diff --git a/src/arch/x86_64/boot/boot.asm b/src/arch/x86_64/boot/boot.asm
index ebd1d5c..01cafc4 100644
--- a/src/arch/x86_64/boot/boot.asm
+++ b/src/arch/x86_64/boot/boot.asm
@@ -128,15 +128,15 @@ enable_paging:
     or eax, 1 << 5
     mov cr4, eax
 
-    ; set the long mode bit in the EFER MSR (model specific register)
+    ; set the long mode bit & no execute bit in the EFER MSR (model specific register)
     mov ecx, 0xC0000080
     rdmsr
-    or eax, 1 << 8
+    or eax, 1 << 8 | 1 << 11
     wrmsr
 
-    ; enable paging in the cr0 register
+    ; enable paging & write protect in the cr0 register
     mov eax, cr0
-    or eax, 1 << 31
+    or eax, 1 << 31 | 1 << 16
     mov cr0, eax
 
     ret
diff --git a/src/arch/x86_64/boot/entryother.asm b/src/arch/x86_64/boot/entryother.asm
index 9604de0..b8fc568 100644
--- a/src/arch/x86_64/boot/entryother.asm
+++ b/src/arch/x86_64/boot/entryother.asm
@@ -85,15 +85,15 @@ enable_paging:
     or      eax, 1 << 5
     mov     cr4, eax
 
-    ; set the long mode bit in the EFER MSR (model specific register)
+    ; set the long mode bit & no execute bit in the EFER MSR (model specific register)
     mov     ecx, 0xC0000080
     rdmsr
-    or      eax, 1 << 8
+    or      eax, 1 << 8 | 1 << 11
     wrmsr
 
-    ; enable paging in the cr0 register
+    ; enable paging & write protect in the cr0 register
     mov     eax, cr0
-    or      eax, 1 << 31
+    or      eax, 1 << 31 | 1 << 16
     mov     cr0, eax
 
     ret
diff --git a/src/arch/x86_64/cpu.rs b/src/arch/x86_64/cpu.rs
index a29a1af..8e93cca 100644
--- a/src/arch/x86_64/cpu.rs
+++ b/src/arch/x86_64/cpu.rs
@@ -1,20 +1,3 @@
-pub fn init() {
-    enable_nxe_bit();
-    enable_write_protect_bit();
-}
-
-/// Enable 'No-Execute' bit in page entry
-pub fn enable_nxe_bit() {
-    use x86_64::registers::model_specific::*;
-    unsafe { Efer::update(|flags| flags.insert(EferFlags::NO_EXECUTE_ENABLE)); }
-}
-
-/// Enable write protection in kernel mode
-pub fn enable_write_protect_bit() {
-    use x86_64::registers::control::*;
-    unsafe { Cr0::update(|flags| flags.insert(Cr0Flags::WRITE_PROTECT)); }
-}
-
 /// Exit qemu
 /// See: https://wiki.osdev.org/Shutdown
 /// Must run qemu with `-device isa-debug-exit`
diff --git a/src/lib.rs b/src/lib.rs
index e37e010..bacf020 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -64,7 +64,6 @@ mod arch;
 /// The entry point of Rust kernel
 #[no_mangle]
 pub extern "C" fn rust_main(multiboot_information_address: usize) -> ! {
-    arch::cpu::init();
     arch::idt::init();
     io::init();
 
@@ -88,8 +87,7 @@ pub extern "C" fn rust_main(multiboot_information_address: usize) -> ! {
         kernel_memory.push(MemoryArea::new_identity(addr, addr + count * 0x1000, MemoryAttr::default(), "acpi"))
     });
 
-    // FIXME: page fault in SMP
-//    arch::smp::start_other_cores(&acpi, &mut kernel_memory);
+    arch::smp::start_other_cores(&acpi, &mut kernel_memory);
     process::init(kernel_memory);
 
     fs::load_sfs();
@@ -123,7 +121,6 @@ pub extern "C" fn rust_main(multiboot_information_address: usize) -> ! {
 /// The entry point for another processors
 #[no_mangle]
 pub extern "C" fn other_main() -> ! {
-    arch::cpu::init();
     arch::gdt::init();
     arch::idt::init();
     arch::driver::apic::other_init();