diff --git a/src/kernel/scheduler.rs b/src/kernel/scheduler.rs
index 07c3506..7071fbb 100644
--- a/src/kernel/scheduler.rs
+++ b/src/kernel/scheduler.rs
@@ -3,12 +3,12 @@ use std::rc::Rc;
 
 use crate::utility::list::List;
 use crate::kernel::thread::Thread;
-use super::system::System;
 use super::thread_manager::ThreadManager;
 
 #[derive(PartialEq)]
 pub struct Scheduler {
-    ready_list: List<Rc<RefCell<Thread>>>
+    ready_list: List<Rc<RefCell<Thread>>>,
+    pub thread_manager: Option<Rc<RefCell<ThreadManager>>> 
 }
 
 impl Scheduler {
@@ -18,7 +18,8 @@ impl Scheduler {
     /// Initilize the list of ready thread
     pub fn new() -> Self {
         Self {
-            ready_list: List::new()
+            ready_list: List::new(),
+            thread_manager: Option::None
         }
     }
 
@@ -53,17 +54,21 @@ impl Scheduler {
     /// ## Parameter
     /// 
     /// **next_thread** thread to dispatch to the CPU
-    pub fn switch_to(&mut self, system: &mut System, next_thread: Rc<RefCell<Thread>>) {
-        let thread_manager = system.get_thread_manager();
-        if let Some(old_thread) = thread_manager.get_g_current_thread() {
-            thread_manager.thread_save_processor_state(system, Rc::clone(&old_thread));
-            // old_thread.save_simulator_state();
+    pub fn switch_to(&mut self, next_thread: Rc<RefCell<Thread>>) {
+        if let Some(tm) = &self.thread_manager {
+            let rc = Rc::clone(&tm);
+            if let Some(old_thread) = tm.borrow_mut().get_g_current_thread() {
+                rc.borrow_mut().thread_save_processor_state(Rc::clone(&old_thread));
+                // old_thread.save_simulator_state();
 
-            if old_thread != &next_thread {
-                thread_manager.thread_restore_processor_state(system, Rc::clone(&next_thread));
-                // next_thread.restore_simulator_state();
-                thread_manager.set_g_current_thread(Option::Some(next_thread));
+                if old_thread != &next_thread {
+                    rc.borrow_mut().thread_restore_processor_state(Rc::clone(&next_thread));
+                    // next_thread.restore_simulator_state();
+                    rc.borrow_mut().set_g_current_thread(Option::Some(next_thread));
+                }
             }
+        } else {
+            panic!("thread manager shouldn't be none");
         }
     }
 }
\ No newline at end of file
diff --git a/src/kernel/synch.rs b/src/kernel/synch.rs
index 027cfce..f5741f7 100644
--- a/src/kernel/synch.rs
+++ b/src/kernel/synch.rs
@@ -40,17 +40,22 @@ impl Semaphore {
     ///	Note that thread_manager::thread_sleep assumes that interrupts are disabled
     ///	when it is called.
     ///
-    /// ### Parameters
+    /// ### Parameters TODO Refaire
     /// - *current_thread* the current thread
     /// - *machine* the machine where the threads are executed
-    pub fn p(&mut self, current_thread: Rc<RefCell<Thread>>, system: Rc<RefCell<System>>) {
-        let old_status = system.borrow_mut().get_g_machine().borrow_mut().interrupt.set_status(InterruptOff);
+    pub fn p(&mut self, system: &mut System) {
+        let old_status = system.get_machine().interrupt.set_status(InterruptOff);
         self.counter -= 1;
         if self.counter < 0 {
-            self.waiting_queue.push(Rc::clone(&current_thread));
-            self.thread_manager.borrow_mut().thread_sleep(current_thread);
+            match system.get_thread_manager().get_g_current_thread() {
+                Some(thread) => {
+                    self.waiting_queue.push(Rc::clone(thread));
+                    system.get_thread_manager().thread_sleep(system, Rc::clone(thread));
+                },
+                None => unreachable!("Current thread should not be None")
+            }
         }
-        system.borrow_mut().get_g_machine().borrow_mut().interrupt.set_status(old_status);
+        system.get_machine().interrupt.set_status(old_status);
     }
 
     /// Increment semaphore value, waking up a waiting thread if any.
@@ -63,13 +68,13 @@ impl Semaphore {
     /// ### Parameters
     /// - **machine** the machine where the threads are executed
     /// - **scheduler** the scheduler which determine which thread to execute
-    pub fn v(&mut self, system: Rc<RefCell<System>>){
-        let old_status = system.borrow_mut().get_g_machine().borrow_mut().interrupt.set_status(InterruptOff);
+    pub fn v(&mut self, system: &mut System){
+        let old_status = system.get_machine().interrupt.set_status(InterruptOff);
         self.counter += 1;
         if self.waiting_queue.peek() != None {
-            system.borrow_mut().get_thread_manager().borrow_mut().g_scheduler.ready_to_run(self.waiting_queue.pop().unwrap());
+            system.get_thread_manager().g_scheduler.ready_to_run(self.waiting_queue.pop().unwrap());
         }
-        system.borrow_mut().get_g_machine().borrow_mut().interrupt.set_status(old_status);
+        system.get_machine().interrupt.set_status(old_status);
     }
 }
 
@@ -111,23 +116,30 @@ impl Lock {
     /// ### Parameters
     /// - **current_thread** the current thread
     /// - **machine** the machine where the threads are executed
-    pub fn acquire(&mut self, current_thread: Option<Rc<RefCell<Thread>>>, system: Rc<RefCell<System>>) {
-        let old_status = system.borrow_mut().get_g_machine().borrow_mut().interrupt.set_status(InterruptOff);
+    pub fn acquire(&mut self, system: &mut System) {
+        let old_status = system.get_machine().interrupt.set_status(InterruptOff);
 
         if self.free {
             self.free = false;
-            self.owner = current_thread;
-        } else {
-            match current_thread {
-                Some(x) => {
-                    self.waiting_queue.push(Rc::clone(&x));
-                    self.thread_manager.borrow_mut().thread_sleep(x)
+            self.owner = Option::Some(match system.get_thread_manager().get_g_current_thread() {
+                Some(th) => {
+                    Rc::clone(th)
                 },
-                None => ()
+                None => unreachable!()
+            });
+        } else {
+            let t = system.get_thread_manager().get_g_current_thread();
+            match t {
+                Some(x) => {
+                    let x = Rc::clone(x);
+                    self.waiting_queue.push(Rc::clone(&x));
+                    system.thread_sleep(Rc::clone(&x));
+                },
+                None => unreachable!("Current thread should not be None")
             }
         }
 
-        system.borrow_mut().get_g_machine().borrow_mut().interrupt.set_status(old_status);
+        system.get_machine().interrupt.set_status(old_status);
     }
 
     ///     Wake up a waiter if necessary, or release it if no thread is waiting.
@@ -139,31 +151,37 @@ impl Lock {
     /// ### Parameters
     /// - **machine** the machine where the code is executed
     /// - **scheduler** the scheduler which determine which thread to execute
-    pub fn release(&mut self, system: Rc<RefCell<System>>, current_thread: Rc<RefCell<Thread>>) {
-        let old_status = system.borrow_mut().get_g_machine().borrow_mut().interrupt.set_status(InterruptOff);
+    pub fn release(&mut self, system: &mut System) {
+        let old_status = system.get_machine().interrupt.set_status(InterruptOff);
         
-        if self.held_by_current_thread(current_thread) {
-            if self.waiting_queue.peek() != None {
-                self.owner = Some(self.waiting_queue.pop().unwrap());
-                let sys = system.borrow_mut();
-                let tm = sys.get_thread_manager();
-                let scheduler = &mut tm.borrow_mut().g_scheduler;
-                match &self.owner {
-                    Some(x) => scheduler.ready_to_run(Rc::clone(&x)),
-                    None => ()
+        match system.get_thread_manager().get_g_current_thread() {
+            Some(thread) => {
+                if self.held_by_current_thread(system) {
+                    if self.waiting_queue.peek() != None {
+                        self.owner = Some(self.waiting_queue.pop().unwrap());
+                        match &self.owner {
+                            Some(x) => system.get_thread_manager().g_scheduler.ready_to_run(Rc::clone(&x)),
+                            None => ()
+                        }
+                    } else {
+                        self.free = true;
+                        self.owner = None;
+                    }
                 }
-            } else {
-                self.free = true;
-                self.owner = None;
             }
+            None => ()
         }
 
-        system.borrow_mut().get_g_machine().borrow_mut().interrupt.set_status(old_status);
+        system.get_machine().interrupt.set_status(old_status);
     }
 
-    pub fn held_by_current_thread(&mut self, current_thread: Rc<RefCell<Thread>>) -> bool {
+    pub fn held_by_current_thread(&mut self, system: &mut System) -> bool {
         match &self.owner {
-            Some(x) => Rc::ptr_eq(&x, &current_thread),
+            Some(x) => 
+                match system.get_thread_manager().get_g_current_thread() {
+                    Some(thread) => Rc::ptr_eq(&x, thread),
+                    None => false
+                }
             None => false
         }
     }
@@ -195,11 +213,11 @@ impl Condition {
     /// ### Parameters
     /// - **current_thread** the current thread
     /// - **machine** the machine where threads are executed
-    pub fn wait(&mut self, current_thread: Rc<RefCell<Thread>>, machine: &mut Machine) {
+    pub fn wait(&mut self, current_thread: Rc<RefCell<Thread>>, machine: &mut Machine, system: &mut System) {
         let old_status = machine.interrupt.set_status(InterruptOff);
 
         self.waiting_queue.push(Rc::clone(&current_thread));
-        self.thread_manager.borrow_mut().thread_sleep(current_thread);
+        self.thread_manager.borrow_mut().thread_sleep(system, current_thread);
 
         machine.interrupt.set_status(old_status);
     }
diff --git a/src/kernel/system.rs b/src/kernel/system.rs
index e3aaf73..7383911 100644
--- a/src/kernel/system.rs
+++ b/src/kernel/system.rs
@@ -6,7 +6,7 @@ use std::{cell::RefCell, rc::Rc};
 
 use crate::simulator::machine::Machine;
 
-use super::thread_manager::ThreadManager;
+use super::{thread_manager::ThreadManager, thread::Thread};
 
 /// This macro properly initializes the system
 #[macro_export]
@@ -46,17 +46,23 @@ impl System {
         }
     }
 
+    /// Sets a thread asleep
+    /// 
+    pub fn thread_sleep(&mut self, thread: Rc<RefCell<Thread>>) {
+        &self.thread_manager.thread_sleep(self, thread);
+    }
+
     // GETTERS
 
     /// Returns the Machine
     /// 
     /// Useful to access RAM, devices, ...
-    pub fn get_machine(&self) -> &Machine {
-        &self.machine
+    pub fn get_machine(&mut self) -> &mut Machine {
+        &mut self.machine
     }
 
-    pub fn get_thread_manager(&self) -> &ThreadManager {
-        &self.thread_manager
+    pub fn get_thread_manager(&mut self) -> &mut ThreadManager {
+        &mut self.thread_manager
     }
 
     // Setters
diff --git a/src/kernel/thread_manager.rs b/src/kernel/thread_manager.rs
index 5820906..2d5cc06 100644
--- a/src/kernel/thread_manager.rs
+++ b/src/kernel/thread_manager.rs
@@ -70,7 +70,7 @@ impl ThreadManager {
         if let Some(next_thread) = next_thread {
             let scheduler = &mut self.g_scheduler;
             scheduler.ready_to_run(thread);
-            scheduler.switch_to(system, next_thread);
+            scheduler.switch_to(next_thread);
         }
         machine.interrupt.set_status(old_status);
     }
@@ -86,7 +86,7 @@ impl ThreadManager {
             machine.interrupt.idle();
             next_thread = self.g_scheduler.find_next_to_run();
         }
-        self.g_scheduler.switch_to(system, Rc::clone(&next_thread.unwrap()));
+        self.g_scheduler.switch_to(Rc::clone(&next_thread.unwrap()));
     }
 
     /// Finish the execution of the thread and prepare its deallocation