diff --git a/os/src/sbi.rs b/os/src/sbi.rs
index 326f4d63..2c0aaa51 100644
--- a/os/src/sbi.rs
+++ b/os/src/sbi.rs
@@ -1,15 +1,3 @@
-/// use sbi call to putchar in console (qemu uart handler)
-pub fn console_putchar(c: usize) {
-    #[allow(deprecated)]
-    sbi_rt::legacy::console_putchar(c);
-}
-
-/// use sbi call to getchar from console (qemu uart handler)
-pub fn console_getchar() -> usize {
-    #[allow(deprecated)]
-    sbi_rt::legacy::console_getchar()
-}
-
 /// use sbi call to set timer
 pub fn set_timer(timer: usize) {
     sbi_rt::set_timer(timer as _);
diff --git a/os/src/task/mod.rs b/os/src/task/mod.rs
index de611f35..a8b9b7b4 100644
--- a/os/src/task/mod.rs
+++ b/os/src/task/mod.rs
@@ -57,7 +57,6 @@ pub fn block_current_and_run_next() {
     let task_cx_ptr = block_current_task();
     schedule(task_cx_ptr);
 }
-use crate::board::QEMUExit;
 
 /// Exit the current 'Running' task and run the next task in task list.
 pub fn exit_current_and_run_next(exit_code: i32) {
diff --git a/user/src/bin/gui_rect.rs b/user/src/bin/gui_rect.rs
index a459dbc3..b7af3ee7 100644
--- a/user/src/bin/gui_rect.rs
+++ b/user/src/bin/gui_rect.rs
@@ -58,8 +58,8 @@ impl DrawingBoard {
 pub fn main() -> i32 {
     let mut board = DrawingBoard::new();
     let _ = board.disp.clear(Rgb888::BLACK).unwrap();
-    for i in 0..5 {
-        board.latest_pos.x += (RECT_SIZE as i32 + 20);
+    for _ in 0..5 {
+        board.latest_pos.x += RECT_SIZE as i32 + 20;
         //board.latest_pos.y += i;
         board.paint();
     }