diff --git a/kernel/src/arch/mipsel/board/thinpad/consts.rs b/kernel/src/arch/mipsel/board/thinpad/consts.rs
index b59309a..db1971f 100644
--- a/kernel/src/arch/mipsel/board/thinpad/consts.rs
+++ b/kernel/src/arch/mipsel/board/thinpad/consts.rs
@@ -1,3 +1,3 @@
 /// board specific constants
 pub const MEMORY_END: usize = 0x8080_0000;
-pub const KERNEL_HEAP_SIZE: usize = 0x0020_0000;
+pub const KERNEL_HEAP_SIZE: usize = 0x0038_0000;
diff --git a/kernel/src/arch/mipsel/interrupt.rs b/kernel/src/arch/mipsel/interrupt.rs
index 56757c4..60abde3 100644
--- a/kernel/src/arch/mipsel/interrupt.rs
+++ b/kernel/src/arch/mipsel/interrupt.rs
@@ -29,6 +29,9 @@ pub fn init() {
         status.enable_soft_int1();
         // Enable clock interrupt
         status.enable_hard_int5();
+        // Enable serial interrupt
+        #[cfg(feature = "board_thinpad")]
+        status.enable_hard_int0();
 
         cp0::status::write(status);
     }
@@ -209,6 +212,11 @@ fn reserved_inst(tf: &mut TrapFrame) -> bool {
     let sel = (inst >> 6) & 0b111;
     let format = inst & 0b111111;
 
+    if inst == 0x42000020 {
+        // ignore WAIT
+        return true;
+    }
+
     if opcode == 0b011111 && format == 0b111011 {
         // RDHWR
         if rd == 29 && sel == 0 {
diff --git a/kernel/src/shell.rs b/kernel/src/shell.rs
index 000ad63..74b6330 100644
--- a/kernel/src/shell.rs
+++ b/kernel/src/shell.rs
@@ -6,7 +6,7 @@ use crate::process::*;
 use alloc::string::String;
 use alloc::vec::Vec;
 
-#[cfg(not(feature = "run_cmdline"))]
+#[cfg(not(any(feature = "run_cmdline", feature = "board_thinpad")))]
 pub fn run_user_shell() {
     if let Ok(inode) = ROOT_INODE.lookup("busybox") {
         let data = inode.read_as_vec().unwrap();
@@ -21,6 +21,21 @@ pub fn run_user_shell() {
     }
 }
 
+#[cfg(feature = "board_thinpad")]
+pub fn run_user_shell() {
+    if let Ok(inode) = ROOT_INODE.lookup("sh") {
+        let data = inode.read_as_vec().unwrap();
+        processor().manager().add(Thread::new_user(
+            data.as_slice(),
+            "sh",
+            vec!["sh".into()],
+            Vec::new(),
+        ));
+    } else {
+        processor().manager().add(Thread::new_kernel(shell, 0));
+    }
+}
+
 #[cfg(feature = "run_cmdline")]
 pub fn run_user_shell() {
     let cmdline = CMDLINE.read();