diff --git a/makefile b/makefile
index e3b74c2..2b0b441 100644
--- a/makefile
+++ b/makefile
@@ -22,24 +22,20 @@ $(ISO_DIR):
 	@mkdir -p $(ISO_BOOT_DIR)
 	@mkdir -p $(ISO_GRUB_DIR)
 
-# 編譯 Rust 代碼
 rust-kernel:
 	@echo "Building Rust kernel..."
 	@cargo build $(CARGO_FLAGS)
 
-# 編譯組合語言文件（如果還需要）
 $(OBJECT_DIR)/%.S.o: %.S
 	@mkdir -p $(@D)
 	@echo "Compiling: $< -> $@"
 	@$(CC) $(INCLUDES) -c $< -o $@
 
-# 編譯需要的 C 文件（如果還有）
 $(OBJECT_DIR)/%.c.o: %.c 
 	@mkdir -p $(@D)
 	@echo "Compiling: $< -> $@"
 	@$(CC) $(INCLUDES) -c $< -o $@ $(CFLAGS)
 
-# 連結
 $(BIN_DIR)/$(OS_BIN): $(OBJECT_DIR) $(BIN_DIR) rust-kernel $(SRC)
 	@echo "Linking..."
 	@cp target/$(RUST_TARGET)/$(BUILD_MODE)/libcure.a $(OBJECT_DIR)/
diff --git a/src/arch/x86/boot.S b/src/arch/x86/boot.S
index e8b50fb..f7203fc 100644
--- a/src/arch/x86/boot.S
+++ b/src/arch/x86/boot.S
@@ -18,6 +18,8 @@
 .section .text 
     .global start_
     start_:
+        cli
+        
         movl $stack_top, %esp
         /*
             TODO: kernel init
@@ -27,10 +29,31 @@
         */
         call _kernel_init
 
+        /* install gdt */
+        subl $0x6, %esp
+        movl $_GDT, 2(%esp)
+        movw _GDT_LIMIT, %ax
+        movw %ax, (%esp)
+        lgdt (%esp)
+        addl $0x6, %esp
+
+        /* processing register (CS, ES, SS, DS, FS, GS) */
+        movw $0x10, %cx /* 0x10 in binary representation is 0001 0000. If you right-shift this number by 3 bits, you will get 0000 0010, so the index is 2. */
+        movw %cx, %es
+        movw %cx, %ds
+        movw %cx, %fs
+        movw %cx, %gs
+        movw %cx, %ss
+
+        /* Change CS:IP */
+        pushw $0x08 /* 0x08 in binary representation is 0000 1000. If you right-shift this number by 3 bits, you will get 0000 0001, so the index is 1. */
+        pushl $_after_gdt
+        retf
+
+    _after_gdt: 
         pushl %ebx
         call _kernel_main
-
-        cli
+        
     j_:
         hlt
         jmp j_
\ No newline at end of file
diff --git a/src/hal/cpu.rs b/src/hal/cpu.rs
index 95b0914..1aa15fb 100644
--- a/src/hal/cpu.rs
+++ b/src/hal/cpu.rs
@@ -36,7 +36,7 @@ pub struct SgReg {
 pub fn cpu_r_cr0() -> Reg32 {
     let val: Reg32;
     unsafe {
-        asm!("mov %cr0, {}", out(reg) val);
+        asm!("mov %cr0, {0}", out(reg) val);
     }
     val
 }
@@ -46,7 +46,7 @@ pub fn cpu_r_cr0() -> Reg32 {
 pub fn cpu_r_cr2() -> Reg32 {
     let val: Reg32;
     unsafe {
-        asm!("mov %cr2, {}", out(reg) val);
+        asm!("mov %cr2, {0}", out(reg) val);
     }
     val
 }
@@ -56,7 +56,7 @@ pub fn cpu_r_cr2() -> Reg32 {
 pub fn cpu_r_cr3() -> Reg32 {
     let val: Reg32;
     unsafe {
-        asm!("mov %cr3, {}", out(reg) val);
+        asm!("mov %cr3, {0}", out(reg) val);
     }
     val
 }
@@ -65,7 +65,7 @@ pub fn cpu_r_cr3() -> Reg32 {
 #[inline]
 pub fn cpu_w_cr0(val: Reg32) {
     unsafe {
-        asm!("mov {}, %cr0", in(reg) val);
+        asm!("mov {0}, %cr0", in(reg) val);
     }
 }
 
@@ -73,7 +73,7 @@ pub fn cpu_w_cr0(val: Reg32) {
 #[inline]
 pub fn cpu_w_cr2(val: Reg32) {
     unsafe {
-        asm!("mov {}, %cr2", in(reg) val);
+        asm!("mov {0}, %cr2", in(reg) val);
     }
 }
 
@@ -81,7 +81,7 @@ pub fn cpu_w_cr2(val: Reg32) {
 #[inline]
 pub fn cpu_w_cr3(val: Reg32) {
     unsafe {
-        asm!("mov {}, %cr3", in(reg) val);
+        asm!("mov {0}, %cr3", in(reg) val);
     }
 }
 
@@ -112,12 +112,15 @@ pub fn cpu_get_model(model_out: &mut [u8]) {
     out[1] = edx;
     out[2] = ecx;
     
+    let _max_function_id: u32 = eax;
+
     // 確保以 null 結尾
     if model_out.len() > 12 {
         model_out[12] = 0;
     }
 }
 
+#[allow(dead_code)]
 const BRAND_LEAF: u32 = 0x80000000;
 
 /// 檢查是否支持品牌字串
@@ -136,7 +139,8 @@ pub fn cpu_brand_string_supported() -> bool {
         );
     }
     
-    eax >= 0x80000004
+    // eax >= 0x80000004
+    eax >= BRAND_LEAF + 4
 }
 
 /// 獲取 CPU 品牌字串
diff --git a/src/hal/mod.rs b/src/hal/mod.rs
index 3085b50..8607e9a 100644
--- a/src/hal/mod.rs
+++ b/src/hal/mod.rs
@@ -1,2 +1,23 @@
 pub mod io;
 pub mod cpu;
+
+pub use io::io_port_wb;
+pub use io::io_port_wl;
+pub use io::io_port_rb;
+pub use io::io_port_rl;
+
+pub use cpu::cpu_r_cr0;
+pub use cpu::cpu_r_cr2;
+pub use cpu::cpu_r_cr3;
+pub use cpu::cpu_w_cr0;
+pub use cpu::cpu_w_cr2;
+pub use cpu::cpu_w_cr3;
+pub use cpu::cpu_get_model;
+pub use cpu::cpu_brand_string_supported;
+pub use cpu::cpu_get_brand;
+pub use cpu::cpu_rdtsc;
+pub use cpu::cpu_pause;
+pub use cpu::cpu_halt;
+pub use cpu::cpu_idle;
+pub use cpu::cpu_enable_interrupts;
+pub use cpu::cpu_disable_interrupts;
\ No newline at end of file
diff --git a/src/kernel/asm/mod.rs b/src/kernel/asm/mod.rs
new file mode 100644
index 0000000..a977cad
--- /dev/null
+++ b/src/kernel/asm/mod.rs
@@ -0,0 +1 @@
+pub mod x86;
\ No newline at end of file
diff --git a/src/kernel/asm/x86/gdt.rs b/src/kernel/asm/x86/gdt.rs
new file mode 100644
index 0000000..dd7d045
--- /dev/null
+++ b/src/kernel/asm/x86/gdt.rs
@@ -0,0 +1,115 @@
+// src/kernel/asm/x86/gdt.rs
+
+use core::mem;
+
+#[allow(dead_code)]
+pub const fn sd_type(x: u64) -> u64             { x << 8 }
+#[allow(dead_code)]
+pub const fn sd_code_data(x: u64) -> u64        { x << 12 }
+#[allow(dead_code)]
+pub const fn sd_dpl(x: u64) -> u64              { x << 13 }
+#[allow(dead_code)]
+pub const fn sd_present(x: u64) -> u64          { x << 15 }
+#[allow(dead_code)]
+pub const fn sd_avl(x: u64) -> u64              { x << 20 }
+#[allow(dead_code)]
+pub const fn sd_64bits(x: u64) -> u64           { x << 21 }
+#[allow(dead_code)]
+pub const fn sd_32bits(x: u64) -> u64           { x << 22 }
+#[allow(dead_code)]
+pub const fn sd_4k_gran(x: u64) -> u64          { x << 23 }
+
+#[allow(dead_code)]
+pub const fn seg_lim_l(x: u64) -> u64           { x & 0x0ffff }
+#[allow(dead_code)]
+pub const fn seg_lim_h(x: u64) -> u64           { x & 0xf0000 }
+#[allow(dead_code)]
+pub const fn seg_base_l(x: u64) -> u64          { (x & 0x0000ffff) << 16 }
+#[allow(dead_code)]
+pub const fn seg_base_m(x: u64) -> u64          { (x & 0x00ff0000) >> 16 }
+#[allow(dead_code)]
+pub const fn seg_base_h(x: u64) -> u64          { x & 0xff000000 }
+
+#[allow(dead_code)]
+pub const SEG_DATA_RD: u64 = 0x00; // Read-Only
+#[allow(dead_code)]
+pub const SEG_DATA_RDA: u64 = 0x01; // Read-Only, accessed
+#[allow(dead_code)]
+pub const SEG_DATA_RDWR: u64 = 0x02; // Read/Write
+#[allow(dead_code)]
+pub const SEG_DATA_RDWRA: u64 = 0x03; // Read/Write, accessed
+#[allow(dead_code)]
+pub const SEG_DATA_RDEXPD: u64 = 0x04; // Read-Only, expand-down
+#[allow(dead_code)]
+pub const SEG_DATA_RDEXPDA: u64 = 0x05; // Read-Only, expand-down, accessed
+#[allow(dead_code)]
+pub const SEG_DATA_RDWREXPD: u64 = 0x06; // Read/Write, expand-down
+#[allow(dead_code)]
+pub const SEG_DATA_RDWREXPDA: u64 = 0x07; // Read/Write, expand-down, accessed
+#[allow(dead_code)]
+pub const SEG_CODE_EX: u64 = 0x08; // Execute-Only
+#[allow(dead_code)]
+pub const SEG_CODE_EXA: u64 = 0x09; // Execute-Only, accessed
+#[allow(dead_code)]
+pub const SEG_CODE_EXRD: u64 = 0x0A; // Execute/Read
+#[allow(dead_code)]
+pub const SEG_CODE_EXRDA: u64 = 0x0B; // Execute/Read, accessed
+#[allow(dead_code)]
+pub const SEG_CODE_EXC: u64 = 0x0C; // Execute-Only, conforming
+#[allow(dead_code)]
+pub const SEG_CODE_EXCA: u64 = 0x0D; // Execute-Only, conforming, accessed
+#[allow(dead_code)]
+pub const SEG_CODE_EXRDC: u64 = 0x0E; // Execute/Read, conforming
+#[allow(dead_code)]
+pub const SEG_CODE_EXRDCA: u64 = 0x0F; // Execute/Read, conforming, accessed
+
+#[allow(dead_code)]
+pub const SEG_R0_CODE: u64 = 
+    sd_type(SEG_CODE_EXRD) | sd_code_data(1) | sd_dpl(0) |
+    sd_present(1) | sd_avl(0) | sd_64bits(0) | sd_32bits(1) |
+    sd_4k_gran(1);
+
+#[allow(dead_code)]
+pub const SEG_R0_DATA: u64 = 
+    sd_type(SEG_DATA_RDWR) | sd_code_data(1) | sd_dpl(0) |
+    sd_present(1) | sd_avl(0) | sd_64bits(0) | sd_32bits(1) |
+    sd_4k_gran(1);
+
+#[allow(dead_code)]
+pub const SEG_R3_CODE: u64 = 
+    sd_type(SEG_CODE_EXRD) | sd_code_data(1) | sd_dpl(3) |
+    sd_present(1) | sd_avl(0) | sd_64bits(0) | sd_32bits(1) |
+    sd_4k_gran(1);
+
+#[allow(dead_code)]
+pub const SEG_R3_DATA: u64 = 
+    sd_type(SEG_DATA_RDWR) | sd_code_data(1) | sd_dpl(3) |
+    sd_present(1) | sd_avl(0) | sd_64bits(0) | sd_32bits(1) |
+    sd_4k_gran(1);
+
+pub const GDT_ENTRY: usize = 5;
+
+#[no_mangle]
+pub static mut _GDT: [u64; GDT_ENTRY] = [0; GDT_ENTRY];
+
+#[no_mangle]
+pub static mut _GDT_LIMIT: u16 = (mem::size_of::<[u64; GDT_ENTRY]>() - 1) as u16;
+
+#[no_mangle]
+pub fn _set_gdt_entry(index: usize, base: u64, limit: u64, flags: u64) {
+    unsafe {
+        _GDT[index] = seg_base_h(base) | flags | seg_lim_h(limit) | seg_base_h(base);
+        _GDT[index] <<= 32;
+        _GDT[index] |= seg_base_l(base) | seg_lim_l(limit);
+    }
+    
+}
+
+#[no_mangle]
+pub fn _init_gdt() {
+    _set_gdt_entry(0, 0, 0, 0);
+    _set_gdt_entry(1, 0, 0xfffff, SEG_R0_CODE);
+    _set_gdt_entry(2, 0, 0xfffff, SEG_R0_DATA);
+    _set_gdt_entry(3, 0, 0xfffff, SEG_R3_CODE);
+    _set_gdt_entry(4, 0, 0xfffff, SEG_R3_DATA);
+}
\ No newline at end of file
diff --git a/src/kernel/asm/x86/idt.rs b/src/kernel/asm/x86/idt.rs
new file mode 100644
index 0000000..e69de29
diff --git a/src/kernel/asm/x86/mod.rs b/src/kernel/asm/x86/mod.rs
new file mode 100644
index 0000000..6aed368
--- /dev/null
+++ b/src/kernel/asm/x86/mod.rs
@@ -0,0 +1,2 @@
+pub mod gdt;
+pub mod idt;
\ No newline at end of file
diff --git a/src/kernel/kernel.rs b/src/kernel/kernel.rs
index 9befe22..ddd84fe 100644
--- a/src/kernel/kernel.rs
+++ b/src/kernel/kernel.rs
@@ -3,6 +3,7 @@ use core::arch::asm;
 use crate::kernel::tty::tty;
 use crate::hal::cpu;
 use crate::{print, println};
+use crate::kernel::asm::x86::gdt;
 
 // boot.S 調用的入口點
 #[no_mangle]
@@ -12,6 +13,8 @@ pub extern "C" fn _kernel_init() {
     // TODO: 啟用分頁
     tty::tty_init(tty::VGA_BUFFER_PADDR);
     tty::tty_set_theme(tty::VGA_COLOR_WHITE, tty::VGA_COLOR_BLACK);
+
+    gdt::_init_gdt();
 }
 
 #[no_mangle]
@@ -38,8 +41,15 @@ pub extern "C" fn _kernel_main() {
     println!("10: {}, 16: {:x}", value, value);
 
     unsafe {
-        loop {
-            cpu::cpu_idle();
+        let limit = gdt::_GDT_LIMIT;
+        println!("GDT Limit: {:#x}", limit);
+        for i in 0..gdt::GDT_ENTRY {
+            println!("GDT[{}] = {:#018x}", i, gdt::_GDT[i]);
         }
     }
+
+
+    loop {
+        cpu::cpu_idle();
+    }
 }
\ No newline at end of file
diff --git a/src/kernel/mod.rs b/src/kernel/mod.rs
index 8264245..53c0c05 100644
--- a/src/kernel/mod.rs
+++ b/src/kernel/mod.rs
@@ -1,5 +1,6 @@
 pub mod kernel;
 pub mod tty;
+pub mod asm;
 
 // 重新導出由 boot.S 調用的入口點
 // pub use kernel::{_kernel_init, _kernel_main};
\ No newline at end of file
diff --git a/src/kernel/tty/mod.rs b/src/kernel/tty/mod.rs
index 67b2091..393aac4 100644
--- a/src/kernel/tty/mod.rs
+++ b/src/kernel/tty/mod.rs
@@ -2,7 +2,6 @@
 
 pub mod tty;
 
-// 重新導出 TTY 公共函數
 pub use tty::tty_init;
 pub use tty::tty_set_buffer;
 pub use tty::tty_set_theme;
diff --git a/src/kernel/tty/tty.rs b/src/kernel/tty/tty.rs
index 7e95c9b..3404634 100644
--- a/src/kernel/tty/tty.rs
+++ b/src/kernel/tty/tty.rs
@@ -1,6 +1,7 @@
 // src/kernel/tty/tty.rs
 
 use crate::hal::io::{io_port_wb};
+use core::ptr::NonNull;
 
 /// VGA 屬性類型 (16位)
 pub type VgaAttribute = u16;
@@ -31,7 +32,7 @@ const VGA_DATA_PORT: u16 = 0x03D5;
 
 // 全局 TTY 狀態
 pub struct TTYState {
-    vga_buffer: *mut VgaAttribute,
+    vga_buffer: Option<NonNull<VgaAttribute>>,
     theme_color: VgaAttribute,
     x: usize,
     y: usize,
@@ -40,7 +41,7 @@ pub struct TTYState {
 impl TTYState {
     const fn new() -> Self {
         Self {
-            vga_buffer: VGA_BUFFER_PADDR as *mut VgaAttribute,
+            vga_buffer: None,
             theme_color: (VGA_COLOR_BLACK as VgaAttribute) << 8,
             x: 0,
             y: 0,
@@ -50,6 +51,7 @@ impl TTYState {
 
 static mut TTY_STATE: TTYState = TTYState::new();
 
+#[no_mangle]
 fn update_cursor() {
     unsafe {
         let pos = TTY_STATE.y * TTY_WIDTH + TTY_STATE.x;
@@ -63,21 +65,24 @@ fn update_cursor() {
 
 /// 初始化 TTY
 // vga_buf: *mut u8
+#[no_mangle]
 pub fn tty_init(vga_buf: usize) {
     unsafe {
-        TTY_STATE.vga_buffer = vga_buf as *mut VgaAttribute;
+        TTY_STATE.vga_buffer = NonNull::new(vga_buf as *mut VgaAttribute);
         tty_clear();
     }
 }
 
 /// 設置 VGA 緩衝區
+#[no_mangle]
 pub fn tty_set_buffer(vga_buf: usize) {
     unsafe {
-        TTY_STATE.vga_buffer = vga_buf as *mut VgaAttribute;
+        TTY_STATE.vga_buffer = NonNull::new(vga_buf as *mut VgaAttribute);
     }
 }
 
 /// 設置主題顏色（前景色和背景色）
+#[no_mangle]
 pub fn tty_set_theme(fg: u8, bg: u8) {
     unsafe {
         TTY_STATE.theme_color = ((bg << 4 | fg) as VgaAttribute) << 8;
@@ -92,37 +97,40 @@ pub fn tty_set_theme(fg: u8, bg: u8) {
 /// - '\t' 擴展為 4 個空格
 /// - '\n' 換行並將游標移至行首
 /// - '\r' 將游標移至行首
+#[no_mangle]
 pub fn tty_put_char(chr: char) {
     unsafe {
-        match chr {
-            '\t' => {
-                TTY_STATE.x += 4;
+        if let Some(vga_ptr) = TTY_STATE.vga_buffer {
+            match chr {
+                '\t' => {
+                    TTY_STATE.x += 4;
+                }
+                '\n' => {
+                    TTY_STATE.y += 1;
+                    TTY_STATE.x = 0;
+                }
+                '\r' => {
+                    TTY_STATE.x = 0;
+                }
+                _ => {
+                    let offset = TTY_STATE.x + TTY_STATE.y * TTY_WIDTH;
+                    // VGA 文本模式僅支持 8 位字符
+                    *vga_ptr.as_ptr().add(offset) = TTY_STATE.theme_color | (chr as u8) as VgaAttribute;
+                    TTY_STATE.x += 1;
+                }
             }
-            '\n' => {
+
+            if TTY_STATE.x >= TTY_WIDTH {
+                TTY_STATE.x = 0;
                 TTY_STATE.y += 1;
-                TTY_STATE.x = 0;
             }
-            '\r' => {
-                TTY_STATE.x = 0;
+            
+            if TTY_STATE.y >= TTY_HEIGHT {
+                tty_scroll_up();
             }
-            _ => {
-                let offset = TTY_STATE.x + TTY_STATE.y * TTY_WIDTH;
-                // VGA 文本模式僅支持 8 位字符
-                *TTY_STATE.vga_buffer.add(offset) = TTY_STATE.theme_color | (chr as u8) as VgaAttribute;
-                TTY_STATE.x += 1;
-            }
-        }
 
-        if TTY_STATE.x >= TTY_WIDTH {
-            TTY_STATE.x = 0;
-            TTY_STATE.y += 1;
+            update_cursor();
         }
-        
-        if TTY_STATE.y >= TTY_HEIGHT {
-            tty_scroll_up();
-        }
-
-        update_cursor();
     }
 }
 
@@ -131,6 +139,7 @@ pub fn tty_put_char(chr: char) {
 /// # 注意
 /// - 字符串中的多字節 Unicode 字符會被截斷為低 8 位
 /// - 支持 Rust 字符串切片 (&str)
+#[no_mangle]
 pub fn tty_put_str(s: &str) {
     for chr in s.chars() {
         tty_put_char(chr);
@@ -138,48 +147,64 @@ pub fn tty_put_str(s: &str) {
 }
 
 /// 向上滾動一行
+#[no_mangle]
 pub fn tty_scroll_up() {
     unsafe {
-        let last_line = TTY_WIDTH * (TTY_HEIGHT - 1);
-        
-        // 將所有行向上移動一行
-        core::ptr::copy(
-            TTY_STATE.vga_buffer.add(TTY_WIDTH),
-            TTY_STATE.vga_buffer,
-            last_line
-        );
-        
-        // 清空最後一行
-        for i in 0..TTY_WIDTH {
-            *TTY_STATE.vga_buffer.add(i + last_line) = TTY_STATE.theme_color;
+        if let Some(vga_ptr) = TTY_STATE.vga_buffer {
+            let last_line = TTY_WIDTH * (TTY_HEIGHT - 1);
+            let buffer_ptr = vga_ptr.as_ptr();
+            
+            // 將所有行向上移動一行
+            core::ptr::copy(
+                buffer_ptr.add(TTY_WIDTH),
+                buffer_ptr,
+                last_line
+            );
+            
+            // 清空最後一行
+            for i in 0..TTY_WIDTH {
+                *buffer_ptr.add(i + last_line) = TTY_STATE.theme_color;
+            }
+            
+            TTY_STATE.y = if TTY_STATE.y == 0 { 0 } else { TTY_HEIGHT - 1 };
         }
-        
-        TTY_STATE.y = if TTY_STATE.y == 0 { 0 } else { TTY_HEIGHT - 1 };
     }
 }
 
 /// 清空屏幕
+#[no_mangle]
 pub fn tty_clear() {
     unsafe {
-        for i in 0..(TTY_WIDTH * TTY_HEIGHT) {
-            *TTY_STATE.vga_buffer.add(i) = TTY_STATE.theme_color;
+        if let Some(vga_ptr) = TTY_STATE.vga_buffer {
+            let buffer_ptr = vga_ptr.as_ptr();
+
+            for i in 0..(TTY_WIDTH * TTY_HEIGHT) {
+                *buffer_ptr.add(i) = TTY_STATE.theme_color;
+            }
+
+            TTY_STATE.x = 0;
+            TTY_STATE.y = 0;
+            update_cursor();
         }
-        TTY_STATE.x = 0;
-        TTY_STATE.y = 0;
-        update_cursor();
     }
 }
 
 /// 清空指定行
+#[no_mangle]
 pub fn tty_clear_line(y: usize) {
     unsafe {
-        for i in 0..TTY_WIDTH {
-            *TTY_STATE.vga_buffer.add(i + y * TTY_WIDTH) = TTY_STATE.theme_color;
+        if let Some(vga_ptr) = TTY_STATE.vga_buffer {
+            let buffer_ptr = vga_ptr.as_ptr();
+
+            for i in 0..TTY_WIDTH {
+                *buffer_ptr.add(i + y * TTY_WIDTH) = TTY_STATE.theme_color;
+            }
         }
     }
 }
 
 /// 設置游標位置
+#[no_mangle]
 pub fn tty_set_cpos(x: usize, y: usize) {
     unsafe {
         TTY_STATE.x = x % TTY_WIDTH;
@@ -189,6 +214,7 @@ pub fn tty_set_cpos(x: usize, y: usize) {
 }
 
 /// 獲取游標位置
+#[no_mangle]
 pub fn tty_get_cpos() -> (usize, usize) {
     unsafe {
         (TTY_STATE.x, TTY_STATE.y)
@@ -196,6 +222,7 @@ pub fn tty_get_cpos() -> (usize, usize) {
 }
 
 /// 獲取當前主題顏色
+#[no_mangle]
 pub fn tty_get_theme() -> VgaAttribute {
     unsafe {
         TTY_STATE.theme_color