begin implementation of IDT

19 files changed, 310 insertions, 43 deletions

diff --git a/arch/x86_64/CMakeLists.txt b/arch/x86_64/CMakeLists.txt
index aad7951..a435ef9 100644
--- a/arch/x86_64/CMakeLists.txt
+++ b/arch/x86_64/CMakeLists.txt
@@ -9,6 +9,9 @@ target_sources("_kernel" PRIVATE
   "src/kernel/main.cpp"
   "src/kernel/cpu/control_register.cpp"
   "src/kernel/cpu/gdtr.cpp"
+  "src/kernel/cpu/idtr.cpp"
+  "src/kernel/cpu/if.cpp"
+  "src/kernel/cpu/jmp.cpp"
   "src/kernel/cpu/msr.cpp"
   "src/kernel/cpu/ss.cpp"
   "src/kernel/cpu/tlb.cpp"
@@ -90,9 +93,13 @@ target_sources("_exception" PRIVATE
 
 target_sources("_context" PRIVATE
   "src/context_switching/descriptor_table/access_byte.cpp"
+  "src/context_switching/descriptor_table/gate_descriptor.cpp"
   "src/context_switching/descriptor_table/gdt_flags.cpp"
   "src/context_switching/descriptor_table/global_descriptor_table.cpp"
   "src/context_switching/descriptor_table/global_descriptor_table_pointer.cpp"
+  "src/context_switching/descriptor_table/initialization.cpp"
+  "src/context_switching/descriptor_table/interrupt_descriptor_table.cpp"
+  "src/context_switching/descriptor_table/interrupt_descriptor_table_pointer.cpp"
   "src/context_switching/descriptor_table/segment_descriptor.cpp"
 )
 
diff --git a/arch/x86_64/include/arch/boot/pointers.hpp b/arch/x86_64/include/arch/boot/pointers.hpp
index fe9c657..2a43f22 100644
--- a/arch/x86_64/include/arch/boot/pointers.hpp
+++ b/arch/x86_64/include/arch/boot/pointers.hpp
@@ -10,6 +10,11 @@ namespace teachos::arch::boot
    */
   extern "C" size_t const multiboot_information_pointer;
 
+  /**
+   * @brief Address pointing to the start of the multiboot information structure.
+   */
+  extern "C" size_t const segment_register_reload_pointer;
+
 }  // namespace teachos::arch::boot
 
 #endif  // TEACHOS_ARCH_X86_64_BOOT_POINTERS_HPP
diff --git a/arch/x86_64/include/arch/context_switching/descriptor_table/gate_descriptor.hpp b/arch/x86_64/include/arch/context_switching/descriptor_table/gate_descriptor.hpp
new file mode 100644
index 0000000..f410219
--- /dev/null
+++ b/arch/x86_64/include/arch/context_switching/descriptor_table/gate_descriptor.hpp
@@ -0,0 +1,15 @@
+#ifndef TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_DESCRIPTOR_TABLE_GATE_DESCRIPTOR_HPP
+#define TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_DESCRIPTOR_TABLE_GATE_DESCRIPTOR_HPP
+
+namespace teachos::arch::context_switching::descriptor_table
+{
+  struct [[gnu::packed]] gate_descriptor
+  {
+    /**
+     * @brief Default Constructor.
+     */
+    gate_descriptor() = default;
+  };
+}  // namespace teachos::arch::context_switching::descriptor_table
+
+#endif  // TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_DESCRIPTOR_TABLE_GATE_DESCRIPTOR_HPP
diff --git a/arch/x86_64/include/arch/context_switching/descriptor_table/initialization.hpp b/arch/x86_64/include/arch/context_switching/descriptor_table/initialization.hpp
new file mode 100644
index 0000000..c587000
--- /dev/null
+++ b/arch/x86_64/include/arch/context_switching/descriptor_table/initialization.hpp
@@ -0,0 +1,23 @@
+#ifndef TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_DESCRIPTOR_TABLE_HPP
+#define TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_DESCRIPTOR_TABLE_HPP
+
+#include "arch/context_switching/descriptor_table/global_descriptor_table.hpp"
+#include "arch/context_switching/descriptor_table/interrupt_descriptor_table.hpp"
+
+namespace teachos::arch::context_switching::descriptor_table
+{
+  /**
+   * @brief TODO
+   *
+   */
+  struct descriptor_tables
+  {
+    global_descriptor_table & gdt;     ///< Reference to the global descriptor table.
+    interrupt_descriptor_table & idt;  ///< Reference to the interrupt descriptor table.
+  };
+
+  auto initialize_descriptor_tables() -> descriptor_tables;
+
+}  // namespace teachos::arch::context_switching::descriptor_table
+
+#endif  // TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_DESCRIPTOR_TABLE_HPP
diff --git a/arch/x86_64/include/arch/context_switching/descriptor_table/interrupt_descriptor_table.hpp b/arch/x86_64/include/arch/context_switching/descriptor_table/interrupt_descriptor_table.hpp
new file mode 100644
index 0000000..c63932d
--- /dev/null
+++ b/arch/x86_64/include/arch/context_switching/descriptor_table/interrupt_descriptor_table.hpp
@@ -0,0 +1,14 @@
+#ifndef TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_DESCRIPTOR_TABLE_INTERRUPT_DESCRIPTOR_TABLE_HPP
+#define TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_DESCRIPTOR_TABLE_INTERRUPT_DESCRIPTOR_TABLE_HPP
+
+namespace teachos::arch::context_switching::descriptor_table
+{
+  struct interrupt_descriptor_table
+  {
+  };
+
+  auto initialize_interrupt_descriptor_table() -> void;
+
+}  // namespace teachos::arch::context_switching::descriptor_table
+
+#endif  // TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_DESCRIPTOR_TABLE_INTERRUPT_DESCRIPTOR_TABLE_HPP
diff --git a/arch/x86_64/include/arch/context_switching/descriptor_table/interrupt_descriptor_table_pointer.hpp b/arch/x86_64/include/arch/context_switching/descriptor_table/interrupt_descriptor_table_pointer.hpp
new file mode 100644
index 0000000..e8935f4
--- /dev/null
+++ b/arch/x86_64/include/arch/context_switching/descriptor_table/interrupt_descriptor_table_pointer.hpp
@@ -0,0 +1,42 @@
+#ifndef TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_DESCRIPTOR_TABLE_INTERRUPT_DESCRIPTOR_TABLE_POINTER_HPP
+#define TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_DESCRIPTOR_TABLE_INTERRUPT_DESCRIPTOR_TABLE_POINTER_HPP
+
+#include "arch/context_switching/descriptor_table/gate_descriptor.hpp"
+#include "arch/stl/vector.hpp"
+
+#include <cstdint>
+
+namespace teachos::arch::context_switching::descriptor_table
+{
+  typedef stl::vector<gate_descriptor> interrupt_descriptor_table;
+
+  /**
+   * @brief Represents a pointer to the Interrupt Descriptor Table (IDT).
+   *
+   * This structure is used to store the base address and length of the IDT.
+   */
+  struct [[gnu::packed]] interrupt_descriptor_table_pointer
+  {
+    /**
+     * @brief Default constructor.
+     */
+    interrupt_descriptor_table_pointer() = default;
+
+    /**
+     * @brief Constructor.
+     */
+    interrupt_descriptor_table_pointer(uint16_t table_length, interrupt_descriptor_table * address);
+
+    /**
+     * @brief Defaulted three-way comparsion operator.
+     */
+    auto operator<=>(interrupt_descriptor_table_pointer const & other) const -> std::strong_ordering = default;
+
+  private:
+    uint16_t table_length = {};  ///< The amount of segment descriptor entries in the global descriptor table - 1.
+    interrupt_descriptor_table address = {};  ///< Non-owning pointer to the IDT base address.
+  };
+
+}  // namespace teachos::arch::context_switching::descriptor_table
+
+#endif  // TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_DESCRIPTOR_TABLE_INTERRUPT_DESCRIPTOR_TABLE_POINTER_HPP
diff --git a/arch/x86_64/include/arch/kernel/cpu/idtr.hpp b/arch/x86_64/include/arch/kernel/cpu/idtr.hpp
new file mode 100644
index 0000000..724fbdf
--- /dev/null
+++ b/arch/x86_64/include/arch/kernel/cpu/idtr.hpp
@@ -0,0 +1,27 @@
+#ifndef TEACHOS_ARCH_X86_64_KERNEL_CPU_IDTR_HPP
+#define TEACHOS_ARCH_X86_64_KERNEL_CPU_IDTR_HPP
+
+#include "arch/context_switching/descriptor_table/global_descriptor_table_pointer.hpp"
+
+#include <bitset>
+#include <cstdint>
+
+namespace teachos::arch::kernel::cpu
+{
+
+  /**
+   * @brief Returns the value in the IDTR register.
+   *
+   * @return Value of IDTR register.
+   */
+  auto store_interrupt_descriptor_table() -> context_switching::descriptor_table::interrupt_descriptor_table_pointer;
+
+  /**
+   * @brief Loads the interrupt_descriptor_table_pointer into the interrupt descriptor table register (IDTR).
+   */
+  auto load_interrupt_descriptor_table(
+      context_switching::descriptor_table::interrupt_descriptor_table_pointer const & idt_pointer) -> void;
+
+}  // namespace teachos::arch::kernel::cpu
+
+#endif  // TEACHOS_ARCH_X86_64_KERNEL_CPU_IDTR_HPP
diff --git a/arch/x86_64/include/arch/kernel/cpu/if.hpp b/arch/x86_64/include/arch/kernel/cpu/if.hpp
new file mode 100644
index 0000000..51f5d9a
--- /dev/null
+++ b/arch/x86_64/include/arch/kernel/cpu/if.hpp
@@ -0,0 +1,14 @@
+#ifndef TEACHOS_ARCH_X86_64_KERNEL_CPU_IF_HPP
+#define TEACHOS_ARCH_X86_64_KERNEL_CPU_IF_HPP
+
+namespace teachos::arch::kernel::cpu
+{
+  /**
+   * @brief Sets the interrupt flag (IF) in the EFLAGS register.
+   * This allows the processor to respond to maskable hardware interrupts.
+   */
+  auto set_interrupt_flag() -> void;
+
+}  // namespace teachos::arch::kernel::cpu
+
+#endif  // TEACHOS_ARCH_X86_64_KERNEL_CPU_IF_HPP
diff --git a/arch/x86_64/include/arch/kernel/cpu/jmp.hpp b/arch/x86_64/include/arch/kernel/cpu/jmp.hpp
new file mode 100644
index 0000000..666174c
--- /dev/null
+++ b/arch/x86_64/include/arch/kernel/cpu/jmp.hpp
@@ -0,0 +1,35 @@
+#ifndef TEACHOS_ARCH_X86_64_KERNEL_CPU_JMP_HPP
+#define TEACHOS_ARCH_X86_64_KERNEL_CPU_JMP_HPP
+
+#include <cstdint>
+
+namespace teachos::arch::kernel::cpu
+{
+  /**
+   * @brief Far jump - A jump to an instruction located in a different segment.
+   */
+  struct [[gnu::packed]] far_pointer
+  {
+    uint64_t offset;   ///< Selector of the segment in which the jump occurs.
+    uint16_t segment;  ///< Address to jump to within the segment.
+  };
+
+  /**
+   * @brief Near jump - A jump to an instruction within the current code segment.
+   *
+   * @param address to jump to.
+   */
+  auto jmp(uint64_t address) -> void;
+
+  /**
+   * @brief Far jump - A jump to an instruction located in a different segment than the current code segment but at the
+   * same privilege level.
+   *
+   * @param segment in which the jump occurs.
+   * @param offset to jump to.
+   */
+  auto jmp(uint64_t segment, uint64_t offset) -> void;
+
+}  // namespace teachos::arch::kernel::cpu
+
+#endif  // TEACHOS_ARCH_X86_64_KERNEL_CPU_JMP_HPP
diff --git a/arch/x86_64/src/boot/boot.s b/arch/x86_64/src/boot/boot.s
index 39bfe33..4fb23e5 100644
--- a/arch/x86_64/src/boot/boot.s
+++ b/arch/x86_64/src/boot/boot.s
@@ -354,7 +354,20 @@ prepare_page_maps:
 .section .boot_text, "ax", @progbits
 .code64
 
+.global segment_register_reload_pointer
+segment_register_reload_pointer:
+    xor %rax, %rax
+    mov %rax, %ss
+    mov %rax, %ds
+    mov %rax, %es
+    mov %rax, %fs
+    mov %rax, %gs
+
+    ret
+
 _transition_to_long_mode:
+    call segment_register_reload_pointer
+
     xor %rax, %rax
     mov %rax, %ss
     mov %rax, %ds
diff --git a/arch/x86_64/src/context_switching/descriptor_table/gate_descriptor.cpp b/arch/x86_64/src/context_switching/descriptor_table/gate_descriptor.cpp
new file mode 100644
index 0000000..ee91e53
--- /dev/null
+++ b/arch/x86_64/src/context_switching/descriptor_table/gate_descriptor.cpp
@@ -0,0 +1,5 @@
+#include "arch/context_switching/descriptor_table/gate_descriptor.hpp"
+
+namespace teachos::arch::context_switching::descriptor_table
+{
+}  // namespace teachos::arch::context_switching::descriptor_table
diff --git a/arch/x86_64/src/context_switching/descriptor_table/global_descriptor_table.cpp b/arch/x86_64/src/context_switching/descriptor_table/global_descriptor_table.cpp
index dccce6b..639b079 100644
--- a/arch/x86_64/src/context_switching/descriptor_table/global_descriptor_table.cpp
+++ b/arch/x86_64/src/context_switching/descriptor_table/global_descriptor_table.cpp
@@ -38,8 +38,8 @@ namespace teachos::arch::context_switching::descriptor_table
     std::bitset<20U> const limit{0xFFFFF};
     access_byte const access_byte{access_level_bitset};
     gdt_flags const gdt_flags{gdt_flags_bitset, limit};
-    segment_descriptor const code_segment{access_byte, gdt_flags, base, limit};
-    return code_segment;
+    segment_descriptor const segment_descriptor{access_byte, gdt_flags, base, limit};
+    return segment_descriptor;
   }
 
   auto create_global_descriptor_table() -> global_descriptor_table
@@ -53,6 +53,7 @@ namespace teachos::arch::context_switching::descriptor_table
         create_segment_descriptor(segment_descriptor_type::CODE_SEGMENT, access_level::USER);
     segment_descriptor const user_data_segment =
         create_segment_descriptor(segment_descriptor_type::DATA_SEGMENT, access_level::USER);
+
     // Task State Segment needs to be kept alive
     static auto tss = new task_state_segment();
     segment_descriptor const tss_descriptor = create_task_state_segment_descriptor(tss);
@@ -85,44 +86,7 @@ namespace teachos::arch::context_switching::descriptor_table
         gdt_pointer == stored_gdt_pointer,
         "[Global Descriptor Table] Loaded GDTR value is not the same as the stored value.");
 
-    // Calculate the offset of the gdt in bytes to the TSS descriptor
-    uint16_t const tss_selector = (gdt.size() - 1) * sizeof(segment_descriptor);
-    kernel::cpu::load_task_register(tss_selector);
-
-    auto const stored_task_register = kernel::cpu::store_task_register();
-    arch::exception_handling::assert(tss_selector == stored_task_register,
-                                     "[Global Descriptor Table] Loaded TR value is not the same as the stored value.");
     return gdt;
   }
 
-  auto reload_cs_register(uint16_t gdt_data_offset) -> void
-  {
-    asm volatile("mov %[input], %%ax\n"
-                 "mov %%ax %%ds\n"  // Data Segment
-                 "mov %%ax %%es\n"  // Extra Segment (used for string operations)
-                 "mov %%ax %%fs\n"  // General-purpose Segment
-                 "mov %%ax %%gs\n"  // General-purpose Segment
-                 "mov %%ax %%ss\n"  // Stack Segment
-                 :                  /* no output from call */
-                 : [input] "r"(gdt_data_offset)
-                 : "ax");
-  }
-
-  auto reload_segment_register(uint16_t gdt_code_offset, uint16_t gdt_data_offset) -> void
-  {
-    /*
-      Whatever you do with the GDT has no effect on the CPU until you load new Segment Selectors into Segment Registers.
-      For most of these registers, the process is as simple as using MOV instructions, but changing the CS register
-      requires code resembling a jump or call to elsewhere, as this is the only way its value is meant to be changed.
-    */
-    auto function = [gdt_data_offset] { reload_cs_register(gdt_data_offset); };
-
-    asm volatile("push %[input]\n"
-                 "lea %[func], %%rax\n"
-                 "push %%rax\n"
-                 "retfq\n"
-                 : /* no output from call */
-                 : [input] "r"(gdt_code_offset), [func] "r"(&function)
-                 : "rax");
-  }
 }  // namespace teachos::arch::context_switching::descriptor_table
diff --git a/arch/x86_64/src/context_switching/descriptor_table/initialization.cpp b/arch/x86_64/src/context_switching/descriptor_table/initialization.cpp
new file mode 100644
index 0000000..4d8b3e3
--- /dev/null
+++ b/arch/x86_64/src/context_switching/descriptor_table/initialization.cpp
@@ -0,0 +1,38 @@
+#include "arch/context_switching/descriptor_table/initialization.hpp"
+
+#include "arch/boot/pointers.hpp"
+#include "arch/exception_handling/assert.hpp"
+#include "arch/kernel/cpu/if.hpp"
+#include "arch/kernel/cpu/jmp.hpp"
+#include "arch/kernel/cpu/tr.hpp"
+
+namespace teachos::arch::context_switching::descriptor_table
+{
+  auto initialize_descriptor_tables() -> descriptor_tables
+  {
+    decltype(auto) global_descriptor_table = context_switching::descriptor_table::initialize_global_descriptor_table();
+
+    // TODO: Replace random construction with return value of initialization.
+    interrupt_descriptor_table idt{};
+    context_switching::descriptor_table::initialize_interrupt_descriptor_table();
+
+    kernel::cpu::jmp((uint64_t)&global_descriptor_table.at(1), boot::segment_register_reload_pointer);
+
+    uint16_t const tss_selector = (global_descriptor_table.size() - 1) << 3;
+    kernel::cpu::load_task_register(tss_selector);
+
+    // Not sure if offset index or offset in bytes is needed!
+    // uint16_t const tss_selector = (gdt.size() - 1) * sizeof(segment_descriptor);
+    // kernel::cpu::load_task_register(tss_selector);
+
+    auto const stored_task_register = kernel::cpu::store_task_register();
+    arch::exception_handling::assert(tss_selector == stored_task_register,
+                                     "[Global Descriptor Table] Loaded TR value is not the same as the stored value.");
+
+    kernel::cpu::set_interrupt_flag();
+
+    descriptor_tables descriptor_tables = {global_descriptor_table, idt};
+    return descriptor_tables;
+  }
+
+}  // namespace teachos::arch::context_switching::descriptor_table
\ No newline at end of file
diff --git a/arch/x86_64/src/context_switching/descriptor_table/interrupt_descriptor_table.cpp b/arch/x86_64/src/context_switching/descriptor_table/interrupt_descriptor_table.cpp
new file mode 100644
index 0000000..9878664
--- /dev/null
+++ b/arch/x86_64/src/context_switching/descriptor_table/interrupt_descriptor_table.cpp
@@ -0,0 +1,10 @@
+#include "arch/context_switching/descriptor_table/interrupt_descriptor_table.hpp"
+
+namespace teachos::arch::context_switching::descriptor_table
+{
+  auto initialize_interrupt_descriptor_table() -> void
+  {
+    // DO NOT
+  }
+
+}  // namespace teachos::arch::context_switching::descriptor_table
diff --git a/arch/x86_64/src/context_switching/descriptor_table/interrupt_descriptor_table_pointer.cpp b/arch/x86_64/src/context_switching/descriptor_table/interrupt_descriptor_table_pointer.cpp
new file mode 100644
index 0000000..b45324d
--- /dev/null
+++ b/arch/x86_64/src/context_switching/descriptor_table/interrupt_descriptor_table_pointer.cpp
@@ -0,0 +1,13 @@
+#include "arch/context_switching/descriptor_table/interrupt_descriptor_table_pointer.hpp"
+
+namespace teachos::arch::context_switching::descriptor_table
+{
+  interrupt_descriptor_table_pointer::interrupt_descriptor_table_pointer(uint16_t table_length,
+                                                                         interrupt_descriptor_table * address)
+      : table_length(table_length)
+      , address(address)
+  {
+    // Nothing to do.
+  }
+
+}  // namespace teachos::arch::context_switching::descriptor_table
diff --git a/arch/x86_64/src/kernel/cpu/idtr.cpp b/arch/x86_64/src/kernel/cpu/idtr.cpp
new file mode 100644
index 0000000..bbf34cb
--- /dev/null
+++ b/arch/x86_64/src/kernel/cpu/idtr.cpp
@@ -0,0 +1,19 @@
+#include "arch/kernel/cpu/idtr.hpp"
+
+#include "arch/context_switching/descriptor_table/interrupt_descriptor_table_pointer.hpp"
+
+namespace teachos::arch::kernel::cpu
+{
+  auto store_global_descriptor_table() -> context_switching::descriptor_table::global_descriptor_table_pointer
+  {
+    context_switching::descriptor_table::interrupt_descriptor_table_pointer current_value{};
+    asm("sidt %[output]" : [output] "=m"(current_value));
+    return current_value;
+  }
+
+  auto load_interrupt_descriptor_table(
+      context_switching::descriptor_table::interrupt_descriptor_table_pointer const & idt_pointer) -> void
+  {
+    asm volatile("lidt %[input]" : /* no output from call */ : [input] "m"(idt_pointer));
+  }
+}  // namespace teachos::arch::kernel::cpu
diff --git a/arch/x86_64/src/kernel/cpu/if.cpp b/arch/x86_64/src/kernel/cpu/if.cpp
new file mode 100644
index 0000000..2a25df5
--- /dev/null
+++ b/arch/x86_64/src/kernel/cpu/if.cpp
@@ -0,0 +1,5 @@
+namespace teachos::arch::kernel::cpu
+{
+  auto set_interrupt_flag() -> void { asm volatile("sti"); }
+
+}  // namespace teachos::arch::kernel::cpu
diff --git a/arch/x86_64/src/kernel/cpu/jmp.cpp b/arch/x86_64/src/kernel/cpu/jmp.cpp
new file mode 100644
index 0000000..009981b
--- /dev/null
+++ b/arch/x86_64/src/kernel/cpu/jmp.cpp
@@ -0,0 +1,16 @@
+#include "arch/kernel/cpu/jmp.hpp"
+
+namespace teachos::arch::kernel::cpu
+{
+  auto jmp(uint64_t address) -> void
+  {
+    asm volatile("jmp *%[input]" : /* no output from call */ : [input] "r"(address));
+  }
+
+  auto jmp(uint64_t segment, uint64_t offset) -> void
+  {
+    far_pointer far_pointer = {offset, static_cast<uint16_t>(segment)};
+    asm volatile("jmp *%0" : : "m"(far_pointer));
+  }
+
+}  // namespace teachos::arch::kernel::cpu
diff --git a/arch/x86_64/src/kernel/main.cpp b/arch/x86_64/src/kernel/main.cpp
index da6d6d3..9433558 100644
--- a/arch/x86_64/src/kernel/main.cpp
+++ b/arch/x86_64/src/kernel/main.cpp
@@ -1,6 +1,9 @@
 #include "arch/kernel/main.hpp"
 
-#include "arch/context_switching/descriptor_table/global_descriptor_table.hpp"
+#include "arch/boot/pointers.hpp"
+#include "arch/context_switching/descriptor_table/initialization.hpp"
+#include "arch/kernel/cpu/if.hpp"
+#include "arch/kernel/cpu/jmp.hpp"
 #include "arch/memory/heap/bump_allocator.hpp"
 #include "arch/memory/heap/global_heap_allocator.hpp"
 #include "arch/memory/main.hpp"
@@ -60,8 +63,7 @@ namespace teachos::arch::kernel
 
     heap_test();
 
-    decltype(auto) global_descriptor_table = context_switching::descriptor_table::initialize_global_descriptor_table();
-    (void)global_descriptor_table.at(1);
-    video::vga::text::write("GDT FILLED", video::vga::text::common_attributes::green_on_black);
+    decltype(auto) descriptor_tables = context_switching::descriptor_table::initialize_descriptor_tables();
+    (void)descriptor_tables;
   }
 }  // namespace teachos::arch::kernel