diff --git a/kernel/src/arch/mipsel/board/malta/consts.rs b/kernel/src/arch/mipsel/board/malta/consts.rs
new file mode 100644
index 0000000..5f1f8f5
--- /dev/null
+++ b/kernel/src/arch/mipsel/board/malta/consts.rs
@@ -0,0 +1,3 @@
+/// board specific constants for malta
+pub const MEMORY_END: usize = 0x8800_0000;
+pub const KERNEL_HEAP_SIZE: usize = 0x00a0_0000;
diff --git a/kernel/src/arch/mipsel/board/malta/mod.rs b/kernel/src/arch/mipsel/board/malta/mod.rs
index d9b9d0b..05b27b7 100644
--- a/kernel/src/arch/mipsel/board/malta/mod.rs
+++ b/kernel/src/arch/mipsel/board/malta/mod.rs
@@ -6,6 +6,7 @@ pub mod serial;
 pub mod fb;
 #[path = "../../../../drivers/console/mod.rs"]
 pub mod console;
+pub mod consts;
 
 /// Initialize serial port first
 pub fn init_serial_early() {
diff --git a/kernel/src/arch/mipsel/board/malta/serial.rs b/kernel/src/arch/mipsel/board/malta/serial.rs
index 2618e0d..b624729 100644
--- a/kernel/src/arch/mipsel/board/malta/serial.rs
+++ b/kernel/src/arch/mipsel/board/malta/serial.rs
@@ -83,7 +83,7 @@ impl Write for SerialPort {
 
 fn write<T>(addr: usize, content: T) {
     let cell = (addr) as *mut T;
-    unsafe { write_volatile(cell, content) }
+    unsafe { write_volatile(cell, content); }
 }
 
 fn read<T>(addr: usize) -> T {
diff --git a/kernel/src/arch/mipsel/board/thinpad/consts.rs b/kernel/src/arch/mipsel/board/thinpad/consts.rs
new file mode 100644
index 0000000..9a10cde
--- /dev/null
+++ b/kernel/src/arch/mipsel/board/thinpad/consts.rs
@@ -0,0 +1,3 @@
+/// board specific constants for thinpad
+pub const MEMORY_END: usize = 0x8080_0000;
+pub const KERNEL_HEAP_SIZE: usize = 0x0020_0000;
diff --git a/kernel/src/arch/mipsel/board/thinpad/mod.rs b/kernel/src/arch/mipsel/board/thinpad/mod.rs
index a290559..358197f 100644
--- a/kernel/src/arch/mipsel/board/thinpad/mod.rs
+++ b/kernel/src/arch/mipsel/board/thinpad/mod.rs
@@ -1,10 +1,14 @@
 use once::*;
+use alloc::string::String;
 
 pub mod serial;
 #[path = "../../../../drivers/gpu/fb.rs"]
 pub mod fb;
 #[path = "../../../../drivers/console/mod.rs"]
 pub mod console;
+pub mod consts;
+
+use fb::FramebufferInfo;
 
 /// Initialize serial port first
 pub fn init_serial_early() {
@@ -31,6 +35,6 @@ pub fn probe_fb_info(width: u32, height: u32, depth: u32) -> Result<(Framebuffer
         pitch: 800,
         bus_addr: 0xa2000000,
         screen_size: 800 * 600,
-    }
+    };
     Ok((fb_info, 0xa2000000))
 }
\ No newline at end of file
diff --git a/kernel/src/arch/mipsel/board/thinpad/serial.rs b/kernel/src/arch/mipsel/board/thinpad/serial.rs
index 3c59a0d..95c693d 100644
--- a/kernel/src/arch/mipsel/board/thinpad/serial.rs
+++ b/kernel/src/arch/mipsel/board/thinpad/serial.rs
@@ -4,7 +4,7 @@ use core::fmt::{Write, Result, Arguments};
 use core::ptr::{read_volatile, write_volatile};
 use spin::Mutex;
 
-struct SerialPort {
+pub struct SerialPort {
     base: usize
 }
 
@@ -27,7 +27,7 @@ impl SerialPort {
     }
 
     /// non-blocking version of putchar()
-    fn putchar(&mut self, c: u8) {
+    pub fn putchar(&mut self, c: u8) {
         write(self.base + UART_DATA, c);
     }
 
@@ -76,12 +76,12 @@ impl Write for SerialPort {
 
 fn write<T>(addr: usize, content: T) {
     let cell = (addr) as *mut T;
-    write_volatile(cell, content);
+    unsafe { write_volatile(cell, content); }
 }
 
 fn read<T>(addr: usize) -> T {
     let cell = (addr) as *const T;
-    read_volatile(cell);
+    unsafe { read_volatile(cell) }
 }
 
 
diff --git a/kernel/src/arch/mipsel/boot/linker.ld b/kernel/src/arch/mipsel/boot/linker.ld
index 8570468..7911721 100644
--- a/kernel/src/arch/mipsel/boot/linker.ld
+++ b/kernel/src/arch/mipsel/boot/linker.ld
@@ -4,7 +4,7 @@
 OUTPUT_ARCH(riscv)
 ENTRY(_start)
 
-BASE_ADDRESS = 0x80100000;
+BASE_ADDRESS = 0x80000000;
 
 SECTIONS
 {
diff --git a/kernel/src/arch/mipsel/consts.rs b/kernel/src/arch/mipsel/consts.rs
index ab7bf18..1bc6aa5 100644
--- a/kernel/src/arch/mipsel/consts.rs
+++ b/kernel/src/arch/mipsel/consts.rs
@@ -1,11 +1,11 @@
 /// Platform specific constants
+/// 
 
-pub const KERNEL_OFFSET: usize = 0x80100000;
+pub use super::board::consts::*;
 
-pub const KERNEL_HEAP_SIZE: usize = 0x00a0_0000;
+pub const KERNEL_OFFSET: usize = 0x80000000;
 
 pub const MEMORY_OFFSET: usize = 0x8000_0000;
-pub const MEMORY_END: usize = 0x8800_0000;
 
 pub const USER_STACK_OFFSET: usize = 0x80000000 - USER_STACK_SIZE;
 pub const USER_STACK_SIZE: usize = 0x10000;