diff --git a/kaleid/kernel/mm/gdt.c b/kaleid/kernel/mm/gdt.c
new file mode 100644
index 0000000..ae395a6
--- /dev/null
+++ b/kaleid/kernel/mm/gdt.c
@@ -0,0 +1,50 @@
+//----------------------------------------------------------------------------//
+//                           GNU GPL OS/K                                     //
+//                                                                            //
+//  Desc:         Mapping and checking memory related functions               //
+//                                                                            //
+//                                                                            //
+//  Copyright © 2018-2019 The OS/K Team                                       //
+//                                                                            //
+//  This file is part of OS/K.                                                //
+//                                                                            //
+//  OS/K is free software: you can redistribute it and/or modify              //
+//  it under the terms of the GNU General Public License as published by      //
+//  the Free Software Foundation, either version 3 of the License, or         //
+//  any later version.                                                        //
+//                                                                            //
+//  OS/K is distributed in the hope that it will be useful,                   //
+//  but WITHOUT ANY WARRANTY//without even the implied warranty of            //
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the             //
+//  GNU General Public License for more details.                              //
+//                                                                            //
+//  You should have received a copy of the GNU General Public License         //
+//  along with OS/K.  If not, see <https://www.gnu.org/licenses/>.            //
+//----------------------------------------------------------------------------//
+
+#include <kernel/mm.h>
+
+// The Gdt
+GdtEntry_t gdtEntries[5];
+GdtPtr_t gdtPtr;
+
+void MmInitGdt(void)
+{
+    gdtPtr.limit = (sizeof(gdt_entry_t) * 5) - 1;
+    gdtPtr.base  = (uint)&gdt_entries;
+}
+
+static void MmSetGdtEntry(int index, uint base, uint limit, uchar access,
+                          uchar granularity)
+{
+    gdtEntries[num].lowBase      = (base & 0xFFFF);
+    gdtEntries[num].middleBase   = (base >> 16) & 0xFF;
+    gdtEntries[num].highBase     = (base >> 24) & 0xFF;
+
+    gdtEntries[num].lowLimit     = (limit & 0xFFFF);
+    gdtEntries[num].granularity  = (limit >> 16) & 0x0F;
+
+    gdtEntries[num].granularity |= gran & 0xF0;
+    gdtEntries[num].access       = access;
+}
+