diff --git a/Lab3/ramdisk/userland.bin b/Lab3/ramdisk/userland.bin
index 80cd5ef9..4d1e2414 100755
Binary files a/Lab3/ramdisk/userland.bin and b/Lab3/ramdisk/userland.bin differ
diff --git a/Lab3/user/chcore-libc/libchcore/cmake/do_override_dir.sh b/Lab3/user/chcore-libc/libchcore/cmake/do_override_dir.sh
index 8b92ea14..bac69e4c 100644
--- a/Lab3/user/chcore-libc/libchcore/cmake/do_override_dir.sh
+++ b/Lab3/user/chcore-libc/libchcore/cmake/do_override_dir.sh
@@ -14,15 +14,15 @@ set -e
 self=`basename "$0"`
 
 function usage {
-    echo "Usage: $self [overrides_absolute_path] [target_absolute_path]"
+    echo "Usage: $self [[overrides_absolute_path]] [[target_absolute_path]]"
     exit 1
 }
 
-if [ "$#" -ne 2 ]; then
+if [[ "$#" -ne 2 ]]; then
     usage
 fi
 
-if [[ $1 != /* ]] || [[ $2 != /* ]]; then
+if [[[[ $1 != /* ]]]] || [[[[ $2 != /* ]]]]; then
     usage 
 fi
 
@@ -63,28 +63,29 @@ function traverse {
         rel_path=${file#$overrides/}
         target_file=$target/$rel_path
 
-        if [ -d "$file" ]; then
-            if [ ! -e "$target_file" ]; then
+        if [[ -d "$file" ]]; then
+            if [[ ! -e "$target_file" ]]; then
                 ln -sf "$file" "$target_file"
                 echo "--- Overrided ${target_file} with ${file} symlink"
-            elif [ ! -L "$target_file" ]; then
+            elif [[ ! -L "$target_file" ]]; then
                 traverse "$file"
             else
                 echo "--- Target directory ${target_file} has been overrided, skipping..."
             fi
-        elif [ -f "$file" ]; then
-            if [ ! -s "$file" ]; then
-                if [ -e "$target_file" ]; then
-                    mv "$target_file" "$target_file.bak"
+        elif [[ -f "$file" ]]; then
+            if [[ "$file" == *.del ]]; then
+                target_file="${target_file%.del}"
+                if [[ -e "${target_file}" ]]; then
+                    mv "${target_file}" "$target_file.bak"
                     echo "--- Overrided ${target_file} with ${file}"
                 else
                     echo "--- Target file ${target_file} has been deleted, skipping..."
                 fi
             else
-                if [ ! -e "$target_file" ]; then
+                if [[ ! -e "$target_file" ]]; then
                     ln -sf "$file" "$target_file"
                     echo "--- Overrided ${target_file} with ${file}"
-                elif [ ! -L "$target_file" ]; then
+                elif [[ ! -L "$target_file" ]]; then
                     mv "$target_file" "$target_file.bak"
                     ln -sf "$file" "$target_file"
                     echo "--- Overrided ${target_file} with ${file}"
diff --git a/Lab3/user/chcore-libc/libchcore/porting/overrides/src/thread/aarch64/__thread_exit.S b/Lab3/user/chcore-libc/libchcore/porting/overrides/src/thread/aarch64/__thread_exit.S
old mode 100755
new mode 100644
diff --git a/Lab3/user/chcore-libc/libchcore/porting/overrides/src/thread/aarch64/__unmapself.s.del b/Lab3/user/chcore-libc/libchcore/porting/overrides/src/thread/aarch64/__unmapself.s.del
new file mode 100644
index 00000000..e69de29b
diff --git a/Lab4/filelist.mk b/Lab4/filelist.mk
index a0ff51d1..c25f517f 100644
--- a/Lab4/filelist.mk
+++ b/Lab4/filelist.mk
@@ -7,7 +7,7 @@ SCHEDULER := $(SCHED)/sched.c
 RR := $(SCHED)/policy_rr.c
 ARCH_TIMER := $(ARCH_IRQ)/timer.c
 IRQ := $(ARCH_IRQ)/irq.c
-KERNEL_TIMER := $(IRQ)/timer.c
+KERNEL_TIMER := $(KERNEL_IRQ)/timer.c
 CONNECTION := $(IPC)/connection.c
 
 FILES := $(SCHEDULER) \
diff --git a/Lab4/kernel/CMakeLists.txt b/Lab4/kernel/CMakeLists.txt
index bd8724c4..80237fb4 100644
--- a/Lab4/kernel/CMakeLists.txt
+++ b/Lab4/kernel/CMakeLists.txt
@@ -137,7 +137,7 @@ macro(_kernel_incbin _binary_name _binary_path)
 endmacro()
 
 # Include essential user-level binaries
-_kernel_incbin(procmgr_bin ${CMAKE_CURRENT_SOURCE_DIR}/../user/procmgr)
+_kernel_incbin(procmgr_bin ${CHCORE_USER_INSTALL_DIR}/system-servers/procmgr/procmgr)
 
 # Rebuild kernel when ramdisk changes
 add_custom_target(touch-inc-procmgr
diff --git a/Lab4/user/chcore-libc/libchcore/cmake/do_override_dir.sh b/Lab4/user/chcore-libc/libchcore/cmake/do_override_dir.sh
index 8b92ea14..bac69e4c 100644
--- a/Lab4/user/chcore-libc/libchcore/cmake/do_override_dir.sh
+++ b/Lab4/user/chcore-libc/libchcore/cmake/do_override_dir.sh
@@ -14,15 +14,15 @@ set -e
 self=`basename "$0"`
 
 function usage {
-    echo "Usage: $self [overrides_absolute_path] [target_absolute_path]"
+    echo "Usage: $self [[overrides_absolute_path]] [[target_absolute_path]]"
     exit 1
 }
 
-if [ "$#" -ne 2 ]; then
+if [[ "$#" -ne 2 ]]; then
     usage
 fi
 
-if [[ $1 != /* ]] || [[ $2 != /* ]]; then
+if [[[[ $1 != /* ]]]] || [[[[ $2 != /* ]]]]; then
     usage 
 fi
 
@@ -63,28 +63,29 @@ function traverse {
         rel_path=${file#$overrides/}
         target_file=$target/$rel_path
 
-        if [ -d "$file" ]; then
-            if [ ! -e "$target_file" ]; then
+        if [[ -d "$file" ]]; then
+            if [[ ! -e "$target_file" ]]; then
                 ln -sf "$file" "$target_file"
                 echo "--- Overrided ${target_file} with ${file} symlink"
-            elif [ ! -L "$target_file" ]; then
+            elif [[ ! -L "$target_file" ]]; then
                 traverse "$file"
             else
                 echo "--- Target directory ${target_file} has been overrided, skipping..."
             fi
-        elif [ -f "$file" ]; then
-            if [ ! -s "$file" ]; then
-                if [ -e "$target_file" ]; then
-                    mv "$target_file" "$target_file.bak"
+        elif [[ -f "$file" ]]; then
+            if [[ "$file" == *.del ]]; then
+                target_file="${target_file%.del}"
+                if [[ -e "${target_file}" ]]; then
+                    mv "${target_file}" "$target_file.bak"
                     echo "--- Overrided ${target_file} with ${file}"
                 else
                     echo "--- Target file ${target_file} has been deleted, skipping..."
                 fi
             else
-                if [ ! -e "$target_file" ]; then
+                if [[ ! -e "$target_file" ]]; then
                     ln -sf "$file" "$target_file"
                     echo "--- Overrided ${target_file} with ${file}"
-                elif [ ! -L "$target_file" ]; then
+                elif [[ ! -L "$target_file" ]]; then
                     mv "$target_file" "$target_file.bak"
                     ln -sf "$file" "$target_file"
                     echo "--- Overrided ${target_file} with ${file}"
diff --git a/Lab4/user/chcore-libc/libchcore/porting/overrides/src/thread/aarch64/__unmapself.s.del b/Lab4/user/chcore-libc/libchcore/porting/overrides/src/thread/aarch64/__unmapself.s.del
new file mode 100644
index 00000000..e69de29b
diff --git a/Lab4/user/procmgr b/Lab4/user/procmgr
deleted file mode 100755
index def3709e..00000000
Binary files a/Lab4/user/procmgr and /dev/null differ
diff --git a/Lab4/user/system-services/system-servers/procmgr/procmgr.c b/Lab4/user/system-services/system-servers/procmgr/procmgr.c
index 48a6a593..33628190 100644
--- a/Lab4/user/system-services/system-servers/procmgr/procmgr.c
+++ b/Lab4/user/system-services/system-servers/procmgr/procmgr.c
@@ -645,20 +645,10 @@ void boot_default_apps(void)
 
         /* Start shell. */
 
-        char *userland_argv= "userland.bin";
+        char *test_ipc_argv= "test_ipc.bin";
         (void)procmgr_launch_process(1,
-                                     &userland_argv,
-                                     "userland",
-                                     true,
-                                     INIT_BADGE,
-                                     NULL,
-                                     COMMON_APP,
-                                     NULL);
-
-        char *hello_world_argv= "hello_world.bin";
-        (void)procmgr_launch_process(1,
-                                     &hello_world_argv,
-                                     "hello_world",
+                                     &test_ipc_argv,
+                                     "test_ipc",
                                      true,
                                      INIT_BADGE,
                                      NULL,