diff --git a/crate/aarch64/Cargo.lock b/crate/aarch64/Cargo.lock
new file mode 100644
index 0000000..1038287
--- /dev/null
+++ b/crate/aarch64/Cargo.lock
@@ -0,0 +1,108 @@
+[[package]]
+name = "aarch64"
+version = "0.1.0"
+dependencies = [
+ "bare-metal 0.2.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "bit_field 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "os_bootinfo 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "register 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "usize_conversions 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "ux 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "bare-metal"
+version = "0.2.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "rustc_version 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "bit_field"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "bitflags"
+version = "1.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "cfg-if"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "log"
+version = "0.4.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "cfg-if 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "os_bootinfo"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "register"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "tock-registers 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "rustc_version"
+version = "0.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "semver 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "semver"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "semver-parser 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "semver-parser"
+version = "0.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "tock-registers"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "usize_conversions"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "ux"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[metadata]
+"checksum bare-metal 0.2.4 (registry+https://github.com/rust-lang/crates.io-index)" = "a3caf393d93b2d453e80638d0674597020cef3382ada454faacd43d1a55a735a"
+"checksum bit_field 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ed8765909f9009617974ab6b7d332625b320b33c326b1e9321382ef1999b5d56"
+"checksum bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)" = "228047a76f468627ca71776ecdebd732a3423081fcf5125585bcd7c49886ce12"
+"checksum cfg-if 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)" = "082bb9b28e00d3c9d39cc03e64ce4cea0f1bb9b3fde493f0cbc008472d22bdf4"
+"checksum log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)" = "c84ec4b527950aa83a329754b01dbe3f58361d1c5efacd1f6d68c494d08a17c6"
+"checksum os_bootinfo 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "66481dbeb5e773e7bd85b63cd6042c30786f834338288c5ec4f3742673db360a"
+"checksum register 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "e10f31b6d2299e5620986ad9fcdd66463e125ad72af4f403f9aedf7592d5ccdb"
+"checksum rustc_version 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)" = "138e3e0acb6c9fb258b19b67cb8abd63c00679d2851805ea151465464fe9030a"
+"checksum semver 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "1d7eb9ef2c18661902cc47e535f9bc51b78acd254da71d375c2f6720d9a40403"
+"checksum semver-parser 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)" = "388a1df253eca08550bef6c72392cfe7c30914bf41df5269b68cbd6ff8f570a3"
+"checksum tock-registers 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "3a385d94f3f62e60445a0adb9ff8d9621faa272234530d4c0f848ec98f88e316"
+"checksum usize_conversions 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "f70329e2cbe45d6c97a5112daad40c34cd9a4e18edb5a2a18fefeb584d8d25e5"
+"checksum ux 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "53d8df5dd8d07fedccd202de1887d94481fadaea3db70479f459e8163a1fab41"
diff --git a/crate/aarch64/src/asm.rs b/crate/aarch64/src/asm.rs
index 1c1ee6d..4cd37d7 100644
--- a/crate/aarch64/src/asm.rs
+++ b/crate/aarch64/src/asm.rs
@@ -1,31 +1,9 @@
+//! Miscellaneous assembly instructions and functions
+
 use paging::PhysFrame;
 use addr::{PhysAddr, VirtAddr};
 use regs::*;
 
-#[inline(always)]
-pub fn tlb_invalidate_all() {
-    unsafe {
-        asm!(
-            "dsb ishst
-             tlbi vmalle1is
-             dsb ish
-             isb"
-        );
-    }
-}
-
-#[inline(always)]
-pub fn tlb_invalidate(vaddr: VirtAddr) {
-    unsafe {
-        asm!(
-            "dsb ishst
-             tlbi vaae1is, $0
-             dsb ish
-             isb" :: "r"(vaddr.as_u64() >> 12)
-        );
-    }
-}
-
 /// Returns the current stack pointer.
 #[inline(always)]
 pub fn sp() -> *const u8 {
@@ -37,91 +15,32 @@ pub fn sp() -> *const u8 {
     ptr as *const u8
 }
 
+/// Returns the current point counter.
 #[inline(always)]
 pub unsafe fn get_pc() -> usize {
     let pc: usize;
-    asm!("ADR $0, ." : "=r"(pc));
+    asm!("adr $0, ." : "=r"(pc));
     pc
 }
 
-/// Returns the current exception level.
-///
-/// # Safety
-/// This function should only be called when EL is >= 1.
-#[inline(always)]
-pub unsafe fn current_el() -> u8 {
-    let el_reg: u64;
-    asm!("mrs $0, CurrentEL" : "=r"(el_reg));
-    ((el_reg & 0b1100) >> 2) as u8
-}
-
-#[inline(always)]
-pub unsafe fn get_far() -> usize {
-    let far: usize;
-    asm!("mrs $0, far_el1" : "=r"(far));
-    far
-}
-
-#[inline(always)]
-pub unsafe fn get_ttbr0() -> usize {
-    let ttbr0: usize;
-    asm!("mrs $0, ttbr0_el1" : "=r"(ttbr0));
-    ttbr0
-}
-
-#[inline(always)]
-pub unsafe fn get_ttbr1() -> usize {
-    let ttbr0: usize;
-    asm!("mrs $0, ttbr1_el1" : "=r"(ttbr0));
-    ttbr0
-}
-
-#[inline(always)]
-pub fn address_translate(vaddr: usize) -> usize {
-    let paddr: usize;
-    unsafe {
-        asm!("at S1E1R, $1; mrs $0, par_el1" : "=r"(paddr) : "r"(vaddr));
-    }
-    paddr
-}
-
-/// Returns the SPSel value.
-#[inline(always)]
-pub fn sp_sel() -> u8 {
-    let ptr: u32;
-    unsafe {
-        asm!("mrs $0, SPSel" : "=r"(ptr));
-    }
-
-    (ptr & 1) as u8
-}
-
-/// Returns the core currently executing.
-///
-/// # Safety
-///
-/// This function should only be called when EL is >= 1.
-pub unsafe fn affinity() -> usize {
-    let x: usize;
-    asm!("mrs     $0, mpidr_el1
-          and     $0, $0, #3"
-          : "=r"(x));
-
-    x
-}
+/// The classic no-op
+#[inline]
+pub fn nop() {
+    match () {
+        #[cfg(target_arch = "aarch64")]
+        () => unsafe { asm!("nop" :::: "volatile") },
 
-pub fn wfi() {
-    unsafe {
-        asm!("wfi" :::: "volatile");
+        #[cfg(not(target_arch = "aarch64"))]
+        () => unimplemented!(),
     }
 }
 
-/// The classic no-op
+/// Wait For Interrupt
 #[inline]
-pub fn nop() {
+pub fn wfi() {
     match () {
         #[cfg(target_arch = "aarch64")]
-        () => unsafe { asm!("nop" :::: "volatile") },
+        () => unsafe { asm!("wfi" :::: "volatile") },
 
         #[cfg(not(target_arch = "aarch64"))]
         () => unimplemented!(),
@@ -160,7 +79,44 @@ pub fn eret() -> ! {
     }
 }
 
-pub fn ttbr_el1_read(which: u8) -> (PhysFrame) {
+/// Invalidate all TLB entries.
+#[inline(always)]
+pub fn tlb_invalidate_all() {
+    unsafe {
+        asm!(
+            "dsb ishst
+             tlbi vmalle1is
+             dsb ish
+             isb"
+        );
+    }
+}
+
+/// Invalidate TLB entries that would be used to translate the specified address.
+#[inline(always)]
+pub fn tlb_invalidate(vaddr: VirtAddr) {
+    unsafe {
+        asm!(
+            "dsb ishst
+             tlbi vaae1is, $0
+             dsb ish
+             isb" :: "r"(vaddr.as_u64() >> 12)
+        );
+    }
+}
+
+/// Address Translate.
+#[inline(always)]
+pub fn address_translate(vaddr: usize) -> usize {
+    let paddr: usize;
+    unsafe {
+        asm!("at S1E1R, $1; mrs $0, par_el1" : "=r"(paddr) : "r"(vaddr));
+    }
+    paddr
+}
+
+/// Read TTBRx_EL1 as PhysFrame
+pub fn ttbr_el1_read(which: u8) -> PhysFrame {
     let baddr = match which {
         0 => TTBR0_EL1.get_baddr(),
         1 => TTBR1_EL1.get_baddr(),
@@ -169,6 +125,7 @@ pub fn ttbr_el1_read(which: u8) -> (PhysFrame) {
     PhysFrame::containing_address(PhysAddr::new(baddr))
 }
 
+/// Write TTBRx_EL1 from PhysFrame
 pub fn ttbr_el1_write(which: u8, frame: PhysFrame) {
     let baddr = frame.start_address().as_u64();
     match which {
@@ -178,6 +135,7 @@ pub fn ttbr_el1_write(which: u8, frame: PhysFrame) {
     };
 }
 
+/// write TTBRx_EL1 from PhysFrame and ASID
 pub fn ttbr_el1_write_asid(which: u8, asid: u16, frame: PhysFrame) {
     let baddr = frame.start_address().as_u64();
     match which {
diff --git a/kernel/Cargo.lock b/kernel/Cargo.lock
index 7795f1f..4e2b6dc 100644
--- a/kernel/Cargo.lock
+++ b/kernel/Cargo.lock
@@ -5,7 +5,6 @@ dependencies = [
  "bare-metal 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "bit_field 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
- "log 0.4.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "os_bootinfo 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "register 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "usize_conversions 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -177,14 +176,6 @@ name = "redox_syscall"
 version = "0.1.40"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
-[[package]]
-name = "register"
-version = "0.1.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "tock-registers 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
 [[package]]
 name = "register"
 version = "0.2.1"
@@ -247,11 +238,6 @@ dependencies = [
  "remove_dir_all 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
-[[package]]
-name = "tock-registers"
-version = "0.1.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
 [[package]]
 name = "tock-registers"
 version = "0.2.0"
@@ -279,13 +265,11 @@ dependencies = [
  "bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "bootloader 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "cc 1.0.25 (registry+https://github.com/rust-lang/crates.io-index)",
- "cortex-a 2.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazy_static 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "linked_list_allocator 0.6.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "once 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "redox_syscall 0.1.40 (registry+https://github.com/rust-lang/crates.io-index)",
- "register 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "riscv 0.3.0",
  "simple-filesystem 0.0.1 (git+https://github.com/wangrunji0408/SimpleFileSystem-Rust)",
  "spin 0.4.9 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -399,7 +383,6 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum pulldown-cmark 0.0.3 (registry+https://github.com/rust-lang/crates.io-index)" = "8361e81576d2e02643b04950e487ec172b687180da65c731c03cf336784e6c07"
 "checksum rand 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)" = "8356f47b32624fef5b3301c1be97e5944ecdd595409cc5da11d05f211db6cfbd"
 "checksum redox_syscall 0.1.40 (registry+https://github.com/rust-lang/crates.io-index)" = "c214e91d3ecf43e9a4e41e578973adeb14b474f2bee858742d127af75a0112b1"
-"checksum register 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "0e985243ba7e1c336b62444ef2a10d7bd87cf41a222285ae3de605c859006479"
 "checksum register 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "e10f31b6d2299e5620986ad9fcdd66463e125ad72af4f403f9aedf7592d5ccdb"
 "checksum remove_dir_all 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)" = "3488ba1b9a2084d38645c4c08276a1752dcbf2c7130d74f1569681ad5d2799c5"
 "checksum simple-filesystem 0.0.1 (git+https://github.com/wangrunji0408/SimpleFileSystem-Rust)" = "<none>"
@@ -407,7 +390,6 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum spin 0.4.9 (registry+https://github.com/rust-lang/crates.io-index)" = "37b5646825922b96b5d7d676b5bb3458a54498e96ed7b0ce09dc43a07038fea4"
 "checksum static_assertions 0.2.5 (registry+https://github.com/rust-lang/crates.io-index)" = "c19be23126415861cb3a23e501d34a708f7f9b2183c5252d690941c2e69199d5"
 "checksum tempdir 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)" = "15f2b5fb00ccdf689e0149d1b1b3c03fead81c2b37735d812fa8bddbbf41b6d8"
-"checksum tock-registers 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "2acc33f980e23cee18d234a32d0637fbc1ea55e13ab04012fa857b899fa1b7a9"
 "checksum tock-registers 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "3a385d94f3f62e60445a0adb9ff8d9621faa272234530d4c0f848ec98f88e316"
 "checksum uart_16550 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "269f953d8de3226f7c065c589c7b4a3e83d10a419c7c3b5e2e0f197e6acc966e"
 "checksum unicode-width 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "882386231c45df4700b275c7ff55b6f3698780a650026380e72dabe76fa46526"
diff --git a/kernel/Cargo.toml b/kernel/Cargo.toml
index 06ea088..20b696f 100644
--- a/kernel/Cargo.toml
+++ b/kernel/Cargo.toml
@@ -32,7 +32,6 @@ bit-allocator = { path = "../crate/bit-allocator" }
 ucore-memory = { path = "../crate/memory" }
 ucore-process = { path = "../crate/process" }
 simple-filesystem = { git = "https://github.com/wangrunji0408/SimpleFileSystem-Rust" }
-register="0.1.0"
 
 [target.'cfg(target_arch = "x86_64")'.dependencies]
 bootloader = "0.3"
@@ -45,7 +44,6 @@ riscv = { path = "../crate/riscv" }
 bbl = { path = "../crate/bbl" }
 
 [target.'cfg(target_arch = "aarch64")'.dependencies]
-cortex-a = "2.2.1"
 aarch64 = { path = "../crate/aarch64" }
 atags = { path = "../crate/atags" }
 bcm2837 = { path = "../crate/bcm2837", features = ["use_generic_timer"] }
diff --git a/kernel/src/arch/aarch64/interrupt/mod.rs b/kernel/src/arch/aarch64/interrupt/mod.rs
index 140e9b8..bba925a 100644
--- a/kernel/src/arch/aarch64/interrupt/mod.rs
+++ b/kernel/src/arch/aarch64/interrupt/mod.rs
@@ -4,7 +4,8 @@ mod handler;
 mod context;
 mod syndrome;
 
-use super::cortex_a::regs::*;
+use aarch64::regs::*;
+
 pub use self::context::*;
 pub use self::handler::*;
 
diff --git a/kernel/src/arch/aarch64/mod.rs b/kernel/src/arch/aarch64/mod.rs
index ccd6230..685072e 100644
--- a/kernel/src/arch/aarch64/mod.rs
+++ b/kernel/src/arch/aarch64/mod.rs
@@ -1,7 +1,6 @@
 //! Entrance and initialization for aarch64.
 
 extern crate atags;
-extern crate cortex_a;
 
 pub mod io;
 pub mod paging;
diff --git a/kernel/src/arch/aarch64/paging.rs b/kernel/src/arch/aarch64/paging.rs
index eab53f4..0093385 100644
--- a/kernel/src/arch/aarch64/paging.rs
+++ b/kernel/src/arch/aarch64/paging.rs
@@ -146,19 +146,29 @@ impl Entry for PageEntry {
         self.as_flags().set(EF::nG, value); // set non-global to use ASID
     }
     fn execute(&self) -> bool {
-        match self.user() {
-            true => !self.0.flags().contains(EF::XN),
-            false => !self.0.flags().contains(EF::PXN),
+        if self.user() {
+            !self.0.flags().contains(EF::XN)
+        } else {
+            !self.0.flags().contains(EF::PXN)
         }
     }
     fn set_execute(&mut self, value: bool) {
-        match self.user() {
-            true => self.as_flags().set(EF::XN, !value),
-            false => self.as_flags().set(EF::PXN, !value),
+        if self.user() {
+            self.as_flags().set(EF::XN, !value)
+        } else {
+            self.as_flags().set(EF::PXN, !value)
+        }
+    }
+    fn mmio(&self) -> bool {
+        self.0.attr().value == MairDevice::attr_value().value
+    }
+    fn set_mmio(&mut self, value: bool) {
+        if value {
+            self.0.modify_attr(MairDevice::attr_value())
+        } else {
+            self.0.modify_attr(MairNormal::attr_value())
         }
     }
-    fn mmio(&self) -> bool { self.0.attr().value == MairDevice::attr_value().value }
-    fn set_mmio(&mut self, value: bool) { self.0.modify_attr(MairDevice::attr_value()); }
 }
 
 impl PageEntry {