diff --git a/headers/private/kernel/arch/x86_64/arch_kernel.h b/headers/private/kernel/arch/x86_64/arch_kernel.h
index a7e45b34e7..056efafcfa 100644
--- a/headers/private/kernel/arch/x86_64/arch_kernel.h
+++ b/headers/private/kernel/arch/x86_64/arch_kernel.h
@@ -1,6 +1,42 @@
+/*
+ * Copyright 2012, Alex Smith, alex@alex-smith.me.uk.
+ * Distributed under the terms of the MIT License.
+ */
 #ifndef _KERNEL_ARCH_X86_64_KERNEL_H
 #define _KERNEL_ARCH_X86_64_KERNEL_H
 
-#include "../x86/arch_kernel.h"
+
+#ifndef _ASSEMBLER
+#	include <arch/cpu.h>
+#endif
+
+
+// Base of the kernel address space.
+// When compiling the bootloader, KERNEL_BASE is set to the x86 base address,
+// the correct 64-bit addresses are calculated differently.
+// For the kernel, this is the base of the kernel address space. This is NOT
+// the address where the kernel is loaded to: the kernel is loaded in the top
+// 2GB of the virtual address space as required by GCC's kernel code model.
+// The whole kernel address space is the top 512GB of the address space.
+#ifdef _BOOT_MODE
+# define KERNEL_BASE	0x80000000
+#else
+# define KERNEL_BASE	0xFFFFFF8000000000
+#endif
+
+#define KERNEL_SIZE		0x8000000000
+#define KERNEL_TOP  	(KERNEL_BASE + (KERNEL_SIZE - 1))
+
+
+// Userspace address space layout.
+#define USER_BASE		0x0
+#define USER_BASE_ANY	0x100000
+#define USER_SIZE		0x800000000000
+#define USER_TOP		(USER_BASE + USER_SIZE)
+
+#define KERNEL_USER_DATA_BASE	0x7FFFEFFF0000
+#define USER_STACK_REGION		0x7FFFF0000000
+#define USER_STACK_REGION_SIZE	(USER_TOP - USER_STACK_REGION)
+
 
 #endif	/* _KERNEL_ARCH_X86_64_KERNEL_H */