diff --git a/sdk/xtdk/amd64/ketypes.h b/sdk/xtdk/amd64/ketypes.h
index f296b1e..4ff38f7 100644
--- a/sdk/xtdk/amd64/ketypes.h
+++ b/sdk/xtdk/amd64/ketypes.h
@@ -9,6 +9,11 @@
 #ifndef __XTDK_AMD64_KETYPES_H
 #define __XTDK_AMD64_KETYPES_H
 
+#include <xttypes.h>
+
+
+/* IOPM Definitions */
+#define IO_ACCESS_MAP_NONE                0
 
 /* Static Kernel-Mode address start */
 #define KSEG0_BASE                        0xFFFFF80000000000
@@ -19,4 +24,71 @@
 /* XTOS Kernel stack size */
 #define KERNEL_STACK_SIZE                 0x8000
 
+/* Global Descriptor Table (GDT) entry union definition */
+typedef union _KGDTENTRY
+{
+    struct
+    {
+        USHORT LimitLow;
+        USHORT BaseLow;
+        union
+        {
+            struct
+            {
+                UCHAR BaseMiddle;
+                UCHAR Flags1;
+                UCHAR Flags2;
+                UCHAR BaseHigh;
+            } Bytes;
+            struct {
+                ULONG BaseMiddle:8;
+                ULONG Type:5;
+                ULONG Dpl:2;
+                ULONG Present:1;
+                ULONG LimitHigh:4;
+                ULONG System:1;
+                ULONG LongMode:1;
+                ULONG DefaultBig:1;
+                ULONG Granularity:1;
+                ULONG BaseHigh:8;
+            } Bits;
+        };
+        ULONG BaseUpper;
+        ULONG MustBeZero;
+    };
+    ULONG64 Alignment;
+} KGDTENTRY, *PKGDTENTRY;
+
+/* Interrupt Descriptor Table (IDT) entry union definition */
+typedef union _KIDTENTRY
+{
+    struct
+    {
+        USHORT OffsetLow;
+        USHORT Selector;
+        USHORT IstIndex:3;
+        USHORT Reserved0:5;
+        USHORT Type:5;
+        USHORT Dpl:2;
+        USHORT Present:1;
+        USHORT OffsetMiddle;
+        ULONG OffsetHigh;
+        ULONG Reserved1;
+    };
+    ULONG64 Alignment;
+} KIDTENTRY, *PKIDTENTRY;
+
+/* Task State Segment (TSS) structure definition */
+typedef struct _KTSS
+{
+    ULONG Reserved0;
+    ULONG64 Rsp0;
+    ULONG64 Rsp1;
+    ULONG64 Rsp2;
+    ULONG64 Ist[8];
+    ULONG64 Reserved1;
+    USHORT Reserved2;
+    USHORT IoMapBase;
+} KTSS, *PKTSS;
+
 #endif /* __XTDK_AMD64_KETYPES_H */
diff --git a/sdk/xtdk/amd64/xtstruct.h b/sdk/xtdk/amd64/xtstruct.h
index d976ab0..0998f92 100644
--- a/sdk/xtdk/amd64/xtstruct.h
+++ b/sdk/xtdk/amd64/xtstruct.h
@@ -13,5 +13,10 @@
 /* Architecture-related structures forward references */
 typedef struct _CPUID_REGISTERS CPUID_REGISTERS, *PCPUID_REGISTERS;
 typedef struct _HARDWARE_PTE HARDWARE_PTE, *PHARDWARE_PTE;
+typedef struct _KTSS KTSS, *PKTSS;
+
+/* Architecture-related unions forward references */
+typedef union _KGDTENTRY KGDTENTRY, *PKGDTENTRY;
+typedef union _KIDTENTRY KIDTENTRY, *PKIDTENTRY;
 
 #endif /* __XTDK_AMD64_XTSTRUCT_H */
diff --git a/sdk/xtdk/i686/ketypes.h b/sdk/xtdk/i686/ketypes.h
index de1354e..ad503c4 100644
--- a/sdk/xtdk/i686/ketypes.h
+++ b/sdk/xtdk/i686/ketypes.h
@@ -9,6 +9,15 @@
 #ifndef __XTDK_I686_KETYPES_H
 #define __XTDK_I686_KETYPES_H
 
+#include <xttypes.h>
+
+
+/* IOPM Definitions */
+#define IOPM_COUNT                        1
+#define IOPM_SIZE                         8192
+#define IOPM_FULL_SIZE                    8196
+#define IOPM_ACCESS_MAP_NONE              0
+#define IOPM_DIRECTION_MAP_SIZE           32
 
 /* Static Kernel-Mode address start */
 #define KSEG0_BASE                        0x80000000
@@ -19,4 +28,87 @@
 /* XTOS Kernel stack size */
 #define KERNEL_STACK_SIZE                 0x4000
 
+/* Global Descriptor Table (GDT) entry structure definition */
+typedef struct _KGDTENTRY
+{
+    USHORT LimitLow;
+    USHORT BaseLow;
+    union
+    {
+        struct
+        {
+            UCHAR BaseMiddle;
+            UCHAR Flags1;
+            UCHAR Flags2;
+            UCHAR BaseHigh;
+        } Bytes;
+        struct
+        {
+            ULONG BaseMid:8;
+            ULONG Type:5;
+            ULONG Dpl:2;
+            ULONG Present:1;
+            ULONG LimitHigh:4;
+            ULONG System:1;
+            ULONG Reserved0:1;
+            ULONG DefaultBig:1;
+            ULONG Granularity:1;
+            ULONG BaseHigh:8;
+        } Bits;
+    } HighWord;
+} KGDTENTRY, *PKGDTENTRY;
+
+/* Interrupt Descriptor Table (IDT) entry structure definition */
+typedef struct _KIDTENTRY {
+    USHORT Offset;
+    USHORT Selector;
+    USHORT Access;
+    USHORT ExtendedOffset;
+} KIDTENTRY, *PKIDTENTRY;
+
+/* Interrupt direction access map structure definition */
+typedef struct _KIIO_ACCESS_MAP {
+    UCHAR DirectionMap[IOPM_DIRECTION_MAP_SIZE];
+    UCHAR IoMap[IOPM_FULL_SIZE];
+} KIIO_ACCESS_MAP, *PKIIO_ACCESS_MAP;
+
+/* Task State Segment (TSS) structure definition */
+typedef struct _KTSS {
+    USHORT Backlink;
+    USHORT Reserved0;
+    ULONG Esp0;
+    USHORT Ss0;
+    USHORT Reserved1;
+    ULONG NotUsed1[4];
+    ULONG CR3;
+    ULONG Eip;
+    ULONG EFlags;
+    ULONG Eax;
+    ULONG Ecx;
+    ULONG Edx;
+    ULONG Ebx;
+    ULONG Esp;
+    ULONG Ebp;
+    ULONG Esi;
+    ULONG Edi;
+    USHORT Es;
+    USHORT Reserved2;
+    USHORT Cs;
+    USHORT Reserved3;
+    USHORT Ss;
+    USHORT Reserved4;
+    USHORT Ds;
+    USHORT Reserved5;
+    USHORT Fs;
+    USHORT Reserved6;
+    USHORT Gs;
+    USHORT Reserved7;
+    USHORT LDT;
+    USHORT Reserved8;
+    USHORT Flags;
+    USHORT IoMapBase;
+    KIIO_ACCESS_MAP IoMaps[IOPM_COUNT];
+    UCHAR IntDirectionMap[IOPM_DIRECTION_MAP_SIZE];
+} KTSS, *PKTSS;
+
 #endif /* __XTDK_I686_KETYPES_H */
diff --git a/sdk/xtdk/i686/xtstruct.h b/sdk/xtdk/i686/xtstruct.h
index e01d4cf..5cd8f9a 100644
--- a/sdk/xtdk/i686/xtstruct.h
+++ b/sdk/xtdk/i686/xtstruct.h
@@ -14,5 +14,9 @@
 typedef struct _CPUID_REGISTERS CPUID_REGISTERS, *PCPUID_REGISTERS;
 typedef struct _HARDWARE_PTE HARDWARE_PTE, *PHARDWARE_PTE;
 typedef struct _HARDWARE_PTE_PAE HARDWARE_PTE_PAE, *PHARDWARE_PTE_PAE;
+typedef struct _KGDTENTRY KGDTENTRY, *PKGDTENTRY;
+typedef struct _KIDTENTRY KIDTENTRY, *PKIDTENTRY;
+typedef struct _KIIO_ACCESS_MAP KIIO_ACCESS_MAP, *PKIIO_ACCESS_MAP;
+typedef struct _KTSS KTSS, *PKTSS;
 
 #endif /* __XTDK_I686_XTSTRUCT_H */
diff --git a/sdk/xtdk/xtbase.h b/sdk/xtdk/xtbase.h
index b430ec8..2164546 100644
--- a/sdk/xtdk/xtbase.h
+++ b/sdk/xtdk/xtbase.h
@@ -14,6 +14,9 @@
 #include <xttypes.h>
 
 
+/* Interrupt Request Level (IRQL) */
+typedef UCHAR KIRQL, *PKIRQL;
+
 /* 128-bit buffer containing a unique identifier value */
 typedef struct _GUID
 {