diff --git a/Makefile.example b/Makefile.example
index da2779da..17346871 100644
--- a/Makefile.example
+++ b/Makefile.example
@@ -1,5 +1,6 @@
 TOPDIR = $(shell pwd)
 ARCH = x86
+# For 64bit support, you have define BIT as 64
 BIT=32
 NAME = metalsvm
 LWIPDIRS = lwip/src/arch lwip/src/api lwip/src/core lwip/src/core/ipv4 lwip/src/netif
@@ -32,23 +33,29 @@ READELF_FOR_TARGET = $(CROSSCOMPREFIX)readelf
 MAKE = make
 RM = rm -rf
 NASM = nasm
+# For 64bit code, you have to use qemu-system-x86_64
 QEMU = qemu-system-i386
 EMU = qemu
 GDB = gdb
 
+# For 64bit support, you have to define -felf64 instead of -felf32
 NASMFLAGS = -felf32 -g -i$(TOPDIR)/include/metalsvm/
 INCLUDE = -I$(TOPDIR)/include -I$(TOPDIR)/arch/$(ARCH)/include -I$(TOPDIR)/lwip/src/include -I$(TOPDIR)/lwip/src/include/ipv4 -I$(TOPDIR)/drivers
+# For 64bit support, you have to define "-m64 -mno-red-zone" instead of "-m32 -march=i586"
 # Compiler options for final code
-CFLAGS = -g -m32 -march=i586 -Wall -O2 -fno-builtin -fstrength-reduce -fomit-frame-pointer -finline-functions -nostdinc $(INCLUDE) $(STACKPROT)
+CFLAGS = -g -m32 -march=i586 -Wall -O2 -fstrength-reduce -fomit-frame-pointer -finline-functions -ffreestanding $(INCLUDE) $(STACKPROT)
 # Compiler options for debuging
-#CFLAGS = -g -O -m32 -march=i586 -Wall -fno-builtin -DWITH_FRAME_POINTER -nostdinc $(INCLUDE) $(STACKPROT)
+#CFLAGS = -g -O -m32 -march=i586 -Wall -DWITH_FRAME_POINTER -ffreestanding $(INCLUDE) $(STACKPROT)
 ARFLAGS = rsv
 LDFLAGS = -T link$(BIT).ld -z max-page-size=4096 --defsym __BUILD_DATE=$(shell date +'%Y%m%d') --defsym __BUILD_TIME=$(shell date +'%H%M%S')
 STRIP_DEBUG = --strip-debug
 KEEP_DEBUG = --only-keep-debug
 OUTPUT_FORMAT = -O elf32-i386
+# For 64bit support, you have to define -m64 instead of "-m32 -march=i586"
 CFLAGS_FOR_NEWLIB = -m32 -march=i586 -O2 $(STACKPROT)
+# For 64bit support, you have to define -m64 instead of "-m32 -march=i586"
 LDFLAGS_FOR_NEWLIB = -m32 -march=i586
+# For 64bit support, you have to define -felf64 instead of -felf32
 NASMFLAGS_FOR_NEWLIB = -felf32
 
 # Prettify output
diff --git a/arch/x86/include/asm/gdt.h b/arch/x86/include/asm/gdt.h
index fb4bd4c1..8df3115f 100644
--- a/arch/x86/include/asm/gdt.h
+++ b/arch/x86/include/asm/gdt.h
@@ -36,35 +36,37 @@ extern "C" {
 #endif
 
 /// This segment is a data segment
-#define GDT_FLAG_DATASEG        0x02
+#define GDT_FLAG_DATASEG	0x02
 /// This segment is a code segment
-#define GDT_FLAG_CODESEG        0x0a
-#define GDT_FLAG_TSS            0x09
+#define GDT_FLAG_CODESEG	0x0a
+#define GDT_FLAG_TSS		0x09
 #define GDT_FLAG_TSS_BUSY	0x02
 
-#define GDT_FLAG_SEGMENT        0x10
+#define GDT_FLAG_SEGMENT	0x10
 /// Privilege level: Ring 0 
-#define GDT_FLAG_RING0          0x00
+#define GDT_FLAG_RING0		0x00
 /// Privilege level: Ring 1
-#define GDT_FLAG_RING1          0x20
+#define GDT_FLAG_RING1		0x20
 /// Privilege level: Ring 2 
-#define GDT_FLAG_RING2          0x40
+#define GDT_FLAG_RING2		0x40
 /// Privilege level: Ring 3 
-#define GDT_FLAG_RING3          0x60
+#define GDT_FLAG_RING3		0x60
 /// Segment is present
-#define GDT_FLAG_PRESENT        0x80
+#define GDT_FLAG_PRESENT	0x80
 /** 
  * @brief Granularity of segment limit 
  * - set: segment limit unit is 4 KB (page size)
  * - not set: unit is bytes
  */
-#define GDT_FLAG_4K_GRAN        0x80
+#define GDT_FLAG_4K_GRAN	0x80
 /**
  * @brief Default operand size 
  * - set: 32 bit
  * - not set: 16 bit
  */
-#define GDT_FLAG_32_BIT         0x40
+#define GDT_FLAG_16_BIT		0x00
+#define GDT_FLAG_32_BIT		0x40
+#define GDT_FLAG_64_BIT		0x20
 
 /** @brief Defines a GDT entry 
  *
@@ -74,17 +76,17 @@ extern "C" {
  */
 typedef struct {
 	/// Lower 16 bits of limit range
-	unsigned short limit_low;
+	uint16_t limit_low;
 	/// Lower 16 bits of base address
-	unsigned short base_low;
+	uint16_t base_low;
 	/// middle 8 bits of base address
-	unsigned char base_middle;
+	uint8_t base_middle;
 	/// Access bits
-	unsigned char access;
+	uint8_t access;
 	/// Granularity bits
-	unsigned char granularity;
+	uint8_t granularity;
 	/// Higher 8 bits of base address
-	unsigned char base_high;
+	uint8_t base_high;
 } __attribute__ ((packed)) gdt_entry_t;
 
 /** @brief defines the GDT pointer structure
@@ -93,9 +95,9 @@ typedef struct {
  */
 typedef struct {
 	/// Size of the table in bytes (not the number of entries!)
-	unsigned short limit;
+	uint16_t limit;
 	/// Address of the table
-	unsigned int base;
+	size_t base;
 } __attribute__ ((packed)) gdt_ptr_t;
 
 /// Defines the maximum number of GDT entries
@@ -115,16 +117,6 @@ typedef struct {
  */
 void gdt_install(void);
 
-/** @brief Configures and returns a GDT descriptor with chosen attributes
- *
- * Just feed this function with address, limit and the flags 
- * you have seen in idt.h
- *
- * @return a preconfigured gdt descriptor
- */
-gdt_entry_t configure_gdt_entry(unsigned long base, unsigned long limit,
-		unsigned char access, unsigned char gran);
-
 #ifdef __cplusplus
 }
 #endif
diff --git a/arch/x86/include/asm/idt.h b/arch/x86/include/asm/idt.h
index a30cddb1..f8665792 100644
--- a/arch/x86/include/asm/idt.h
+++ b/arch/x86/include/asm/idt.h
@@ -71,15 +71,21 @@ extern "C" {
  */
 typedef struct {
 	/// Handler function's lower 16 address bits
-	unsigned short base_lo;
+	uint16_t base_lo;
 	/// Handler function's segment selector.
-	unsigned short sel;
+	uint16_t sel;
 	/// These bits are reserved by Intel
-	unsigned char always0;
+	uint8_t always0;
 	/// These 8 bits contain flags. Exact use depends on the type of interrupt gate.
-	unsigned char flags;
+	uint8_t flags;
 	/// Higher 16 bits of handler function's base address
-	unsigned short base_hi;
+	uint16_t base_hi;
+#ifdef CONFIG_X86_64
+	/// In 64 bit mode, the "highest" 32 bits of the handler function's base address
+	uint32_t base_hi64;
+	/// resvered entries
+	uint32_t reserved;
+#endif
 } __attribute__ ((packed)) idt_entry_t;
 
 /** @brief Defines the idt pointer structure.
@@ -89,9 +95,9 @@ typedef struct {
  */
 typedef struct {
 	/// Size of the IDT in bytes (not the number of entries!)
-	unsigned short limit;
+	uint16_t limit;
 	/// Base address of the IDT
-	unsigned int base;
+	size_t base;
 } __attribute__ ((packed)) idt_ptr_t;
 
 /** @brief Installs IDT
@@ -113,16 +119,6 @@ void idt_install(void);
 void idt_set_gate(unsigned char num, size_t base, unsigned short sel,
 		  unsigned char flags);
 
-/** @brief Configures and returns a IDT entry with chosen attributes
- *
- * Just feed this function with base, selector and the flags
- * you have seen in idt.h
- *
- * @return a preconfigured idt descriptor
- */
-idt_entry_t configure_idt_entry(size_t base, unsigned short sel,
-		  unsigned char flags);
-
 #ifdef __cplusplus
 }
 #endif
diff --git a/arch/x86/include/asm/page.h b/arch/x86/include/asm/page.h
index 5c5d5960..d02242fd 100644
--- a/arch/x86/include/asm/page.h
+++ b/arch/x86/include/asm/page.h
@@ -93,7 +93,7 @@
 /** @brief Page table structure
  *
  * This structure keeps page table entries.\n
- * A page table consists of 1024 entries.
+ * On a 32bit system, a page table consists normally of 1024 entries.
  */
 typedef struct page_table
 {
@@ -104,7 +104,7 @@ typedef struct page_table
 /** @brief Page directory structure
  *
  * This structure keeps page directory entries.\
- * A page directory consists of 1024 entries.
+ * On a 32bit system, a page directory consists normally of 1024 entries.
  */
 typedef struct page_dir
 {
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index e55f5c10..cfa6544e 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -335,7 +335,9 @@ uint32_t read_eip(void);
 inline static int system_init(void)
 {
 	gdt_install();
+#ifdef CONFIG_X86_32
 	apic_init();
+#endif
 #ifdef CONFIG_PCI
 	pci_init();
 #endif
diff --git a/arch/x86/include/asm/stddef.h b/arch/x86/include/asm/stddef.h
index 50d3258c..e83032e1 100644
--- a/arch/x86/include/asm/stddef.h
+++ b/arch/x86/include/asm/stddef.h
@@ -85,33 +85,79 @@ typedef unsigned int wint_t;
  * All the interrupt handler routines use this type for their only parameter.
  */
 struct state {
+#ifdef CONFIG_X86_32
 	/// EDI register
-	unsigned int edi;
+	uint32_t edi;
 	/// ESI register
-	unsigned int esi;
+	uint32_t esi;
 	/// EBP register
-	unsigned int ebp;
+	uint32_t ebp;
 	/// ESP register
-	unsigned int esp;
+	uint32_t esp;
 	/// EBX register 
-	unsigned int ebx;
+	uint32_t ebx;
 	/// EDX register
-	unsigned int edx;
+	uint32_t edx;
 	/// ECX register
-	unsigned int ecx;
+	uint32_t ecx;
 	/// EAX register
-	unsigned int eax;		/* pushed by 'pusha' */
+	uint32_t eax;		/* pushed by 'pusha' */
 
 	/// Interrupt number
-	unsigned int int_no;
+	uint32_t int_no;
 	
 	// pushed by the processor automatically
-	unsigned int error;
-	unsigned int eip;
-	unsigned int cs;
-	unsigned int eflags;
-	unsigned int useresp;
-	unsigned int ss;
+	uint32_t error;
+	uint32_t eip;
+	uint32_t cs;
+	uint32_t eflags;
+	uint32_t useresp;
+	uint32_t ss;
+#elif defined(CONFIG_X86_64)
+	/// R15 register
+	uint64_t r15;
+	/// R14 register
+	uint64_t r14;
+	/// R13 register
+	uint64_t r13;
+	/// R12 register
+	uint64_t r12;
+	/// R11 register
+	uint64_t r11;
+	/// R10 register
+	uint64_t r10;
+	/// R9 register
+	uint64_t r9;
+	/// R8 register
+	uint64_t r8;
+	/// RDI register
+	uint64_t rdi;
+	/// RSI register
+	uint64_t rsi;
+	/// RBP register
+	uint64_t rbp;
+	/// (pseudo) RSP register
+	uint64_t rsp;
+	/// RBX register
+	uint64_t rbx;
+	/// RDX register
+	uint64_t rdx;
+	/// RCX register
+	uint64_t rcx;
+	/// RAX register
+	uint64_t rax;
+
+	/// Interrupt number
+	uint64_t int_no;
+
+	// pushed by the processor automatically
+	uint64_t error;
+	uint64_t rip;
+	uint64_t cs;
+	uint64_t rflags;
+	uint64_t userrsp;
+	uint64_t ss;
+#endif
 };
 
 uint32_t apic_cpu_id(void);
diff --git a/arch/x86/include/asm/string.h b/arch/x86/include/asm/string.h
index 66f5e617..ee39ff4a 100644
--- a/arch/x86/include/asm/string.h
+++ b/arch/x86/include/asm/string.h
@@ -96,11 +96,12 @@ inline static void *memcpy(void *dest, const void *src, size_t count)
  */
 inline static void *memcpy(void* dest, const void *src, size_t count)
 {
-	int32_t i, j, k;
+	size_t i, j, k;
 
 	if (BUILTIN_EXPECT(!dest || !src, 0))
 		return dest;
 
+#ifdef CONFIG_X86_32
 	asm volatile (
 		"cld; rep movsl\n\t"
 		"movl %4, %%ecx\n\t" 
@@ -108,6 +109,15 @@ inline static void *memcpy(void* dest, const void *src, size_t count)
 		"rep movsb\n\t" 
 		: "=&c"(i), "=&D"(j), "=&S"(k) 
 		: "0"(count/4), "g"(count), "1"(dest), "2"(src) : "memory","cc");
+#elif defined(CONFIG_X86_64)
+	asm volatile (
+		"cld; rep movsq\n\t"
+		"movq %4, %%rcx\n\t"
+		"andq $7, %%rcx\n\t"
+		"rep movsb\n\t"
+		: "=&c"(i), "=&D"(j), "=&S"(k)
+		: "0"(count/8), "g"(count), "1"(dest), "2"(src) : "memory","cc");
+#endif
 
 	return dest;
 }
@@ -128,7 +138,7 @@ inline static void *memcpy(void* dest, const void *src, size_t count)
  */
 inline static void *memset(void* dest, int val, size_t count)
 {
-	int32_t i, j;
+	size_t i, j;
 
 	if (BUILTIN_EXPECT(!dest, 0))
 		return dest;
@@ -155,7 +165,7 @@ inline static void *memset(void* dest, int val, size_t count)
  */
 inline static void *memset(void* dest, int val, size_t count)
 {
-	int32_t i, j;
+	size_t i, j;
 
 	if (BUILTIN_EXPECT(!dest, 0))
 		return dest;
@@ -184,15 +194,22 @@ inline static void *memset(void* dest, int val, size_t count)
 inline static size_t strlen(const char* str)
 {
 	size_t len = 0;
-	uint32_t i, j;
+	size_t i, j;
 
 	if (BUILTIN_EXPECT(!str, 0))
 		return len;
 
+#ifdef CONFIG_X86_32
 	asm volatile("not %%ecx; cld; repne scasb; not %%ecx; dec %%ecx"
 		: "=&c"(len), "=&D"(i), "=&a"(j)
 		: "2"(0), "1"(str), "0"(len)
 		: "memory","cc");
+#elif defined(CONFIG_X86_64)
+	asm volatile("not %%rcx; cld; repne scasb; not %%rcx; dec %%rcx"
+		: "=&c"(len), "=&D"(i), "=&a"(j)
+		: "2"(0), "1"(str), "0"(len)
+		: "memory","cc");
+#endif
 
 	return len;
 }
diff --git a/arch/x86/include/asm/tasks.h b/arch/x86/include/asm/tasks.h
index a5367512..6761b240 100644
--- a/arch/x86/include/asm/tasks.h
+++ b/arch/x86/include/asm/tasks.h
@@ -95,11 +95,11 @@ static inline int jump_to_user_code(uint32_t ep, uint32_t stack)
 	asm volatile ("mov %0, %%ds; mov %0, %%fs; mov %0, %%gs; mov %0, %%es" :: "r"(0x23));
 	asm volatile ("push $0x23; push %0; push $0x1B; push %1" :: "r"(stack), "r"(ep));
 	asm volatile ("lret" ::: "cc");
-#else
-#warning Currently, not supported!
-#endif
 
 	return 0;
+#else
+	return -22;
+#endif
 }
 
 /** @brief determines the stack of a specific task
diff --git a/arch/x86/include/asm/tss.h b/arch/x86/include/asm/tss.h
index 9e905449..17b2e8ab 100644
--- a/arch/x86/include/asm/tss.h
+++ b/arch/x86/include/asm/tss.h
@@ -35,6 +35,7 @@ extern "C" {
 /** @brief The tast state segment structure
  */
 typedef struct {
+#ifdef CONFIG_X86_32
 	uint16_t	backlink, __blh;
 	uint32_t	esp0;
 	uint16_t	ss0, __ss0h;
@@ -55,6 +56,24 @@ typedef struct {
 	uint16_t	gs, __gsh;
 	uint16_t	ldt, __ldth;
 	uint16_t	trace, bitmap;
+#endif
+#ifdef CONFIG_X86_64
+	uint16_t	res0, res1;	// reserved entries
+	uint64_t	rsp0;
+	uint64_t	rsp1;
+	uint64_t	rsp2;
+	uint32_t	res2, res3;	// reserved entries
+	uint64_t	ist_rsp1;
+	uint64_t	ist_rsp2;
+	uint64_t	ist_rsp3;
+	uint64_t	ist_rsp4;
+	uint64_t	ist_rsp5;
+	uint64_t	ist_rsp6;
+	uint64_t	ist_rsp7;
+	uint32_t	res4;		// reserved entries
+	uint32_t	res5;		// reserved entries
+	uint16_t	res6, bitmap;
+#endif
 } __attribute__ ((packed)) tss_t;
 
 #ifdef __cplusplus
diff --git a/arch/x86/kernel/entry32.asm b/arch/x86/kernel/entry32.asm
index c9c0f4dc..49e30351 100644
--- a/arch/x86/kernel/entry32.asm
+++ b/arch/x86/kernel/entry32.asm
@@ -66,11 +66,13 @@ ALIGN 4
 stublet:
 ; initialize stack pointer.
     mov esp, [default_stack_pointer]
+; save pointer to the multiboot structure
+    push ebx 
 ; initialize cpu features
     call cpu_init
 ; interpret multiboot information
     extern multiboot_init
-    push ebx
+; pointer to the multiboot structure is already pushed
     call multiboot_init
     add esp, 4
 
@@ -769,8 +771,8 @@ switch_context:
     pushf                       ; EFLAGS
     push DWORD 0x8              ; CS
     push DWORD rollback         ; EIP
-    push DWORD 0                ; Interrupt number
-    push DWORD 0xc0edbabe       ; Error code
+    push DWORD 0x0              ; Interrupt number
+    push DWORD 0x00edbabe       ; Error code
     pusha                       ; Registers...
 
     jmp common_switch
diff --git a/arch/x86/kernel/entry64.asm b/arch/x86/kernel/entry64.asm
index bb06c3b1..5a35099a 100644
--- a/arch/x86/kernel/entry64.asm
+++ b/arch/x86/kernel/entry64.asm
@@ -91,17 +91,17 @@ SECTION .data
 ; create default page tables for the 64bit kernel
 global boot_pgd ; aka PML4
 ALIGN 4096 ; of course, the page tables have to be page aligned
-NOPTS equ 2
+NOPTS equ 512
 boot_pgd times 512 DQ 0
-pdpt times 512 DQ 0
-pd times 512 DQ 0
-pt times (NOPTS*512) DQ 0
+boot_pdpt times 512 DQ 0
+boot_pd times 512 DQ 0
+boot_pt times (NOPTS*512) DQ 0
 
 SECTION .text
 ALIGN 4
 stublet:
     mov esp, startup_stack-4
-    push ebx ; save pointer to multiboot structure
+    push ebx ; save pointer to the multiboot structure
     mov eax, cr0
 ; enable caching, disable paging and fpu emulation
     and eax, 0x1ffffffb
@@ -144,13 +144,13 @@ stublet:
     mov cr3, edi
 
 ; So lets make PML4T[0] point to the PDPT and so on:
-    mov DWORD [edi], pdpt         ; Set the double word at the destination index to pdpt.
+    mov DWORD [edi], boot_pdpt    ; Set the double word at the destination index to pdpt.
     or DWORD [edi], 0x00000003    ; Set present and writeable bit
-    mov edi, pdpt
-    mov DWORD [edi], pd           ; Set the double word at the destination index to pd.
+    mov edi, boot_pdpt
+    mov DWORD [edi], boot_pd      ; Set the double word at the destination index to pd.
     or DWORD [edi], 0x00000003    ; Set present and writeable bit
-    mov edi, pd
-    mov ebx, pt
+    mov edi, boot_pd
+    mov ebx, boot_pt
     mov ecx, NOPTS
 L0:
     mov DWORD [edi], ebx          ; Set the double word at the destination index to pt.
@@ -162,16 +162,26 @@ L0:
     ; map the VGA address into the virtual address space
     mov edi, 0xB8000
     shr edi, 9   ; (edi >> 12) * 8
-    add edi, pt
+    add edi, boot_pt
     mov ebx, 0xB8000
     or ebx, 0x00000003
     mov DWORD [edi], ebx
 
+    ; map multiboot structure into the virtual address space
+    mov edi, [esp]
+    and edi, 0xFFFFF000
+    shr edi, 9   ; (edi >> 12) * 8
+    add edi, boot_pt
+    mov ebx, [esp]
+    and ebx, 0xFFFFF000
+    or ebx, 0x00000003
+    mov DWORD [edi], ebx
+
     extern kernel_start           ; defined in linker script
     extern kernel_end
     mov edi, kernel_start
     shr edi, 9   ; (kernel_start >> 12) * 8
-    add edi, pt
+    add edi, boot_pt
     mov ebx, kernel_start
     or ebx, 0x00000003
     mov ecx, kernel_end           ; determine kernel size in number of pages
@@ -246,22 +256,12 @@ cpu_init:
 ;    mov cr4, eax
 ;    ret
 
-; This will set up our new segment registers. We need to do
-; something special in order to set CS. We do what is called a
-; far jump. A jump that includes a segment as well as an offset.
-; This is declared in C as 'extern void gdt_flush();'
+; This will set up our new segment registers and is declared in 
+; C as 'extern void gdt_flush();'
 global gdt_flush
 extern gp
 gdt_flush:
-;    lgdt [gp]
-;    mov ax, 0x10
-;    mov ds, ax
-;    mov es, ax
-;    mov fs, ax
-;    mov gs, ax
-;    mov ss, ax
-;    jmp 0x08:flush2
-flush2:
+    lgdt [gp]
     ret
 
 ; determines the current instruction pointer (after the jmp)
@@ -603,7 +603,7 @@ isrsyscall:
     push rdi
     push rsi
     push rbp
-    push Qword 0
+    push rsp
     push rbx
     push rdx
     push rcx
@@ -616,7 +616,7 @@ isrsyscall:
     pop rcx
     pop rdx
     pop rbx
-    add rsp, 1*8
+    add rsp, 8
     pop rbp
     pop rsi
     pop rdi
@@ -627,7 +627,7 @@ isrsyscall:
     pop r12
     pop r13
     pop r14
-    iret
+    iretq
 
 global irq0
 global irq1
@@ -926,17 +926,20 @@ ALIGN 8
 switch_context:
     ; create on the stack a pseudo interrupt
     ; afterwards, we switch to the task with iret
-    mov rax, [rdi]              ; rdi contains the address to store the old rsp
-    pushf                       ; EFLAGS
-    push QWORD 0x8              ; CS
+    mov rax, rdi                ; rdi contains the address to store the old rsp
+    push QWORD 0x10             ; SS
+    push rsp                    ; RSP
+    add QWORD [rsp], 8*1
+    pushf                       ; RFLAGS
+    push QWORD 0x08             ; CS
     push QWORD rollback         ; RIP
-    push QWORD 0                ; Interrupt number
-    push QWORD 0x0edbabe       ; Error code
+    push QWORD 0x00             ; Interrupt number
+    push QWORD 0x00edbabe       ; Error code
     push rax
     push rcx
     push rdx
     push rbx
-    push Qword 0
+    push rsp
     push rbp
     push rsi
     push rdi
@@ -961,7 +964,7 @@ common_stub:
     push rcx
     push rdx
     push rbx
-    push Qword 0
+    push rsp
     push rbp
     push rsi
     push rdi
@@ -994,7 +997,7 @@ common_switch:
 %else
     xor rax, rax
 %endif
-    add eax, task_state_segments
+    add rax, task_state_segments
     ; set rsp0 in TSS
     mov [rax+4], rsp
 
@@ -1013,13 +1016,13 @@ no_context_switch:
     pop rdi
     pop rsi
     pop rbp
-    add rsp, 1*8
+    add rsp, 8
     pop rbx
     pop rdx
     pop rcx
     pop rax
 
     add rsp, 16
-    iret
+    iretq
 
 SECTION .note.GNU-stack noalloc noexec nowrite progbits
diff --git a/arch/x86/kernel/gdt.c b/arch/x86/kernel/gdt.c
index 84251c3b..ebd73536 100644
--- a/arch/x86/kernel/gdt.c
+++ b/arch/x86/kernel/gdt.c
@@ -61,8 +61,9 @@ size_t get_stack(uint32_t id)
 	return (size_t) kstacks[id] + KERNEL_STACK_SIZE - sizeof(size_t);
 }
 
-int register_task(task_t* task) {
-        uint16_t sel;
+int register_task(task_t* task) 
+{
+	uint16_t sel;
 
 	sel = (CORE_ID+5) << 3;
 	asm volatile ("mov %0, %%ax; ltr %%ax" : : "ir"(sel) : "%eax");
@@ -128,8 +129,9 @@ int create_default_frame(task_t* task, entry_point_t ep, void* arg)
 {
 	uint16_t cs = 0x08;
 	uint32_t id;
-	uint32_t *stack;
+	size_t *stack;
 	struct state *stptr;
+	size_t state_size;
 
 	if (BUILTIN_EXPECT(!task, 0))
 		return -EINVAL;	
@@ -137,17 +139,18 @@ int create_default_frame(task_t* task, entry_point_t ep, void* arg)
 
 	memset(kstacks[id], 0xCD, KERNEL_STACK_SIZE);
 
-#ifdef CONFIG_X86_32
 	/* The difference between setting up a task for SW-task-switching
 	 * and not for HW-task-switching is setting up a stack and not a TSS.
 	 * This is the stack which will be activated and popped off for iret later.
 	 */
-	stack = (uint32_t*) (kstacks[id] + KERNEL_STACK_SIZE - sizeof(uint32_t));
+	stack = (size_t*) (kstacks[id] + KERNEL_STACK_SIZE - sizeof(size_t));
 
 	/* The next three things on the stack are a marker for debugging purposes, ... */
 	*stack-- = 0xDEADBEEF;
+#ifdef CONFIG_X86_32
 	/* the first-function-to-be-called's arguments, ... */
 	*stack-- = (size_t) arg;
+#endif
 	/* and the "caller" we shall return to.
 	 * This procedure cleans the task after exit. */
 	*stack = (size_t) leave_kernel_task;
@@ -156,58 +159,71 @@ int create_default_frame(task_t* task, entry_point_t ep, void* arg)
 	 * The stack must look like the stack of a task which was
 	 * scheduled away previously. */
 
-	stack = (uint32_t*) ((size_t) stack - sizeof(struct state) + 2*sizeof(size_t));
+	/* In 64bit mode, he stack pointer (SS:RSP) is pushed unconditionally on interrupts.
+	 * In legacy modes, this push is conditional and based on a change in current privilege level (CPL).*/
+#ifdef CONFIG_X86_32
+	state_size = sizeof(struct state) - 2*sizeof(size_t);
+#else
+	state_size = sizeof(struct state);
+#endif
+	stack = (size_t*) ((size_t) stack - state_size);
 
 	stptr = (struct state *) stack;
-	memset(stptr, 0x00, sizeof(struct state) - 2*sizeof(size_t));
-	stptr->esp = (size_t)stack + sizeof(struct state) - 2*sizeof(size_t);
+	memset(stptr, 0x00, state_size);
+#ifdef CONFIG_X86_32
+	stptr->esp = (size_t)stack + state_size;
+#else
+	stptr->rsp = (size_t)stack + state_size;
+	/* the first-function-to-be-called's arguments, ... */
+	stptr->rdi = (size_t) arg;
+#endif
 	stptr->int_no = 0xB16B00B5;
 	stptr->error =  0xC03DB4B3;
 
 	/* The instruction pointer shall be set on the first function to be called
 	 * after IRETing */
-	stptr->eip = (uint32_t)ep;
+#ifdef CONFIG_X86_32
+	stptr->eip = (size_t)ep;
+#else
+	stptr->rip = (size_t)ep;
+#endif
 	stptr->cs = cs;
+#ifdef CONFIG_X86_32
 	stptr->eflags = 0x1202;
 	// the creation of a kernel tasks didn't change the IOPL level
 	// => useresp & ss is not required
-
+#else
+	stptr->rflags = 0x1202;
+	stptr->ss = 0x10;
+	stptr->userrsp = stptr->rsp;
+#endif
 
 	/* Set the task's stack pointer entry to the stack we have crafted right now. */
 	task->stack = (size_t*)stack;
-#else
-#warning Currently, not supported
-	return -1;
-#endif
 
 	return 0;
 }
 
-/* Setup a descriptor in the Global Descriptor Table */
+/** @brief Configures GDT descriptor with chosen attributes
+ *
+ * Just feed this function with address, limit and the flags 
+ * you have seen in gdt.h
+ */
 static void gdt_set_gate(int num, unsigned long base, unsigned long limit,
-			  unsigned char access, unsigned char gran)
+			unsigned char access, unsigned char gran)
 {
-	gdt[num] = configure_gdt_entry(base, limit, access, gran);
-}
-
-gdt_entry_t configure_gdt_entry(unsigned long base, unsigned long limit,
-		unsigned char access, unsigned char gran)
-{
-	gdt_entry_t desc;
 	/* Setup the descriptor base address */
-	desc.base_low = (base & 0xFFFF);
-	desc.base_middle = (base >> 16) & 0xFF;
-	desc.base_high = (base >> 24) & 0xFF;
+	gdt[num].base_low = (base & 0xFFFF);
+	gdt[num].base_middle = (base >> 16) & 0xFF;
+	gdt[num].base_high = (base >> 24) & 0xFF;
 
 	/* Setup the descriptor limits */
-	desc.limit_low = (limit & 0xFFFF);
-	desc.granularity = ((limit >> 16) & 0x0F);
+	gdt[num].limit_low = (limit & 0xFFFF);
+	gdt[num].granularity = ((limit >> 16) & 0x0F);
 
 	/* Finally, set up the granularity and access flags */
-	desc.granularity |= (gran & 0xF0);
-	desc.access = access;
-
-	return desc;
+	gdt[num].granularity |= (gran & 0xF0);
+	gdt[num].access = access;
 }
 
 /* 
@@ -219,13 +235,21 @@ gdt_entry_t configure_gdt_entry(unsigned long base, unsigned long limit,
  */
 void gdt_install(void)
 {
-	unsigned int i;
+	unsigned int i, mode;
 
 	memset(task_state_segments, 0x00, MAX_CORES*sizeof(tss_t));
 
+#ifdef CONFIG_X86_32
+	mode = GDT_FLAG_32_BIT;
+#elif defined(CONFIG_X86_64)
+	mode = GDT_FLAG_64_BIT;
+#else
+#error invalid mode
+#endif
+
 	/* Setup the GDT pointer and limit */
 	gp.limit = (sizeof(gdt_entry_t) * GDT_ENTRIES) - 1;
-	gp.base = (unsigned int) &gdt;
+	gp.base = (size_t) &gdt;
 
 	/* Our NULL descriptor */
 	gdt_set_gate(0, 0, 0, 0, 0);
@@ -237,7 +261,7 @@ void gdt_install(void)
 	 */
 	gdt_set_gate(1, 0, 0xFFFFFFFF,
 		GDT_FLAG_RING0 | GDT_FLAG_SEGMENT | GDT_FLAG_CODESEG | GDT_FLAG_PRESENT,
-		GDT_FLAG_4K_GRAN | GDT_FLAG_32_BIT);
+		GDT_FLAG_4K_GRAN | mode);
 
 	/* 
 	 * The third entry is our Data Segment. It's EXACTLY the
@@ -246,33 +270,37 @@ void gdt_install(void)
 	 */
 	gdt_set_gate(2, 0, 0xFFFFFFFF,
 		GDT_FLAG_RING0 | GDT_FLAG_SEGMENT | GDT_FLAG_DATASEG | GDT_FLAG_PRESENT,
-		GDT_FLAG_4K_GRAN | GDT_FLAG_32_BIT);
+		GDT_FLAG_4K_GRAN | mode);
 		
 	/*
 	 * Create code segement for userspace applications (ring 3)
 	 */
 	gdt_set_gate(3, 0, 0xFFFFFFFF,
 		GDT_FLAG_RING3 | GDT_FLAG_SEGMENT | GDT_FLAG_CODESEG | GDT_FLAG_PRESENT,
-		GDT_FLAG_4K_GRAN | GDT_FLAG_32_BIT);
+		GDT_FLAG_4K_GRAN | mode);
 
 	/*
 	 * Create data segement for userspace applications (ring 3)
 	 */
 	gdt_set_gate(4, 0, 0xFFFFFFFF,
                 GDT_FLAG_RING3 | GDT_FLAG_SEGMENT | GDT_FLAG_DATASEG | GDT_FLAG_PRESENT,
-                GDT_FLAG_4K_GRAN | GDT_FLAG_32_BIT);
+                GDT_FLAG_4K_GRAN | mode);
 
 	/*
 	 * Create TSS for each task at ring0 (we use these segments for task switching)
 	 */
 	for(i=0; i<MAX_CORES; i++) {
+#ifdef CONFIG_X86_32
 		/* set default values */
 		task_state_segments[i].eflags = 0x1202;
 		task_state_segments[i].ss0 = 0x10;		// data segment
 		task_state_segments[i].esp0 = 0xDEADBEEF;	// invalid pseudo address
+#elif defined(CONFIG_X86_64)
+		task_state_segments[i].rsp0 = 0xDEADBEEF;       // invalid pseudo address
+#endif
 
 		gdt_set_gate(5+i, (unsigned long) (task_state_segments+i), sizeof(tss_t)-1,
-			GDT_FLAG_PRESENT | GDT_FLAG_TSS | GDT_FLAG_RING0, GDT_FLAG_32_BIT);
+			GDT_FLAG_PRESENT | GDT_FLAG_TSS | GDT_FLAG_RING0, 0);
 	}
 
 	/* Flush out the old GDT and install the new changes! */
diff --git a/arch/x86/kernel/idt.c b/arch/x86/kernel/idt.c
index af7fec6f..c14bfeea 100644
--- a/arch/x86/kernel/idt.c
+++ b/arch/x86/kernel/idt.c
@@ -42,24 +42,6 @@
 static idt_entry_t idt[256] = {[0 ... 255] = {0, 0, 0, 0, 0}};
 static idt_ptr_t idtp;
 
-idt_entry_t configure_idt_entry(size_t base, unsigned short sel,
-		  unsigned char flags)
-{
-	idt_entry_t desc;
-
-	/* The interrupt routine's base address */
-	desc.base_lo = (base & 0xFFFF);
-	desc.base_hi = (base >> 16) & 0xFFFF;
-
-	/* The segment or 'selector' that this IDT entry will use
-	 *  is set here, along with any access flags */
-	desc.sel = sel;
-	desc.always0 = 0;
-	desc.flags = flags;
-
-	return desc;
-}
-
 /*
  * Use this function to set an entry in the IDT. Alot simpler
  * than twiddling with the GDT ;)
@@ -67,7 +49,19 @@ idt_entry_t configure_idt_entry(size_t base, unsigned short sel,
 void idt_set_gate(unsigned char num, size_t base, unsigned short sel,
 		  unsigned char flags)
 {
-	idt[num] = configure_idt_entry(base, sel, flags);
+	/* The interrupt routine's base address */
+	idt[num].base_lo = (base & 0xFFFF);
+	idt[num].base_hi = (base >> 16) & 0xFFFF;
+#ifdef CONFIG_X86_64
+	idt[num].base_hi64 = (base >> 32) & 0xFFFFFFFF;
+	idt[num].reserved = 0x0;
+#endif
+
+	/* The segment or 'selector' that this IDT entry will use
+	 * is set here, along with any access flags */
+	idt[num].sel = sel;
+	idt[num].always0 = 0x0;
+	idt[num].flags = flags;
 }
 
 extern void isrsyscall(void);
@@ -82,7 +76,7 @@ void idt_install(void)
 
 		/* Sets the special IDT pointer up, just like in 'gdt.c' */
 		idtp.limit = (sizeof(idt_entry_t) * 256) - 1;
-		idtp.base = (unsigned int)&idt;
+		idtp.base = (size_t)&idt;
 
 		/* Add any new ISRs to the IDT here using idt_set_gate */
 		idt_set_gate(INT_SYSCALL, (size_t)isrsyscall, KERNEL_CODE_SELECTOR,
diff --git a/arch/x86/kernel/isrs.c b/arch/x86/kernel/isrs.c
index 73f1e203..5d61321a 100644
--- a/arch/x86/kernel/isrs.c
+++ b/arch/x86/kernel/isrs.c
@@ -230,9 +230,14 @@ static void fault_handler(struct state *s)
 {
 	if (s->int_no < 32) {
 		kputs(exception_messages[s->int_no]);
+#ifdef CONFIG_X86_32
 		kprintf(" Exception (%d) at 0x%x:0x%x on core %u, error code 0x%x, eflags 0x%x\n",
 			s->int_no, s->cs, s->eip, CORE_ID, s->error, s->eflags);
-		
+#elif defined(CONFIG_X86_64)
+		kprintf(" Exception (%d) at 0x%llx:0x%llx on core %u, error code 0x%llx, rflags 0x%llx\n",
+			s->int_no, s->cs, s->rip, CORE_ID, s->error, s->rflags);
+#endif
+
 		/* Now, we signalize that we have handled the interrupt */
 		if (apic_is_enabled())
 			apic_eoi();
diff --git a/arch/x86/kernel/string64.asm b/arch/x86/kernel/string64.asm
index f2a25f92..5dc5d855 100644
--- a/arch/x86/kernel/string64.asm
+++ b/arch/x86/kernel/string64.asm
@@ -8,20 +8,11 @@
 ; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 ;
 
-; TODO
-%if 0
-
-[BITS 32]
+[BITS 64]
 SECTION .text
 global strcpy
 strcpy:
-   push ebp
-   mov ebp, esp
-   push edi
-   push esi
-
-   mov esi, [ebp+12]
-   mov edi, [ebp+8]
+   push rdi
 
 L1:
    lodsb
@@ -29,25 +20,16 @@ L1:
    test al, al
    jne L1
    
-   mov eax, [ebp+8]
-   pop esi
-   pop edi
-   pop ebp
+   pop rax
    ret
 
 global strncpy
 strncpy:
-   push ebp
-   mov ebp, esp
-   push edi
-   push esi
-
-   mov ecx, [ebp+16]
-   mov esi, [ebp+12]
-   mov edi, [ebp+8]
+   push rdi
+   mov rcx, rdx
 
 L2:
-   dec ecx
+   dec rcx
    js L3
    lodsb
    stosb
@@ -57,12 +39,10 @@ L2:
    stosb
 
 L3:
-   mov eax, [ebp+8]
-   pop esi
-   pop edi
-   pop ebp
+   pop rax
    ret
 
+%if 0
 ; The following function is derived from JamesM's kernel development tutorials
 ; (http://www.jamesmolloy.co.uk/tutorial_html/)
 global copy_page_physical
diff --git a/arch/x86/mm/page32.c b/arch/x86/mm/page32.c
index 6b8ec587..010dec20 100644
--- a/arch/x86/mm/page32.c
+++ b/arch/x86/mm/page32.c
@@ -78,7 +78,6 @@ inline static size_t copy_page_table(task_t* task, uint32_t pgd_index, page_tabl
 	page_table_t* new_pgt;
 	size_t phyaddr;
 
-#ifdef CONFIG_X86_32
 	if (BUILTIN_EXPECT(!pgt, 0))
 		return 0;
 
@@ -89,7 +88,7 @@ inline static size_t copy_page_table(task_t* task, uint32_t pgd_index, page_tabl
 	if (counter)
 		(*counter)++;
 
-	for(i=0; i<1024; i++) {
+	for(i=0; i<PGT_ENTRIES; i++) {
 		if (pgt->entries[i] & PAGE_MASK) {
 			if (!(pgt->entries[i] & PG_USER)) {
 				// Kernel page => copy only page entries
@@ -114,10 +113,6 @@ inline static size_t copy_page_table(task_t* task, uint32_t pgd_index, page_tabl
 	phyaddr = virt_to_phys((size_t)new_pgt);
 
 	return phyaddr;
-#else
-#warning Currently, not supported
-	return 0;
-#endif
 }
 
 int create_pgd(task_t* task, int copy)
@@ -154,7 +149,7 @@ int create_pgd(task_t* task, int copy)
 
 	spinlock_lock(&kslock);
 
-	for(i=0; i<1024; i++) {
+	for(i=0; i<PGT_ENTRIES; i++) {
 		pgd->entries[i] = boot_pgd.entries[i];
 		// only kernel entries will be copied
 		if (pgd->entries[i] && !(pgd->entries[i] & PG_USER))
@@ -211,7 +206,7 @@ int drop_pgd(void)
 
 	spinlock_lock(&task->pgd_lock);
 	
-	for(i=0; i<1024; i++) {
+	for(i=0; i<PGT_ENTRIES; i++) {
 		if (pgd->entries[i] & PG_USER) {
 			put_page(pgd->entries[i] & PAGE_MASK);
 			pgd->entries[i] = 0;
@@ -310,9 +305,9 @@ size_t map_region(size_t viraddr, size_t phyaddr, uint32_t npages, uint32_t flag
 
 			// set the new page table into the directory
 			if (flags & MAP_USER_SPACE)
-				task->pgd->entries[index] = (size_t)pgt|USER_TABLE;
+				task->pgd->entries[index] = (uint32_t)pgt|USER_TABLE;
 			else
-				task->pgd->entries[index] = (size_t)pgt|KERN_TABLE;
+				task->pgd->entries[index] = (uint32_t)pgt|KERN_TABLE;
 
 			// if paging is already enabled, we need to use the virtual address
 			if (paging_enabled)
@@ -392,7 +387,7 @@ size_t map_region(size_t viraddr, size_t phyaddr, uint32_t npages, uint32_t flag
 int change_page_permissions(size_t start, size_t end, uint32_t flags)
 {
 	uint32_t index1, index2, newflags;
-	size_t viraddr = start & PAGE_MASK;
+	size_t viraddr = start & 0xFFFFF000;
 	size_t phyaddr;
 	page_table_t* pgt;
 	page_dir_t* pgd;
@@ -708,7 +703,7 @@ int arch_paging_init(void)
 
 	// now, we create a self reference
 	per_core(current_task)->pgd->entries[index1] = (((size_t) pgt) & PAGE_MASK)|KERN_TABLE;
-	pgt->entries[index2] = ((size_t) pgt & PAGE_MASK)|KERN_PAGE;
+	pgt->entries[index2] = ((size_t) pgt & 0xFFFFF000)|KERN_PAGE;
 
 	// create the other PGTs for the kernel space
 	for(i=0; i<KERNEL_SPACE/(1024*PAGE_SIZE)-1; i++) {
@@ -783,14 +778,15 @@ int arch_paging_init(void)
 		npages = mb_info->mods_count * sizeof(multiboot_module_t) >> PAGE_SHIFT;
 		if (mb_info->mods_count * sizeof(multiboot_module_t) & (PAGE_SIZE-1))
 			npages++;
-		map_region((size_t) (mb_info->mods_addr), (size_t) (mb_info->mods_addr), npages, MAP_KERNEL_SPACE);
+		map_region((size_t) mb_info->mods_addr & PAGE_MASK, (size_t) mb_info->mods_addr & PAGE_MASK, npages, MAP_KERNEL_SPACE);
 
 		for(i=0; i<mb_info->mods_count; i++, mmodule++) {
 			// map physical address to the same virtual address
 			npages = (mmodule->mod_end - mmodule->mod_start) >> PAGE_SHIFT;
 			if (mmodule->mod_end & (PAGE_SIZE-1))
 				npages++;
-			map_region((size_t) (mmodule->mod_start), (size_t) (mmodule->mod_start), npages, MAP_KERNEL_SPACE);
+			kprintf("Map module %s at 0x%x (%u pages)\n", (char*) mmodule->cmdline, mmodule->mod_start, npages);
+			map_region((size_t) mmodule->mod_start & PAGE_MASK, (size_t) mmodule->mod_start & PAGE_MASK, npages, MAP_KERNEL_SPACE);
 		}
 	}
 #endif
@@ -814,7 +810,7 @@ int arch_paging_init(void)
 #endif
 
 	/* enable paging */
-	write_cr3((size_t) &boot_pgd);
+	write_cr3((uint32_t) &boot_pgd);
 	i = read_cr0();
 	i = i | (1 << 31);
 	write_cr0(i);
diff --git a/arch/x86/mm/page64.c b/arch/x86/mm/page64.c
index 5312b413..9f9ba41b 100644
--- a/arch/x86/mm/page64.c
+++ b/arch/x86/mm/page64.c
@@ -44,9 +44,8 @@
  *
  * 0x00000000 - 0x000FFFFF: reserved for IO devices (16MB)
  * 0x00100000 - 0x0DEADFFF: Kernel (size depends on the configuration) (221MB)
- * 0x0DEAE000 - 0x3FFFEFFF: Kernel heap (801MB)
- * 0x3FFFF000 - 0x3FFFFFFF: Page Tables are mapped in this region (4KB)
- *			   (The last 256 entries belongs to kernel space)
+ * 0x0DEAE000 - 0x3FFFFFFF: Kernel heap 
+ *
  */
 
 /* 
@@ -57,147 +56,24 @@ extern const void kernel_start;
 extern const void kernel_end;
 
 // boot task's page directory and page directory lock
-static page_dir_t boot_pgd = {{[0 ... PGT_ENTRIES-1] = 0}};
+extern page_dir_t boot_pgd;
 static spinlock_t kslock = SPINLOCK_INIT;
-//static int paging_enabled = 0;
+static int paging_enabled = 0;
 
 page_dir_t* get_boot_pgd(void)
 {
 	return &boot_pgd;
 }
 
-#if 0
-/*
- * TODO: We create a full copy of the current task. Copy-On-Access will be the better solution.
- *
- * No PGD locking is needed because onls create_pgd use this function and holds already the
- * PGD lock.
- */
-inline static size_t copy_page_table(task_t* task, uint32_t pgd_index, page_table_t* pgt, int* counter)
-{
-	uint32_t i;
-	page_table_t* new_pgt;
-	size_t phyaddr;
-
-#ifdef CONFIG_X86_32
-	if (BUILTIN_EXPECT(!pgt, 0))
-		return 0;
-
-	new_pgt = kmalloc(sizeof(page_table_t));
-	if (!new_pgt)
-		return 0;
-	memset(new_pgt, 0x00, sizeof(page_table_t));
-	if (counter)
-		(*counter)++;
-
-	for(i=0; i<1024; i++) {
-		if (pgt->entries[i] & PAGE_MASK) {
-			if (!(pgt->entries[i] & PG_USER)) {
-				// Kernel page => copy only page entries
-				new_pgt->entries[i] = pgt->entries[i];
-				continue;
-			}
-
-			phyaddr = get_page();
-			if (!phyaddr)
-				continue;
-			if (counter)
-				(*counter)++;
-
-			copy_page_physical((void*)phyaddr, (void*) (pgt->entries[i] & PAGE_MASK));
-
-			new_pgt->entries[i] = phyaddr | (pgt->entries[i] & 0xFFF); 
-
-			atomic_int32_inc(&task->user_usage);
-		}
-	}
-
-	phyaddr = virt_to_phys((size_t)new_pgt);
-
-	return phyaddr;
-#else
-#warning Currently, not supported
-	return 0;
-#endif
-}
-#endif
-
 int create_pgd(task_t* task, int copy)
 {
-#if 0
-	page_dir_t* pgd;
-	page_table_t* pgt;
-	page_table_t* pgt_container;
-	uint32_t i;
-	uint32_t index1, index2;
-	size_t  viraddr, phyaddr;
-	int counter = 0;
-	task_t* curr_task = per_core(current_task);
+	// Currently, we support only kernel tasks
+	// => all tasks are able to use the same pgd
 
 	if (BUILTIN_EXPECT(!paging_enabled, 0))
 		return -EINVAL;
 
-	// we already know the virtual address of the "page table container"
-	// (see file header)
-	pgt_container = (page_table_t*) ((KERNEL_SPACE - PAGE_SIZE) & PAGE_MASK);
-
-	// create new page directory for the new task
-	pgd = kmalloc(sizeof(page_dir_t));
-	if (!pgd)
-		return -ENOMEM;
-	memset(pgd, 0x00, sizeof(page_dir_t));
-
-	// create a new "page table container" for the new task
-	pgt = kmalloc(sizeof(page_table_t));
-	if (!pgt) {
-		kfree(pgd, sizeof(page_dir_t));
-		return -ENOMEM;
-	}
-	memset(pgt, 0x00, sizeof(page_table_t));
-
-	spinlock_lock(&kslock);
-
-	for(i=0; i<1024; i++) {
-		pgd->entries[i] = boot_pgd.entries[i];
-		// only kernel entries will be copied
-		if (pgd->entries[i] && !(pgd->entries[i] & PG_USER))
-			pgt->entries[i] = pgt_container->entries[i];
-	}
-
-	spinlock_unlock(&kslock);
-
-	// map page table container at the end of the kernel space
-        viraddr = (KERNEL_SPACE - PAGE_SIZE) & PAGE_MASK;
-	index1 = viraddr >> 22;
-	index2 = (viraddr >> 12) & 0x3FF;
-
-	// now, we create a self reference
-	pgd->entries[index1] = ((size_t) virt_to_phys((size_t) pgt) & PAGE_MASK)|KERN_TABLE;
-	pgt->entries[index2] = ((size_t) virt_to_phys((size_t) pgt) & PAGE_MASK)|KERN_PAGE;
-
-	task->pgd = pgd;
-
-	if (copy) {
-		spinlock_lock(&curr_task->pgd_lock);
-
-		for (i=KERNEL_SPACE/(1024*PAGE_SIZE); i<1024; i++) {
-			if (!(curr_task->pgd->entries[i]))
-				continue;
-			if (!(curr_task->pgd->entries[i] & PG_USER))
-				continue;
-
-			phyaddr = copy_page_table(task, i, (page_table_t*) ((KERNEL_SPACE - 1024*PAGE_SIZE + i*PAGE_SIZE) & PAGE_MASK), &counter);
-			if (phyaddr) {
-				pgd->entries[i] = (phyaddr & PAGE_MASK) | (curr_task->pgd->entries[i] & 0xFFF);
-				pgt->entries[i] = (phyaddr & PAGE_MASK) | KERN_PAGE; 
-			}
-		}
-
-		spinlock_unlock(&curr_task->pgd_lock);
-	}
-
-	return counter;
-#endif
+	task->pgd = get_boot_pgd();
 
 	return 0;
 }
@@ -238,9 +114,11 @@ int drop_pgd(void)
 
 size_t virt_to_phys(size_t viraddr)
 {
-#if 0
 	task_t* task = per_core(current_task);
-	uint32_t index1, index2;
+	uint16_t idx_pd4 = (viraddr >> 39) & 0x1FF;
+	uint16_t idx_dirp = (viraddr >> 30) & 0x1FF;
+	uint16_t idx_dir = (viraddr >> 21) & 0x1FF;
+	uint16_t idx_table = (viraddr >> 12) & 0x1FF;
 	page_table_t* pgt;
 	size_t ret = 0;
 
@@ -252,17 +130,24 @@ size_t virt_to_phys(size_t viraddr)
 
 	spinlock_lock(&task->pgd_lock);
 
-	index1 = viraddr >> 22;
-	index2 = (viraddr >> 12) & 0x3FF;
-
-	if (!(task->pgd->entries[index1] & PAGE_MASK))
+	// Currently, we allocate pages only in kernel space.
+	// => physical address of the page table is identical of the virtual address
+	pgt = (page_table_t*) (task->pgd->entries[idx_pd4] & PAGE_MASK);
+	if (!pgt)
 		goto out;
 
-	pgt = (page_table_t*) ((KERNEL_SPACE - 1024*PAGE_SIZE + index1*PAGE_SIZE) & PAGE_MASK);
-	if (!pgt || !(pgt->entries[index2]))
+	pgt = (page_table_t*) (pgt->entries[idx_dirp] & PAGE_MASK);
+	if (!pgt)
+		goto out;
+
+	pgt = (page_table_t*) (pgt->entries[idx_dir] & PAGE_MASK);
+	if (!pgt)
+		goto out;
+
+	ret = (size_t) (pgt->entries[idx_table] & PAGE_MASK);
+	if (!ret)
 		goto out;
 
-	ret = pgt->entries[index2] & PAGE_MASK;	// determine page frame
 	ret = ret | (viraddr & 0xFFF);			// add page offset
 out:
 	//kprintf("vir %p to phy %p\n", viraddr, ret);
@@ -270,18 +155,14 @@ out:
 	spinlock_unlock(&task->pgd_lock);
 
 	return ret;
-#endif
-	return 0;
 }
 
 size_t map_region(size_t viraddr, size_t phyaddr, uint32_t npages, uint32_t flags)
 {
-#if 0
 	task_t* task = per_core(current_task);
 	spinlock_t* pgd_lock;
 	page_table_t* pgt;
-	size_t index, i;
-	size_t ret;
+	size_t i, ret;
 
 	if (BUILTIN_EXPECT(!task || !task->pgd, 0))
 		return 0;
@@ -300,95 +181,64 @@ size_t map_region(size_t viraddr, size_t phyaddr, uint32_t npages, uint32_t flag
 		viraddr = vm_alloc(npages, flags);
 		if (BUILTIN_EXPECT(!viraddr, 0)) {
 			spinlock_unlock(pgd_lock);
-			kputs("map_adress: found no valid virtual address\n");
+			kputs("map_region: found no valid virtual address\n");
 			return 0;
 		}
 	}
 
 	ret = viraddr;
-	//kprintf("map %d pages from %p to %p\n", npages, phyaddr, ret);
 	for(i=0; i<npages; i++, viraddr+=PAGE_SIZE, phyaddr+=PAGE_SIZE) {
-		index = viraddr >> 22;
+		uint16_t idx_pd4 = (viraddr >> 39) & 0x1FF;
+		uint16_t idx_dirp = (viraddr >> 30) & 0x1FF;
+		uint16_t idx_dir = (viraddr >> 21) & 0x1FF;
+		uint16_t idx_table = (viraddr >> 12) & 0x1FF;
 
-		if (!(task->pgd->entries[index])) {
-			page_table_t* pgt_container;
+		pgt = (page_table_t*) (task->pgd->entries[idx_pd4] & PAGE_MASK);
+		if (!pgt) {
+			spinlock_unlock(pgd_lock);
+			kputs("map_region: out of memory\n");
+			return 0;
+		}
+	
+		pgt = (page_table_t*) (pgt->entries[idx_dirp] & PAGE_MASK);
+		if (!pgt) {
+			spinlock_unlock(pgd_lock);
+			kputs("map_region: out of memory\n");
+			return 0;
+		}
 
-			pgt = (page_table_t*) get_pages(1);
-			if (BUILTIN_EXPECT(!pgt, 0)) {
-				spinlock_unlock(pgd_lock);
-				kputs("map_address: out of memory\n");
-				return 0;
-			}
-
-			// set the new page table into the directory
-			if (flags & MAP_USER_SPACE)
-				task->pgd->entries[index] = (size_t)pgt|USER_TABLE;
-			else
-				task->pgd->entries[index] = (size_t)pgt|KERN_TABLE;
-
-			// if paging is already enabled, we need to use the virtual address
-			if (paging_enabled)
-				// we already know the virtual address of the "page table container"
-				// (see file header)
-				pgt_container = (page_table_t*) ((KERNEL_SPACE - PAGE_SIZE) & PAGE_MASK);
-			else
-				pgt_container = (page_table_t*) (task->pgd->entries[(KERNEL_SPACE - PAGE_SIZE) >> 22] & PAGE_MASK);
-
-			if (BUILTIN_EXPECT(!pgt_container, 0)) {
-				spinlock_unlock(pgd_lock);
-				kputs("map_address: internal error\n");
-				return 0;
-			}
-
-			// map the new table into the address space of the kernel space
-		        pgt_container->entries[index] = ((size_t) pgt)|KERN_PAGE;
-
-			// clear the page table
-			if (paging_enabled)
-				memset((void*) ((KERNEL_SPACE - 1024*PAGE_SIZE + index*PAGE_SIZE) & PAGE_MASK), 0x00, PAGE_SIZE);
-			else
-				memset(pgt, 0x00, PAGE_SIZE);
-		} else pgt = (page_table_t*) (task->pgd->entries[index] & PAGE_MASK);
+		pgt = (page_table_t*) (pgt->entries[idx_dir] & PAGE_MASK);
+		if (!pgt) {
+			spinlock_unlock(pgd_lock);
+			kputs("map_region: out of memory\n");
+			return 0;
+		}
 
 		/* convert physical address to virtual */
-		if (paging_enabled)
-			pgt = (page_table_t*) ((KERNEL_SPACE - 1024*PAGE_SIZE + index*PAGE_SIZE) & PAGE_MASK);
+		// Currently, we allocate pages only in kernel space.
+		// => physical address of the page table is identical of the virtual address
+		//if (paging_enabled)
+		//	pgt = (page_table_t*) ((KERNEL_SPACE - 1024*PAGE_SIZE + index*PAGE_SIZE) & PAGE_MASK);
 
-		index = (viraddr >> 12) & 0x3FF;
-		if (pgt->entries[index] && !(flags & MAP_REMAP)) {
+		if (pgt->entries[idx_table] && !(flags & MAP_REMAP)) {
 			spinlock_unlock(pgd_lock);
 			kprintf("0x%x is already mapped\n", viraddr);
 			return 0;
 		}
 
 		if (flags & MAP_USER_SPACE)
-			pgt->entries[index] = USER_PAGE|(phyaddr & PAGE_MASK);
+			pgt->entries[idx_table] = USER_PAGE|(phyaddr & PAGE_MASK);
 		else
-			pgt->entries[index] = KERN_PAGE|(phyaddr & PAGE_MASK);
+			pgt->entries[idx_table] = KERN_PAGE|(phyaddr & PAGE_MASK);
 
 		if (flags & MAP_NO_CACHE)
-			pgt->entries[index] |= PG_PCD;
-#ifdef CONFIG_ROCKCREEK
-		if (flags & MAP_MPE)
-			pgt->entries[index] |= PG_MPE;
-#endif
-		if (flags & MAP_SVM_STRONG)
-#ifndef SVM_WB
-			pgt->entries[index] |= PG_SVM_STRONG|PG_PWT;
-#else
-			pgt->entries[index] |= PG_SVM;
-#endif
-		if (flags & MAP_SVM_LAZYRELEASE)
-			pgt->entries[index] |= PG_SVM_LAZYRELEASE|PG_PWT;
-
-		if (flags & MAP_SVM_INIT)
-			pgt->entries[index] |=  PG_SVM_INIT;
+			pgt->entries[idx_table] |= PG_PCD;
 
 		if (flags & MAP_NO_ACCESS)
-			pgt->entries[index] &= ~PG_PRESENT;
+			pgt->entries[idx_table] &= ~PG_PRESENT;
 
 		if (flags & MAP_WT)
-			pgt->entries[index] |= PG_PWT;
+			pgt->entries[idx_table] |= PG_PWT;
 
 		if (flags & MAP_USER_SPACE)
 			atomic_int32_inc(&task->user_usage);
@@ -399,9 +249,6 @@ size_t map_region(size_t viraddr, size_t phyaddr, uint32_t npages, uint32_t flag
 	spinlock_unlock(pgd_lock);
 
 	return ret;
-#endif
-
-	return 0;
 }
 
 int change_page_permissions(size_t start, size_t end, uint32_t flags)
@@ -469,7 +316,7 @@ int change_page_permissions(size_t start, size_t end, uint32_t flags)
 	spinlock_unlock(&task->pgd_lock);
 #endif
 
-	return 0;
+	return -EINVAL;
 }
 
 /* 
@@ -479,11 +326,9 @@ int change_page_permissions(size_t start, size_t end, uint32_t flags)
  */
 size_t vm_alloc(uint32_t npages, uint32_t flags)
 {
-#if 0
 	task_t* task = per_core(current_task);
 	spinlock_t* pgd_lock;
-	uint32_t index1, index2, j;
-	size_t viraddr, i, ret = 0;
+	size_t viraddr, i, j, ret = 0;
 	size_t start, end;
 	page_table_t* pgt;
 
@@ -508,11 +353,35 @@ size_t vm_alloc(uint32_t npages, uint32_t flags)
 	viraddr = i = start;
 	j = 0;
 	do {
-		index1 = i >> 22;
-		index2 = (i >> 12) & 0x3FF;
+		uint16_t idx_pd4 = (viraddr >> 39) & 0x1FF;
+		uint16_t idx_dirp = (viraddr >> 30) & 0x1FF;
+		uint16_t idx_dir = (viraddr >> 21) & 0x1FF;
+		uint16_t idx_table = (viraddr >> 12) & 0x1FF;
 
-		pgt = (page_table_t*) ((KERNEL_SPACE - 1024*PAGE_SIZE + index1*PAGE_SIZE) & PAGE_MASK);
-		if (!pgt || !(pgt->entries[index2])) {
+		// Currently, we allocate pages only in kernel space.
+		// => physical address of the page table is identical of the virtual address
+		pgt = (page_table_t*) (task->pgd->entries[idx_pd4] & PAGE_MASK);
+		if (!pgt) {
+			i += (size_t)PGT_ENTRIES*PGT_ENTRIES*PGT_ENTRIES*PAGE_SIZE;
+			j += PGT_ENTRIES*PGT_ENTRIES*PGT_ENTRIES;
+			continue;
+		}
+
+		pgt = (page_table_t*) (pgt->entries[idx_dirp] & PAGE_MASK);
+		if (!pgt) {
+			i += PGT_ENTRIES*PGT_ENTRIES*PAGE_SIZE;
+			j += PGT_ENTRIES*PGT_ENTRIES;
+			continue;
+		}
+
+		pgt = (page_table_t*) (pgt->entries[idx_dir] & PAGE_MASK);
+                if (!pgt) {
+                        i += PGT_ENTRIES*PAGE_SIZE;
+                        j += PGT_ENTRIES;
+                        continue;
+                }
+
+		if (!(pgt->entries[idx_table])) {
 			i+=PAGE_SIZE;
 			j++;
 		} else {
@@ -529,21 +398,19 @@ size_t vm_alloc(uint32_t npages, uint32_t flags)
 	spinlock_unlock(pgd_lock);
 
 	return ret;
-#endif
-	return 0;
 }
 
 int unmap_region(size_t viraddr, uint32_t npages)
 {
-#if 0
 	task_t* task = per_core(current_task);
 	spinlock_t* pgd_lock;
-	uint32_t i;
-	uint32_t index1, index2;
 	page_table_t* pgt;
+	size_t i;
+	uint16_t idx_pd4, idx_dirp;
+	uint16_t idx_dir, idx_table;
 
 	if (BUILTIN_EXPECT(!task || !task->pgd || !paging_enabled, 0))
-	return -EINVAL;
+		return -EINVAL;
 
 	if (viraddr <= KERNEL_SPACE)
 		pgd_lock = &kslock;
@@ -552,16 +419,43 @@ int unmap_region(size_t viraddr, uint32_t npages)
 
 	spinlock_lock(pgd_lock);
 
-	for(i=0; i<npages; i++, viraddr+=PAGE_SIZE)
+	i = 0;
+	while(i<npages)
 	{
-		index1 = viraddr >> 22;
-		index2 = (viraddr >> 12) & 0x3FF;
+		idx_pd4 = (viraddr >> 39) & 0x1FF;
+		idx_dirp = (viraddr >> 30) & 0x1FF;
+		idx_dir = (viraddr >> 21) & 0x1FF;
+		idx_table = (viraddr >> 12) & 0x1FF;
 
-		pgt = (page_table_t*) ((KERNEL_SPACE - 1024*PAGE_SIZE + index1*PAGE_SIZE) & PAGE_MASK);
-		if (!pgt)
+		// Currently, we allocate pages only in kernel space.
+		// => physical address of the page table is identical of the virtual address
+		pgt = (page_table_t*) (task->pgd->entries[idx_pd4] & PAGE_MASK);
+		if (!pgt) {
+			viraddr += (size_t) PGT_ENTRIES*PGT_ENTRIES*PGT_ENTRIES*PAGE_SIZE;
+			i += PGT_ENTRIES*PGT_ENTRIES*PGT_ENTRIES;
 			continue;
-		pgt->entries[index2] &= ~PG_PRESENT;
+		}
 
+		pgt = (page_table_t*) (pgt->entries[idx_dirp] & PAGE_MASK);
+		if (!pgt) {
+			viraddr += PGT_ENTRIES*PGT_ENTRIES*PAGE_SIZE;
+			i += PGT_ENTRIES*PGT_ENTRIES;
+			continue;
+		}
+
+		pgt = (page_table_t*) (pgt->entries[idx_dir] & PAGE_MASK);
+		if (!pgt) {
+			viraddr += PGT_ENTRIES*PAGE_SIZE;
+			i += PGT_ENTRIES;
+                        continue;
+                }
+
+		if (pgt->entries[idx_table]) 
+			pgt->entries[idx_table] &= ~PG_PRESENT;
+
+		viraddr +=PAGE_SIZE;
+		i++;
+			
 		if (viraddr > KERNEL_SPACE)
 			atomic_int32_dec(&task->user_usage);
 
@@ -569,19 +463,18 @@ int unmap_region(size_t viraddr, uint32_t npages)
 	}
 
 	spinlock_unlock(pgd_lock);
-#endif
 
 	return 0;
 }
 
 int vm_free(size_t viraddr, uint32_t npages)
 {
-#if 0
 	task_t* task = per_core(current_task);
 	spinlock_t* pgd_lock;
-	uint32_t i;
-	uint32_t index1, index2;
 	page_table_t* pgt;
+	size_t i;
+	uint16_t idx_pd4, idx_dirp;
+	uint16_t idx_dir, idx_table;
 
 	if (BUILTIN_EXPECT(!task || !task->pgd || !paging_enabled, 0))
 		return -EINVAL;
@@ -593,61 +486,47 @@ int vm_free(size_t viraddr, uint32_t npages)
 
 	spinlock_lock(pgd_lock);
 
-	for(i=0; i<npages; i++, viraddr+=PAGE_SIZE)
+	i = 0;
+	while(i<npages)
 	{
-		index1 = viraddr >> 22;
-		index2 = (viraddr >> 12) & 0x3FF;
+		idx_pd4 = (viraddr >> 39) & 0x1FF;
+		idx_dirp = (viraddr >> 30) & 0x1FF;
+		idx_dir = (viraddr >> 21) & 0x1FF;
+		idx_table = (viraddr >> 12) & 0x1FF;
 
-                pgt = (page_table_t*) ((KERNEL_SPACE - 1024*PAGE_SIZE + index1*PAGE_SIZE) & PAGE_MASK);
-		if (!pgt)
+		// Currently, we allocate pages only in kernel space.
+		// => physical address of the page table is identical of the virtual address
+		pgt = (page_table_t*) (task->pgd->entries[idx_pd4] & PAGE_MASK);
+		if (!pgt) {
+			viraddr += (size_t) PGT_ENTRIES*PGT_ENTRIES*PGT_ENTRIES*PAGE_SIZE;
+			i += PGT_ENTRIES*PGT_ENTRIES*PGT_ENTRIES;
 			continue;
-		pgt->entries[index2] = 0;
+		}
+
+		pgt = (page_table_t*) (pgt->entries[idx_dirp] & PAGE_MASK);
+		if (!pgt) {
+			viraddr += PGT_ENTRIES*PGT_ENTRIES*PAGE_SIZE;
+			i += PGT_ENTRIES*PGT_ENTRIES;
+			continue;
+		}
+
+		pgt = (page_table_t*) (pgt->entries[idx_dir] & PAGE_MASK);
+		if (!pgt) {
+			viraddr += PGT_ENTRIES*PAGE_SIZE;
+			i += PGT_ENTRIES;
+			continue;
+		}
+
+		if (pgt->entries[idx_table])
+			pgt->entries[idx_table] = 0;
+
+		viraddr +=PAGE_SIZE;
+		i++;
 
 		tlb_flush_one_page(viraddr);
 	}
 
 	spinlock_unlock(pgd_lock);
-#endif
-
-	return 0;
-}
-
-#if 0
-int print_paging_tree(size_t viraddr)
-{
-	task_t* task = per_core(current_task);
-	uint32_t index1, index2;
-	page_dir_t* pgd = NULL;
-	page_table_t* pgt = NULL;
-
-	if (BUILTIN_EXPECT(!viraddr, 0))
-		return -EINVAL;
-
-	index1 = viraddr >> 22;
-	index2 = (viraddr >> 12) & 0x3FF;
-
-	spinlock_lock(&task->pgd_lock);
-
-	kprintf("Paging dump of address 0x%x\n", viraddr);
-	pgd = task->pgd;
-	kprintf("\tPage directory entry %u: ", index1);
-	if (pgd) {
-		kprintf("0x%0x\n", pgd->entries[index1]);
-		pgt = (page_table_t*) (pgd->entries[index1] & PAGE_MASK);
-	} else
-		kputs("invalid page directory\n");
-
-	/* convert physical address to virtual */
-	if (paging_enabled && pgt)
-		pgt = (page_table_t*) (KERNEL_SPACE - 1024*PAGE_SIZE + index1*PAGE_SIZE);
-
-	kprintf("\tPage table entry %u: ", index2);
-	if (pgt)
-		kprintf("0x%x\n", pgt->entries[index2]);
-	else 
-		kputs("invalid page table\n");
-
-	spinlock_unlock(&task->pgd_lock);
 
 	return 0;
 }
@@ -655,14 +534,12 @@ int print_paging_tree(size_t viraddr)
 static void pagefault_handler(struct state *s)
 {
 	task_t* task = per_core(current_task);
-	page_dir_t* pgd = task->pgd;
-	page_table_t* pgt = NULL;
+	//page_dir_t* pgd = task->pgd;
+	//page_table_t* pgt = NULL;
 	size_t viraddr = read_cr2();
-	size_t phyaddr;
-#ifdef CONFIG_ROCKCREEK
-	uint32_t index1, index2;
-#endif
+	//size_t phyaddr;
 
+#if 0
 	if ((viraddr >= task->start_heap) && (viraddr <= task->end_heap) && (viraddr > KERNEL_SPACE)) {
 		viraddr = viraddr & PAGE_MASK;
 
@@ -678,87 +555,28 @@ static void pagefault_handler(struct state *s)
 		kprintf("Could not map 0x%x at 0x%x\n", phyaddr, viraddr);
 		put_page(phyaddr);
 	}
-
-#ifdef CONFIG_ROCKCREEK
-	// does our SVM system need to handle this page fault?
-	index1 = viraddr >> 22;
-	index2 = (viraddr >> 12) & 0x3FF;
-	if (!pgd || !(pgd->entries[index1] & PAGE_MASK))
-                goto default_handler;
-        pgt = (page_table_t*) ((KERNEL_SPACE - 1024*PAGE_SIZE + index1*PAGE_SIZE) & PAGE_MASK);
-	if (!pgt || !(pgt->entries[index2]))
-		goto default_handler;
-	if (pgt->entries[index2] & PG_SVM_INIT) {
-		if (BUILTIN_EXPECT(!svm_alloc_page(viraddr, pgt), 1))
-			return;
-		else
-			goto default_handler;
-	}
-	if (pgt->entries[index2] & PG_SVM_STRONG)
-		if (BUILTIN_EXPECT(!svm_access_request(viraddr), 1))
-			return;
 #endif
 
 default_handler:
-	kprintf("PAGE FAULT: Task %u got page fault at %p (irq %d, cs:eip 0x%x:0x%x)\n", task->id, viraddr, s->int_no, s->cs, s->eip);
-	kprintf("Register state: eax = 0x%x, ebx = 0x%x, ecx = 0x%x, edx = 0x%x, edi = 0x%x, esi = 0x%x, ebp = 0x%x, esp = 0x%x\n", 
-		s->eax, s->ebx, s->ecx, s->edx, s->edi, s->esi, s->ebp, s->esp);
+	kprintf("PAGE FAULT: Task %u got page fault at %p (irq %llu, cs:rip 0x%llx:0x%llx)\n", task->id, viraddr, s->int_no, s->cs, s->rip);
+	kprintf("Register state: rax = 0x%llx, rbx = 0x%llx, rcx = 0x%llx, rdx = 0x%llx, rdi = 0x%llx, rsi = 0x%llx, rbp = 0x%llx, rsp = 0x%llx\n", 
+		s->rax, s->rbx, s->rcx, s->rdx, s->rdi, s->rsi, s->rbp, s->rsp);
 
+while(1);
 	irq_enable();
 	abort();
 }
-#endif
 
 int arch_paging_init(void)
 {
-#if 0
-	uint32_t i, npages, index1, index2;
-	page_table_t* pgt;
-	size_t viraddr;
+	uint32_t i, npages;
 
 	// uninstall default handler and install our own
 	irq_uninstall_handler(14);
 	irq_install_handler(14, pagefault_handler);
 
-	// Create a page table to reference to the other page tables
-	pgt = (page_table_t*) get_page();
-	if (!pgt) {
-		kputs("arch_paging_init: Not enough memory!\n");
-		return -ENOMEM;
-	}
-	memset(pgt, 0, PAGE_SIZE);
-
-	// map this table at the end of the kernel space
-	viraddr = KERNEL_SPACE - PAGE_SIZE;
-	index1 = viraddr >> 22;
-	index2 = (viraddr >> 12) & 0x3FF;
-
-	// now, we create a self reference
-	per_core(current_task)->pgd->entries[index1] = (((size_t) pgt) & PAGE_MASK)|KERN_TABLE;
-	pgt->entries[index2] = ((size_t) pgt & PAGE_MASK)|KERN_PAGE;
-
-	// create the other PGTs for the kernel space
-	for(i=0; i<KERNEL_SPACE/(1024*PAGE_SIZE)-1; i++) {
-		size_t phyaddr = get_page();
-
-		if (!phyaddr) {
-			kputs("arch_paging_init: Not enough memory!\n");
-			return -ENOMEM;
-		}
-
-		memset((void*) phyaddr, 0, PAGE_SIZE);
-		per_core(current_task)->pgd->entries[i] = (phyaddr & PAGE_MASK)|KERN_TABLE;
-		pgt->entries[i] = (phyaddr & PAGE_MASK)|KERN_PAGE;
-	}
-
-	/* 
-	 * Set the page table and page directory entries for the kernel. We map the kernel's physical address 
-	 * to the same virtual address.
-	 */
-	npages = ((size_t) &kernel_end - (size_t) &kernel_start) >> PAGE_SHIFT;
-	if ((size_t)&kernel_end & (PAGE_SIZE-1))
-		npages++;
-	map_region((size_t)&kernel_start, (size_t)&kernel_start, npages, MAP_KERNEL_SPACE);
+	// kernel is already maped into the kernel space (see entry64.asm)
+	// this includes .data, .bss, .text, video memory and the multiboot structure
 
 #if MAX_CORES > 1
 	// Reserve page for smp boot code
@@ -768,18 +586,7 @@ int arch_paging_init(void)
 	}
 #endif
 
-#ifdef CONFIG_VGA
-	// map the video memory into the kernel space
-	map_region(VIDEO_MEM_ADDR, VIDEO_MEM_ADDR, 1, MAP_KERNEL_SPACE|MAP_NO_CACHE);
-#endif
-
 #ifdef CONFIG_MULTIBOOT
-	/*
-	 * of course, mb_info has to map into the kernel space
-	 */
-	if (mb_info)
-		map_region((size_t) mb_info & PAGE_MASK, (size_t) mb_info & PAGE_MASK, 1, MAP_KERNEL_SPACE);
-
 #if 0
 	/*
 	 * Map reserved memory regions into the kernel space
@@ -817,46 +624,15 @@ int arch_paging_init(void)
 			npages = (mmodule->mod_end - mmodule->mod_start) >> PAGE_SHIFT;
 			if (mmodule->mod_end & (PAGE_SIZE-1))
 				npages++;
+			//kprintf("Map module %s at 0x%x (%u pages)\n", (char*) mmodule->cmdline, mmodule->mod_start, npages);
 			map_region((size_t) (mmodule->mod_start), (size_t) (mmodule->mod_start), npages, MAP_KERNEL_SPACE);
 		}
 	}
 #endif
 
-#ifdef CONFIG_ROCKCREEK
-	// map SCC's bootinfo
-	viraddr = map_region(SCC_BOOTINFO, SCC_BOOTINFO, 1, MAP_KERNEL_SPACE);
-	kprintf("Map SCC's bootinfos at 0x%x\n", viraddr);
-
-	// map SCC's configuration registers
-	viraddr = map_region(CRB_X0_Y0, CRB_X0_Y0, (CRB_OWN-CRB_X0_Y0+16*1024*1024) >> PAGE_SHIFT, MAP_KERNEL_SPACE|MAP_NO_CACHE);
-	kprintf("Map configuration registers at 0x%x\n", viraddr);
-
-	// map SCC's message passing buffers
-	viraddr = map_region(MPB_X0_Y0, MPB_X0_Y0, (MPB_OWN-MPB_X0_Y0+16*1024*1024) >> PAGE_SHIFT, MAP_KERNEL_SPACE|MAP_MPE);
-	kprintf("Map message passing buffers at 0x%x\n", viraddr);
-
-	// map the FPGA registers
-	viraddr = map_region(FPGA_BASE, FPGA_BASE, 0x10000 >> PAGE_SHIFT, MAP_KERNEL_SPACE|MAP_NO_CACHE);
-	kprintf("Map FPGA regsiters at 0x%x\n", viraddr);
-#endif
-
-	/* enable paging */
-	write_cr3((size_t) &boot_pgd);
-	i = read_cr0();
-	i = i | (1 << 31);
-	write_cr0(i);
+	/* signalize that we are able to use paging */
 	paging_enabled = 1;
 
-#ifdef CONFIG_ROCKCREEK
-	// map the initial ramdisk
-	npages = bootinfo->size >> PAGE_SHIFT;
-	if (bootinfo->size & (PAGE_SIZE-1))
-		npages++;
-	viraddr = map_region(0, bootinfo->addr, npages, MAP_KERNEL_SPACE);
-	kprintf("Map initrd from 0x%x to 0x%x (size %u bytes)\n", bootinfo->addr, viraddr, bootinfo->size);
-	bootinfo->addr = viraddr;
-#endif
-
 	/*
 	 * we turned on paging
 	 * => now, we are able to register our task for Task State Switching
@@ -865,7 +641,6 @@ int arch_paging_init(void)
 
 	// APIC registers into the kernel address space
 	map_apic();
-#endif
 
 	return 0;
 }
diff --git a/fs/initrd.c b/fs/initrd.c
index 3ecfa20c..fd889269 100644
--- a/fs/initrd.c
+++ b/fs/initrd.c
@@ -456,8 +456,8 @@ int initrd_init(void)
 		initrd_file_desc_t* file_desc;
 		vfs_node_t* new_node;
 
-		if (header->magic != INITRD_MAGIC_NUMBER) {
-			kprintf("Invalid magic number for a init ram disk\n");
+		if (BUILTIN_EXPECT(header->magic != INITRD_MAGIC_NUMBER, 0)) {
+			kprintf("Invalid magic number for a init ram disk: 0x%x\n", header->magic);
 			continue;
 		}
 
diff --git a/kernel/main.c b/kernel/main.c
index f1017ef1..62753e41 100644
--- a/kernel/main.c
+++ b/kernel/main.c
@@ -62,17 +62,12 @@ int main(void)
 {
 	tid_t id;
 
-
-vga_init();
-vga_puts("aaa");
-	//lowlevel_init();
+	lowlevel_init();
 
 	pushbg(COL_BLUE);
 	kprintf("This is MetalSVM %s Build %u, %u\n", 
 			METALSVM_VERSION, &__BUILD_DATE, &__BUILD_TIME);
 	popbg();
-
-while(1);
 	system_init();
 	irq_init();
 	timer_init();
diff --git a/kernel/tasks.c b/kernel/tasks.c
index d283e55d..866a4a43 100644
--- a/kernel/tasks.c
+++ b/kernel/tasks.c
@@ -719,7 +719,6 @@ invalid:
 
 	return -EINVAL;
 #else
-#warning Currently, not supported!
 	return -EINVAL;
 #endif
 }
@@ -786,7 +785,6 @@ int create_user_task(tid_t* id, const char* fname, char** argv)
 		while ((*dest++ = *src++) != 0);
 	}
 
-
 	/* create new task */
 	return create_task(id, user_entry, load_args, NORMAL_PRIO);
 }
diff --git a/link32.ld b/link32.ld
index ad03b8f5..af270aa6 100644
--- a/link32.ld
+++ b/link32.ld
@@ -20,8 +20,8 @@ SECTIONS
   .data ALIGN(4096) : AT(ADDR(.data)) {
     *(.data)
   }
-  bss_start = .;
   .bss ALIGN(4096) : AT(ADDR(.bss)) {
+    bss_start = .;
     *(.bss)
   }
   bss_end = .;
diff --git a/link64.ld b/link64.ld
index 2794f82c..b2cb05d8 100644
--- a/link64.ld
+++ b/link64.ld
@@ -20,8 +20,8 @@ SECTIONS
   .data ALIGN(4096) : AT(ADDR(.data)) {
     *(.data)
   }
-  bss_start = .;
   .bss ALIGN(4096) : AT(ADDR(.bss)) {
+    bss_start = .;
     *(.bss)
   }
   bss_end = .;
diff --git a/mm/memory.c b/mm/memory.c
index eed59d5d..1c7c89a2 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -96,7 +96,7 @@ int mmu_init(void)
 	size_t kernel_size;
 	unsigned int i; 
 	size_t addr;
-	int ret;
+	int ret = 0;
 
 	// at first, set default value of the bitmap
 	memset(bitmap, 0xFF, sizeof(uint8_t)*BITMAP_SIZE);
@@ -128,35 +128,6 @@ int mmu_init(void)
 			HALT;
 		}
 	}
-
-	/* 
-	 * Modules like the init ram disk are already loaded.
-	 * Therefore, we set these pages as used.
-	 */
-	if (mb_info && (mb_info->flags & MULTIBOOT_INFO_MODS)) {
-		multiboot_module_t* mmodule = (multiboot_module_t*) ((size_t) mb_info->mods_addr);
-
-		/*
-		 * Mark the mb_info as used.
- 		 */
-		page_set_mark((size_t)mb_info >> PAGE_SHIFT);
-		atomic_int32_inc(&total_allocated_pages);
-		atomic_int32_dec(&total_available_pages);
-
-		for(addr = mb_info->mods_addr; addr < mb_info->mods_addr + mb_info->mods_count * sizeof(multiboot_module_t); addr += PAGE_SIZE) {
-			page_set_mark(addr >> PAGE_SHIFT);
-			atomic_int32_inc(&total_allocated_pages);
-			atomic_int32_dec(&total_available_pages);
-		}
-
-		for(i=0; i<mb_info->mods_count; i++, mmodule++) {
-			for(addr=mmodule->mod_start; addr<mmodule->mod_end; addr+=PAGE_SIZE) {
-				page_set_mark(addr >> PAGE_SHIFT);
-				atomic_int32_inc(&total_allocated_pages);
-				atomic_int32_dec(&total_available_pages);
-			}
-		}
-	} 
 #elif defined(CONFIG_ROCKCREEK)
 	/* of course, the first slots belong to the private memory */
 	for(addr=0x00; addr<1*0x1000000; addr+=PAGE_SIZE) {
@@ -210,8 +181,39 @@ int mmu_init(void)
 	atomic_int32_sub(&total_available_pages, 1);
 #endif
 	ret = paging_init();
+	if (ret)
+		return ret;
 
-#ifdef CONFIG_ROCKCREEK
+#ifdef CONFIG_MULTIBOOT
+	/* 
+	 * Modules like the init ram disk are already loaded.
+	 * Therefore, we set these pages as used.
+	 */
+	if (mb_info && (mb_info->flags & MULTIBOOT_INFO_MODS)) {
+		multiboot_module_t* mmodule = (multiboot_module_t*) ((size_t) mb_info->mods_addr);
+
+		/*
+		 * Mark the mb_info as used.
+		 */
+		page_set_mark((size_t)mb_info >> PAGE_SHIFT);
+		atomic_int32_inc(&total_allocated_pages);
+		atomic_int32_dec(&total_available_pages);
+
+		for(addr = mb_info->mods_addr; addr < mb_info->mods_addr + mb_info->mods_count * sizeof(multiboot_module_t); addr += PAGE_SIZE) {
+			page_set_mark(addr >> PAGE_SHIFT);
+			atomic_int32_inc(&total_allocated_pages);
+			atomic_int32_dec(&total_available_pages);
+		}
+
+		for(i=0; i<mb_info->mods_count; i++, mmodule++) {
+			for(addr=mmodule->mod_start; addr<mmodule->mod_end; addr+=PAGE_SIZE) {
+				page_set_mark(addr >> PAGE_SHIFT);
+				atomic_int32_inc(&total_allocated_pages);
+				atomic_int32_dec(&total_available_pages);
+			}
+		}
+	}
+#elif defined(CONFIG_ROCKCREEK)
 	/*
 	 * Now, we are able to read the FPGA registers and to
 	 * determine the number of slots for private memory.