diff --git a/kernel/src/arch/aarch64/board/raspi3/irq.rs b/kernel/src/arch/aarch64/board/raspi3/irq.rs
index d7d43b2..e01a2c3 100644
--- a/kernel/src/arch/aarch64/board/raspi3/irq.rs
+++ b/kernel/src/arch/aarch64/board/raspi3/irq.rs
@@ -5,8 +5,7 @@ use super::bcm2837::interrupt::{Controller, Interrupt};
 pub fn handle_irq(tf: &mut TrapFrame) {
     let controller = Timer::new();
     if controller.is_pending() {
-        println!("Timer tick {}...", super::timer::get_cycle());
         super::timer::set_next();
-        // ::trap::timer();
+        ::trap::timer();
     }
 }
diff --git a/kernel/src/arch/aarch64/board/raspi3/timer.rs b/kernel/src/arch/aarch64/board/raspi3/timer.rs
index 2e54fb3..4cc0be0 100644
--- a/kernel/src/arch/aarch64/board/raspi3/timer.rs
+++ b/kernel/src/arch/aarch64/board/raspi3/timer.rs
@@ -12,6 +12,6 @@ pub fn get_cycle() -> u64 {
 }
 
 pub fn set_next() {
-    // 1000 ms
-    timer::tick_in(1000 * 1000);
+    // 10 ms
+    timer::tick_in(10 * 1000);
 }
diff --git a/kernel/src/arch/aarch64/boot/boot.S b/kernel/src/arch/aarch64/boot/boot.S
index 1740a20..b8a142e 100644
--- a/kernel/src/arch/aarch64/boot/boot.S
+++ b/kernel/src/arch/aarch64/boot/boot.S
@@ -18,6 +18,9 @@ setup:
     # store the desired EL1 stack pointer in x1
     adr     x1, _start
 
+    # use SP_ELx for Exception level ELx
+    msr     SPsel, #1
+
     # read the current exception level into x0 (ref: C5.2.1)
     mrs     x0, CurrentEL
     and     x0, x0, #0b1100
diff --git a/kernel/src/arch/aarch64/interrupt/context.rs b/kernel/src/arch/aarch64/interrupt/context.rs
index 9bc2e77..df2b5b3 100644
--- a/kernel/src/arch/aarch64/interrupt/context.rs
+++ b/kernel/src/arch/aarch64/interrupt/context.rs
@@ -116,6 +116,8 @@ impl Context {
         tlbi vmalle1is              // invalidate the TLB entry for the entry that changes
         dsb ish                     // ensure TLB invalidation is complete
         isb                         // synchronize context on this processor
+
+        str xzr, [x1]
         ret"
         : : : : "volatile" );
     }
diff --git a/kernel/src/arch/aarch64/interrupt/mod.rs b/kernel/src/arch/aarch64/interrupt/mod.rs
index 2ced283..140e9b8 100644
--- a/kernel/src/arch/aarch64/interrupt/mod.rs
+++ b/kernel/src/arch/aarch64/interrupt/mod.rs
@@ -4,6 +4,7 @@ mod handler;
 mod context;
 mod syndrome;
 
+use super::cortex_a::regs::*;
 pub use self::context::*;
 pub use self::handler::*;
 
@@ -34,8 +35,9 @@ pub unsafe fn disable() {
 /// return: status(usize)
 #[inline(always)]
 pub unsafe fn disable_and_store() -> usize {
-    // TODO
-    0
+    let daif = DAIF.get() as usize;
+    disable();
+    daif
 }
 
 /// Use the original status to restore the process
@@ -44,5 +46,5 @@ pub unsafe fn disable_and_store() -> usize {
 /// * flags:  original status(usize)
 #[inline(always)]
 pub unsafe fn restore(flags: usize) {
-    // TODO
+    DAIF.set(flags as u32);
 }
diff --git a/kernel/src/arch/aarch64/mod.rs b/kernel/src/arch/aarch64/mod.rs
index 8c9585d..35613ab 100644
--- a/kernel/src/arch/aarch64/mod.rs
+++ b/kernel/src/arch/aarch64/mod.rs
@@ -1,6 +1,7 @@
 //! Entrance and initialization for aarch64.
 
 extern crate atags;
+extern crate cortex_a;
 
 pub mod io;
 pub mod paging;
@@ -13,72 +14,16 @@ pub mod board;
 
 pub use self::board::timer;
 
-/// TODO
 /// The entry point of kernel
 #[no_mangle] // don't mangle the name of this function
 pub extern "C" fn rust_main() -> ! {
     // Init board to enable serial port.
     board::init();
-
-    // First init log mod, so that we can print log info.
-    // FIXME
-    ::logging::init();
-
-    let (start, end) = memory::memory_map().expect("failed to find memory map");
-    println!("The value of start is: {:#x?}, end is {:#x?}", start, end);
-
+    ::logging::init(); // FIXME
     interrupt::init();
     memory::init();
     timer::init();
-
-    //let mut v = vec![];
-    //for i in 0..1000 {
-    //    v.push(i);
-    //    println!("{:?}", v);
-    //}
-
-    ::process::init();
-
-    unsafe { interrupt::enable(); }
-
-    super::fs::show_logo();
-
-    loop {
-        print!(">> ");
-        loop {
-            let c = io::getchar();
-            match c {
-                '\u{7f}' => {
-                    print!("\u{7f}");
-                }
-                'b' => unsafe {
-                    println!("brk 233");
-                    asm!("brk 233");
-                },
-                'c' => unsafe {
-                    println!("sys_putc");
-                    asm!(
-                        "mov x8, #30
-                         mov x0, #65
-                         svc 0"
-                    );
-                },
-                't' => unsafe {
-                    println!("{}", timer::get_cycle());
-                },
-                ' '...'\u{7e}' => {
-                    print!("{}", c);
-                }
-                '\n' | '\r' => {
-                    print!("\n");
-                    break;
-                }
-                _ => {}
-            }
-        }
-    }
-
-    // ::kmain();
+    ::kmain();
 }
 
 global_asm!(include_str!("boot/boot.S"));
diff --git a/kernel/src/fs.rs b/kernel/src/fs.rs
index d682236..6e4e0a3 100644
--- a/kernel/src/fs.rs
+++ b/kernel/src/fs.rs
@@ -26,6 +26,62 @@ pub fn show_logo() {
     println!("{}", LOGO);
 }
 
+#[inline(always)]
+fn sys_call(id: usize, arg0: usize, arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) -> i32 {
+    let ret: i32;
+    unsafe {
+        #[cfg(target_arch = "riscv32")]
+            asm!("ecall"
+            : "={x10}" (ret)
+            : "{x10}" (id), "{x11}" (arg0), "{x12}" (arg1), "{x13}" (arg2), "{x14}" (arg3), "{x15}" (arg4), "{x16}" (arg5)
+            : "memory"
+            : "volatile");
+        #[cfg(target_arch = "x86_64")]
+            asm!("int 0x40"
+            : "={rax}" (ret)
+            : "{rax}" (id), "{rdi}" (arg0), "{rsi}" (arg1), "{rdx}" (arg2), "{rcx}" (arg3), "{r8}" (arg4), "{r9}" (arg5)
+            : "memory"
+            : "intel" "volatile");
+        #[cfg(target_arch = "aarch64")]
+            asm!("svc 0"
+            : "={x0}" (ret)
+            : "{x8}" (id), "{x0}" (arg0), "{x1}" (arg1), "{x2}" (arg2), "{x3}" (arg3), "{x4}" (arg4), "{x5}" (arg5)
+            : "memory"
+            : "volatile");
+    }
+    ret
+}
+
+pub fn test_shell(prefix: &str) -> ! {
+    show_logo();
+    loop {
+        print!("{}", prefix);
+        loop {
+            let c = super::arch::io::getchar();
+            match c {
+                '\u{7f}' => {
+                    print!("\u{7f}");
+                }
+                'c' => unsafe {
+                    print!("sys_putc: ");
+                    sys_call(30, 'A' as usize, 0, 0, 0, 0, 0);
+                },
+                't' => unsafe {
+                    println!("sys_get_time: {}", sys_call(17, 0, 0, 0, 0, 0, 0));
+                },
+                ' '...'\u{7e}' => {
+                    print!("{}", c);
+                }
+                '\n' | '\r' => {
+                    print!("\n");
+                    break;
+                }
+                _ => {}
+            }
+        }
+    }
+}
+
 pub fn shell() {
     show_logo();
 
diff --git a/kernel/src/lib.rs b/kernel/src/lib.rs
index 8305a77..4474c9c 100644
--- a/kernel/src/lib.rs
+++ b/kernel/src/lib.rs
@@ -66,9 +66,14 @@ pub mod arch;
 
 pub fn kmain() -> ! {
     process::init();
+
+    use process::*;
+    processor().add(Context::new_kernel(kernel_proc2, 2333));
+    processor().add(Context::new_user_test(kernel_proc3));
+
     unsafe { arch::interrupt::enable(); }
 
-    fs::shell();
+    // fs::shell();
 
 //    thread::test::local_key();
 //    thread::test::unpack();
@@ -86,3 +91,12 @@ pub fn kmain() -> ! {
 /// It should be defined in memory mod, but in Rust `global_allocator` must be in root mod.
 #[global_allocator]
 static HEAP_ALLOCATOR: LockedHeap = LockedHeap::empty();
+
+
+pub extern "C" fn kernel_proc2(arg: usize) -> ! {
+    fs::test_shell(&format!("proc2-{}>> ", arg));
+}
+
+pub extern "C" fn kernel_proc3(arg: usize) -> ! {
+    fs::test_shell(&format!("proc3-{}$ ", arg));
+}
diff --git a/kernel/src/process/context.rs b/kernel/src/process/context.rs
index d4ebd96..f20d209 100644
--- a/kernel/src/process/context.rs
+++ b/kernel/src/process/context.rs
@@ -33,6 +33,15 @@ impl Context {
         }
     }
 
+    pub fn new_user_test(entry: extern fn(usize) -> !) -> Self {
+        let ms = MemorySet::new();
+        let user_stack = ::memory::alloc_stack();
+        Context {
+            arch: unsafe { ArchContext::new_user_thread(entry as usize, user_stack.top - 8, ms.kstack_top(), false, ms.token()) },
+            memory_set: ms,
+        }
+    }
+
     /// Make a new user thread from ELF data
     pub fn new_user(data: &[u8]) -> Self {
         // Parse elf
@@ -143,4 +152,4 @@ fn memory_attr_from(elf_flags: Flags) -> MemoryAttr {
     // TODO: handle readonly
     if elf_flags.is_execute() { flags = flags.execute(); }
     flags
-}
\ No newline at end of file
+}
diff --git a/kernel/src/process/mod.rs b/kernel/src/process/mod.rs
index 09636cd..5ee8cd2 100644
--- a/kernel/src/process/mod.rs
+++ b/kernel/src/process/mod.rs
@@ -1,39 +1,32 @@
 use spin::Once;
-use sync::{SpinNoIrqLock, Mutex, MutexGuard, SpinNoIrq};
+use sync::{Mutex, MutexGuard, SpinNoIrq, SpinNoIrqLock};
 pub use self::context::Context;
 pub use ucore_process::processor::{*, Context as _whatever};
 pub use ucore_process::scheduler::*;
 pub use ucore_process::thread::*;
 
-use arch::timer;
-
 mod context;
 
 type Processor = Processor_<Context, StrideScheduler>;
 
 pub fn init() {
-    PROCESSOR.call_once(||
+    PROCESSOR.call_once(|| {
         SpinNoIrqLock::new({
             let mut processor = Processor::new(
                 unsafe { Context::new_init() },
                 // NOTE: max_time_slice <= 5 to ensure 'priority' test pass
                 StrideScheduler::new(5),
             );
-            extern fn idle1(arg: usize) -> ! {
-                loop {
-                    println!("idle 1 {}", timer::get_cycle());
-                }
-            }
-            extern fn idle2(arg: usize) -> ! {
+            extern "C" fn idle(arg: usize) -> ! {
                 loop {
-                    println!("idle 2 {}", timer::get_cycle());
+                    #[cfg(target_arch = "aarch64")]
+                    unsafe { asm!("wfi" :::: "volatile") }
                 }
             }
-            processor.add(Context::new_kernel(idle1, 0));
-            processor.add(Context::new_kernel(idle2, 0));
+            processor.add(Context::new_kernel(idle, 0));
             processor
         })
-    );
+    });
     info!("process init end");
 }
 
diff --git a/kernel/src/sync/mutex.rs b/kernel/src/sync/mutex.rs
index c8e62ea..6e4a24c 100644
--- a/kernel/src/sync/mutex.rs
+++ b/kernel/src/sync/mutex.rs
@@ -217,6 +217,8 @@ impl MutexSupport for Spin {
                 asm!("pause" :::: "volatile");
             #[cfg(target_arch = "riscv32")]
                 asm!("nop" :::: "volatile");
+            #[cfg(target_arch = "aarch64")]
+                asm!("yield" :::: "volatile");
         }
     }
     fn before_lock() -> Self::GuardData {}
@@ -247,6 +249,8 @@ impl MutexSupport for SpinNoIrq {
                 asm!("pause" :::: "volatile");
             #[cfg(target_arch = "riscv32")]
                 asm!("nop" :::: "volatile");
+            #[cfg(target_arch = "aarch64")]
+                asm!("yield" :::: "volatile");
         }
     }
     fn before_lock() -> Self::GuardData {
@@ -267,4 +271,4 @@ impl MutexSupport for Condvar {
     fn after_unlock(&self) {
         self.notify_one();
     }
-}
\ No newline at end of file
+}