_apic")]
-use arch::driver::apic::ack;
-#[cfg(not(feature = "use_apic"))]
-use arch::driver::pic::ack;
-
 use super::consts::*;
 
 fn keyboard() {
@@ -90,41 +149,6 @@ fn syscall32(tf: &mut TrapFrame, rsp: &mut usize) {
     tf.rax = ret as usize;
 }
 
-#[no_mangle]
-pub extern fn rust_trap(tf: &mut TrapFrame) -> usize {
-    let mut rsp = tf as *const _ as usize;
-
-    // Dispatch
-    match tf.trap_num as u8 {
-        T_BRKPT => breakpoint(),
-        T_DBLFLT => double_fault(),
-        T_PGFLT => page_fault(tf),
-        T_GPFLT => general_protection_fault(),
-        T_IRQ0...64 => {
-            let irq = tf.trap_num as u8 - T_IRQ0;
-            match irq {
-                IRQ_TIMER => timer(tf, &mut rsp),
-                IRQ_KBD => keyboard(),
-                IRQ_COM1 => com1(),
-                IRQ_COM2 => com2(),
-                _ => panic!("Invalid IRQ number."),
-            }
-            ack(irq);
-        }
-        T_SWITCH_TOK => to_kernel(tf),
-        T_SWITCH_TOU => to_user(tf),
-        T_SYSCALL => syscall(tf, &mut rsp),
-        0x80 => syscall32(tf, &mut rsp),
-        _ => panic!("Unhandled interrupt {:x}", tf.trap_num),
-    }
-
-    // Set return rsp if to user
-    let tf = unsafe { &*(rsp as *const TrapFrame) };
-    set_return_rsp(tf);
-
-    rsp
-}
-
 fn set_return_rsp(tf: &TrapFrame) {
     use arch::gdt::Cpu;
     use core::mem::size_of;
@@ -132,33 +156,3 @@ fn set_return_rsp(tf: &TrapFrame) {
         Cpu::current().set_ring0_rsp(tf as *const _ as usize + size_of::<TrapFrame>());
     }
 }
-
-#[derive(Debug, Clone, Default)]
-pub struct TrapFrame {
-    pub r15: usize,
-    pub r14: usize,
-    pub r13: usize,
-    pub r12: usize,
-    pub rbp: usize,
-    pub rbx: usize,
-
-    pub r11: usize,
-    pub r10: usize,
-    pub r9: usize,
-    pub r8: usize,
-    pub rsi: usize,
-    pub rdi: usize,
-    pub rdx: usize,
-    pub rcx: usize,
-    pub rax: usize,
-
-    pub trap_num: usize,
-    pub error_code: usize,
-
-    pub rip: usize,
-    pub cs: usize,
-    pub rflags: usize,
-
-    pub rsp: usize,
-    pub ss: usize,
-}
\ No newline at end of file
diff --git a/src/arch/x86_64/interrupt/mod.rs b/src/arch/x86_64/interrupt/mod.rs
index 4a74fd7..2aa9f87 100644
--- a/src/arch/x86_64/interrupt/mod.rs
+++ b/src/arch/x86_64/interrupt/mod.rs
@@ -1,33 +1,12 @@
 use x86_64;
 use arch::driver::{apic::IOAPIC, pic};
 
-pub mod handler;
 pub mod consts;
+mod handler;
+mod trapframe;
 
-pub use self::handler::TrapFrame;
-
-impl TrapFrame {
-    pub fn new_kernel_thread(entry: extern fn(), rsp: usize) -> Self {
-        use arch::gdt;
-        let mut tf = TrapFrame::default();
-        tf.cs = gdt::KCODE_SELECTOR.0 as usize;
-        tf.rip = entry as usize;
-        tf.ss = gdt::KDATA_SELECTOR.0 as usize;
-        tf.rsp = rsp;
-        tf.rflags = 0x282;
-        tf
-    }
-    pub fn new_user_thread(entry_addr: usize, rsp: usize, is32: bool) -> Self {
-        use arch::gdt;
-        let mut tf = TrapFrame::default();
-        tf.cs = if is32 { gdt::UCODE32_SELECTOR.0 } else { gdt::UCODE_SELECTOR.0 } as usize;
-        tf.rip = entry_addr;
-        tf.ss = if is32 { gdt::UDATA32_SELECTOR.0 } else { gdt::UDATA_SELECTOR.0 } as usize;
-        tf.rsp = rsp;
-        tf.rflags = 0x282;
-        tf
-    }
-}
+pub use self::trapframe::TrapFrame;
+pub use self::handler::rust_trap;
 
 #[inline(always)]
 pub unsafe fn enable() {
diff --git a/src/arch/x86_64/interrupt/trapframe.rs b/src/arch/x86_64/interrupt/trapframe.rs
new file mode 100644
index 0000000..2c5eb76
--- /dev/null
+++ b/src/arch/x86_64/interrupt/trapframe.rs
@@ -0,0 +1,57 @@
+#[derive(Debug, Clone, Default)]
+pub struct TrapFrame {
+    // Pushed by __alltraps at 'trap.asm'
+    pub r15: usize,
+    pub r14: usize,
+    pub r13: usize,
+    pub r12: usize,
+    pub rbp: usize,
+    pub rbx: usize,
+
+    pub r11: usize,
+    pub r10: usize,
+    pub r9: usize,
+    pub r8: usize,
+    pub rsi: usize,
+    pub rdi: usize,
+    pub rdx: usize,
+    pub rcx: usize,
+    pub rax: usize,
+
+    // Pushed by vector{i} at 'vector.asm'
+    pub trap_num: usize,
+    pub error_code: usize,
+
+    // Pushed by CPU
+    pub rip: usize,
+    pub cs: usize,
+    pub rflags: usize,
+
+    // Pushed by CPU when Ring3->0
+    pub rsp: usize,
+    pub ss: usize,
+}
+
+/// 用于在内核栈中构造新线程的中断帧
+impl TrapFrame {
+    pub fn new_kernel_thread(entry: extern fn(), rsp: usize) -> Self {
+        use arch::gdt;
+        let mut tf = TrapFrame::default();
+        tf.cs = gdt::KCODE_SELECTOR.0 as usize;
+        tf.rip = entry as usize;
+        tf.ss = gdt::KDATA_SELECTOR.0 as usize;
+        tf.rsp = rsp;
+        tf.rflags = 0x282;
+        tf
+    }
+    pub fn new_user_thread(entry_addr: usize, rsp: usize, is32: bool) -> Self {
+        use arch::gdt;
+        let mut tf = TrapFrame::default();
+        tf.cs = if is32 { gdt::UCODE32_SELECTOR.0 } else { gdt::UCODE_SELECTOR.0 } as usize;
+        tf.rip = entry_addr;
+        tf.ss = if is32 { gdt::UDATA32_SELECTOR.0 } else { gdt::UDATA_SELECTOR.0 } as usize;
+        tf.rsp = rsp;
+        tf.rflags = 0x282;
+        tf
+    }
+}
\ No newline at end of file
diff --git a/src/lib.rs b/src/lib.rs
index b190b9f..d14444c 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -127,7 +127,7 @@ pub extern "C" fn other_main() -> ! {
     loop {}
 }
 
-pub use arch::interrupt::handler::rust_trap;
+pub use arch::interrupt::rust_trap;
 
 use linked_list_allocator::LockedHeap;