diff --git a/src/bin/ch7b_pipe_large_test.rs b/src/bin/ch7b_pipe_large_test.rs
index 430e459..c7b05e2 100644
--- a/src/bin/ch7b_pipe_large_test.rs
+++ b/src/bin/ch7b_pipe_large_test.rs
@@ -7,7 +7,7 @@ extern crate user_lib;
 extern crate alloc;
 
 use alloc::format;
-use user_lib::{close, fork, get_time, pipe, read, wait, write,getpid};
+use user_lib::{close, fork, pipe, read, wait, write,getpid};
 
 const LENGTH: usize = 3000;
 #[no_mangle]
diff --git a/src/bin/ch8b_race_adder.rs b/src/bin/ch8b_race_adder.rs
index 139e137..538e5a3 100644
--- a/src/bin/ch8b_race_adder.rs
+++ b/src/bin/ch8b_race_adder.rs
@@ -6,6 +6,7 @@ extern crate user_lib;
 extern crate alloc;
 
 use alloc::vec::Vec;
+use core::ptr::addr_of_mut;
 use user_lib::{exit, get_time, thread_create, waittid};
 
 static mut A: usize = 0;
@@ -15,7 +16,7 @@ const THREAD_COUNT: usize = 16;
 unsafe fn f() -> ! {
     let mut t = 2usize;
     for _ in 0..PER_THREAD {
-        let a = &mut A as *mut usize;
+        let a = addr_of_mut!(A) as *mut usize;
         let cur = a.read_volatile();
         for _ in 0..500 {
             t = t * t % 10007;
diff --git a/src/bin/ch8b_race_adder_atomic.rs b/src/bin/ch8b_race_adder_atomic.rs
index c00fe6a..d18fe63 100644
--- a/src/bin/ch8b_race_adder_atomic.rs
+++ b/src/bin/ch8b_race_adder_atomic.rs
@@ -6,6 +6,7 @@ extern crate user_lib;
 extern crate alloc;
 
 use alloc::vec::Vec;
+use core::ptr::addr_of_mut;
 use core::sync::atomic::{AtomicBool, Ordering};
 use user_lib::{exit, get_time, thread_create, waittid, yield_};
 
@@ -23,7 +24,7 @@ unsafe fn f() -> ! {
         {
             yield_();
         }
-        let a = &mut A as *mut usize;
+        let a = addr_of_mut!(A) as *mut usize;
         let cur = a.read_volatile();
         for _ in 0..500 {
             t = t * t % 10007;
diff --git a/src/bin/ch8b_race_adder_loop.rs b/src/bin/ch8b_race_adder_loop.rs
index 11a0324..27415c0 100644
--- a/src/bin/ch8b_race_adder_loop.rs
+++ b/src/bin/ch8b_race_adder_loop.rs
@@ -1,11 +1,12 @@
 #![no_std]
 #![no_main]
 
+extern crate alloc;
 #[macro_use]
 extern crate user_lib;
-extern crate alloc;
 
 use alloc::vec::Vec;
+use core::ptr::addr_of_mut;
 use user_lib::{exit, get_time, thread_create, waittid, yield_};
 
 static mut A: usize = 0;
@@ -21,7 +22,7 @@ unsafe fn f() -> ! {
         }
         OCCUPIED = true;
         // enter critical section
-        let a = &mut A as *mut usize;
+        let a = addr_of_mut!(A) as *mut usize;
         let cur = a.read_volatile();
         for _ in 0..500 {
             t = t * t % 10007;
diff --git a/src/bin/ch8b_race_adder_mutex_spin.rs b/src/bin/ch8b_race_adder_mutex_spin.rs
index d2df338..223d8f1 100644
--- a/src/bin/ch8b_race_adder_mutex_spin.rs
+++ b/src/bin/ch8b_race_adder_mutex_spin.rs
@@ -6,6 +6,7 @@ extern crate user_lib;
 extern crate alloc;
 
 use alloc::vec::Vec;
+use core::ptr::addr_of_mut;
 use user_lib::{exit, get_time, thread_create, waittid};
 use user_lib::{mutex_create, mutex_lock, mutex_unlock};
 
@@ -17,7 +18,7 @@ unsafe fn f() -> ! {
     let mut t = 2usize;
     for _ in 0..PER_THREAD {
         mutex_lock(0);
-        let a = &mut A as *mut usize;
+        let a = addr_of_mut!(A) as *mut usize;
         let cur = a.read_volatile();
         for _ in 0..500 {
             t = t * t % 10007;
diff --git a/src/bin/ch8b_stackful_coroutine.rs b/src/bin/ch8b_stackful_coroutine.rs
index 2341547..c5847d2 100644
--- a/src/bin/ch8b_stackful_coroutine.rs
+++ b/src/bin/ch8b_stackful_coroutine.rs
@@ -33,6 +33,7 @@ enum State {
 }
 
 struct Task {
+    #[allow(dead_code)]
     id: usize,
     stack: Vec<u8>,
     ctx: TaskContext,
@@ -256,7 +257,7 @@ pub fn yield_task() {
 /// see: https://doc.rust-lang.org/nightly/rust-by-example/unsafe/asm.html
 #[naked]
 #[no_mangle]
-unsafe fn switch(old: *mut TaskContext, new: *const TaskContext) {
+unsafe extern "C" fn switch(old: *mut TaskContext, new: *const TaskContext) {
     // a0: _old, a1: _new
     asm!(
         "