diff --git a/.gitignore b/.gitignore
index e72d4a38..396bafc5 100644
--- a/.gitignore
+++ b/.gitignore
@@ -16,6 +16,7 @@
 *.s
 *.e
 *.d
+pal.map
 
 # object file/libraries
 *.a
diff --git a/Jenkinsfiles/Linux b/Jenkinsfiles/Linux
index ff29dbe7..9f806b20 100644
--- a/Jenkinsfiles/Linux
+++ b/Jenkinsfiles/Linux
@@ -17,6 +17,10 @@ pipeline {
                             cd Pal/ipc/linux
                             make KERNELDIR=/lib/modules/4.4.0-161-generic/build
                            '''
+                        sh '''
+                            cd Pal/src
+                            make -j 8 PAL_HOST=Skeleton WERROR=1
+                           '''
                     }
                 }
                 stage('Test') {
diff --git a/Jenkinsfiles/Linux-Debug b/Jenkinsfiles/Linux-Debug
index ebd15c44..bf33076d 100644
--- a/Jenkinsfiles/Linux-Debug
+++ b/Jenkinsfiles/Linux-Debug
@@ -9,6 +9,10 @@ pipeline {
                             make -j 8 DEBUG=1 WERROR=1
                             make -j 8 DEBUG=1 WERROR=1 test
                            '''
+                        sh '''
+                            cd Pal/src
+                            make -j 8 PAL_HOST=Skeleton DEBUG=1 WERROR=1
+                           '''
                     }
                 }
                 stage('Test') {
diff --git a/Makefile.rules b/Makefile.rules
index f61b4335..54d9ef24 100644
--- a/Makefile.rules
+++ b/Makefile.rules
@@ -93,7 +93,7 @@ quiet_cmd_cpp_s_S = [ $@ ]
 
 # LD
 quiet_cmd_ld_so_o = [ $@ ]
-      cmd_ld_so_o = $(LD) $(LDFLAGS) $(LDFLAGS-$@) -o $@ $(filter-out %.map %.lds,$^) -soname $(notdir $@)
+      cmd_ld_so_o = $(LD) $(LDFLAGS) $(LDFLAGS-$@) -o $@ $(filter-out pal-symbols %.map %.map.template %.lds,$^) -soname $(notdir $@)
 
 # AR
 quiet_cmd_ar_so_o = [ $@ ]
@@ -104,7 +104,7 @@ quiet_cmd_ar_a_o = [ $@ ]
 
 # LD only
 quiet_cmd_ld = [ $@ ]
-      cmd_ld = $(LD) $(LDFLAGS) $(LDFLAGS-$@) -o $@ $(filter-out %.map %.lds,$^)
+      cmd_ld = $(LD) $(LDFLAGS) $(LDFLAGS-$@) -o $@ $(filter-out pal-symbols %.map %.map.template %.lds,$^)
 
 # OBJCOPY
 quiet_cmd_objcopy = [ $@ ]
@@ -142,3 +142,13 @@ quiet_cmd_sgx_manifest_dependency = [ $@ ]
 	 awk -F= '/^\s*sgx.trusted_files./{file=$$2; gsub("file:", "", file); printf(" \\\n\t%s", file)}' $<; \
 	 awk -F= '/^\s*sgx.trusted_children./{file=$$2; gsub("file:", "", file); printf(" \\\n\t%s", file); gsub(".sig", "", file); printf(" \\\n\t%s.manifest.sgx", file)}' $<; \
 	 echo "") > $@
+
+# pal map
+PAL_SYMBOL_FILE = $(dir $(abspath $(lastword $(MAKEFILE_LIST))))Pal/src/pal-symbols
+PAL_SYMBOLS = $(shell sed -e 's|$$|;|g' $(PAL_SYMBOL_FILE))
+
+quiet_cmd_pal_map = [ $@ ]
+      cmd_pal_map = sed -e 's|\$$(PAL_SYMBOLS)|$(PAL_SYMBOLS)|g' $< > $@
+
+pal.map: pal.map.template $(PAL_SYMBOL_FILE)
+	$(call cmd,pal_map)
diff --git a/Pal/src/Makefile b/Pal/src/Makefile
index 31efd587..de27e49f 100644
--- a/Pal/src/Makefile
+++ b/Pal/src/Makefile
@@ -59,7 +59,9 @@ export DEBUG
 #       libpal-{Host Name}.so: dynamic-linking library
 #       pal_gdb-{Host Name}:   debugger for PAL (as an executable)
 
-runtime_loader = $(RUNTIME_DIR)/pal-$(PAL_HOST)
+ifneq ($(pal_loader),)
+	runtime_loader += $(RUNTIME_DIR)/pal-$(PAL_HOST)
+endif
 
 ifneq ($(pal_lib),)
 	runtime_lib += $(RUNTIME_DIR)/libpal-$(PAL_HOST)$(suffix $(pal_lib))
@@ -99,8 +101,10 @@ $(host_lib): host_lib_recurse
 
 $(pal_loader): $(host_lib)
 
+ifneq ($(pal_loader),)
 $(runtime_loader): $(pal_loader)
 	$(call cmd,ln_sf)
+endif
 
 ifneq ($(pal_lib),)
 $(pal_lib): $(addprefix $(OBJ_DIR)/,$(addsuffix .o,$(objs))) \
diff --git a/Pal/src/host/FreeBSD/Makefile b/Pal/src/host/FreeBSD/Makefile
index 30457ccd..7c8bd388 100644
--- a/Pal/src/host/FreeBSD/Makefile
+++ b/Pal/src/host/FreeBSD/Makefile
@@ -5,7 +5,7 @@ CFLAGS	+= -I. -Iinclude -I../.. -I../../../include -I../../../lib -I../../../ipc
 	   -I../../../linux-kernel/graphene
 ASFLAGS += -I. -Iinclude -I../.. -I../../../include
 
-host_target = libpal-FreeBSD.a ../../pal-gdb
+host_files = libpal-FreeBSD.a pal.map ../../pal-gdb
 
 defs	= -DIN_PAL -DPAL_DIR="$(PAL_DIR)"
 CFLAGS += $(defs)
@@ -17,7 +17,7 @@ graphene_lib = .lib/graphene-lib.a
 headers	= $(wildcard *.h) $(wildcard ../../*.h) $(wildcard ../../../lib/*.h)
 
 .PHONY: all
-all: $(host_target)
+all: $(host_files)
 
 ifeq ($(DEBUG),1)
 CC += -g -gdwarf-2 -gstrict-dwarf
@@ -50,8 +50,8 @@ libpal-FreeBSD.a: $(addsuffix .o,$(objs)) $(graphene_lib)
 
 include ../../../../Makefile.rules
 
-CLEAN_FILES += $(notdir $(pal_static) $(pal_lib) $(pal_loader))
+CLEAN_FILES += $(notdir $(pal_static) $(pal_lib) $(pal_sec) $(pal_loader))
 
 .PHONY: clean
 clean:
-	rm -f $(addsuffix .o,$(objs)) $(host_target) $(CLEAN_FILES)
+	rm -f $(addsuffix .o,$(objs)) $(host_files) $(CLEAN_FILES)
diff --git a/Pal/src/host/FreeBSD/Makefile.am b/Pal/src/host/FreeBSD/Makefile.am
index 4e6cb3ac..1ec58780 100644
--- a/Pal/src/host/FreeBSD/Makefile.am
+++ b/Pal/src/host/FreeBSD/Makefile.am
@@ -16,6 +16,6 @@ endif
 
 pal_loader = $(HOST_DIR)/libpal.so
 pal_lib = $(HOST_DIR)/libpal.so
-pal_lib_deps = $(HOST_DIR)/pal.map $(HOST_DIR)/pal.lds
+pal_lib_deps = pal-symbols $(HOST_DIR)/pal.map.template $(HOST_DIR)/pal.lds
 pal_lib_post =
 pal_static = $(HOST_DIR)/libpal.a
diff --git a/Pal/src/host/FreeBSD/pal.map b/Pal/src/host/FreeBSD/pal.map
deleted file mode 100644
index f21eeb25..00000000
--- a/Pal/src/host/FreeBSD/pal.map
+++ /dev/null
@@ -1,54 +0,0 @@
-PAL {
-    global:
-        # Drawbridge ABIs
-        DkVirtualMemoryAlloc; DkVirtualMemoryFree; DkVirtualMemoryProtect;
-        DkThreadCreate; DkThreadDelayExecution;
-        DkThreadYieldExecution; DkThreadExit; DkThreadResume;
-
-        DkSemaphoreCreate; DkNotificationEventCreate;
-        DkSynchronizationEventCreate;
-        DkSemaphoreRelease;
-        DkEventSet;  DkEventClear;
-        DkObjectsWaitAny;
-
-        DkStreamOpen; DkStreamRead; DkStreamWrite;
-        DkStreamMap; DkStreamUnmap; DkStreamSetLength;
-        DkStreamFlush; DkStreamDelete;
-        DkSendHandle; DkReceiveHandle; # Added by us
-        DkStreamWaitForClient;
-        DkStreamGetName;
-        DkStreamAttributesQueryByHandle; DkStreamAttributesQuery;
-
-        DkProcessCreate; DkProcessExit;
-
-        DkSystemTimeQuery; DkRandomBitsRead;
-        DkInstructionCacheFlush;
-        DkObjectReference; DkObjectClose;
-        # objects checkpoint?
-        # objects reload?
-
-        # The ABIs we added in the paper
-        DkSetExceptionHandler; DkExceptionReturn; # exceptions
-        DkCreatePhysicalMemoryChannel; # IPC
-        DkPhysicalMemoryCommit; # IPC
-        DkPhysicalMemoryMap; # IPC
-        DkSegmentRegister; # set segmentation registers
-        DkStreamChangeName;
-        DkStreamAttributesSetByHandle;
-        DkMemoryAvailableQuota;
-
-        # Debugging ABIs
-        pal_printf; DkDebugAttachBinary; DkDebugDetachBinary;
-
-        # Control block
-        pal_control_addr; pal_sec;
-
-        # debugger interface
-        r_debug;
-
-    local: *;
-};
-PAL_PRIVATE {
-    global:
-        r_debug_state;
-};
diff --git a/Pal/src/host/FreeBSD/pal.map.template b/Pal/src/host/FreeBSD/pal.map.template
new file mode 100644
index 00000000..21ddc7f2
--- /dev/null
+++ b/Pal/src/host/FreeBSD/pal.map.template
@@ -0,0 +1,8 @@
+PAL {
+    global: $(PAL_SYMBOLS) r_debug;
+    local: *;
+};
+PAL_PRIVATE {
+    global:
+        r_debug_state;
+};
diff --git a/Pal/src/host/Linux-SGX/Makefile b/Pal/src/host/Linux-SGX/Makefile
index 19fc731c..49be0441 100644
--- a/Pal/src/host/Linux-SGX/Makefile
+++ b/Pal/src/host/Linux-SGX/Makefile
@@ -4,7 +4,7 @@ include Makefile.am
 CFLAGS	+= -I. -Iinclude -I../.. -I../../../include -I../../../lib -Isgx-driver
 ASFLAGS += -I. -I../.. -I../../../include
 
-host_files = libpal-Linux-SGX.a pal-sgx debugger/sgx_gdb.so generated_offsets.py
+host_files = libpal-Linux-SGX.a pal-sgx debugger/sgx_gdb.so pal.map generated_offsets.py
 
 defs	= -DIN_PAL -DPAL_DIR=$(PAL_DIR) -DRUNTIME_DIR=$(RUNTIME_DIR)
 CFLAGS += $(defs)
diff --git a/Pal/src/host/Linux-SGX/Makefile.am b/Pal/src/host/Linux-SGX/Makefile.am
index 09d592e9..be4a2f4f 100644
--- a/Pal/src/host/Linux-SGX/Makefile.am
+++ b/Pal/src/host/Linux-SGX/Makefile.am
@@ -25,7 +25,7 @@ endif
 
 pal_loader = $(HOST_DIR)/pal-sgx
 pal_lib = $(HOST_DIR)/libpal.so
-pal_lib_deps = $(HOST_DIR)/enclave.lds $(HOST_DIR)/pal.map
+pal_lib_deps = pal-symbols $(HOST_DIR)/pal.map.template $(HOST_DIR)/enclave.lds
 pal_static = $(HOST_DIR)/libpal.a
 pal_gdb = $(HOST_DIR)/debugger/gdb
 pal_signer = pal-sgx-get-token pal-sgx-sign aesm_pb2.py
diff --git a/Pal/src/host/Linux-SGX/pal.map b/Pal/src/host/Linux-SGX/pal.map
deleted file mode 100644
index e20bcf18..00000000
--- a/Pal/src/host/Linux-SGX/pal.map
+++ /dev/null
@@ -1,51 +0,0 @@
-PAL {
-    global:
-        # Drawbridge ABIs
-        DkVirtualMemoryAlloc; DkVirtualMemoryFree; DkVirtualMemoryProtect;
-        DkThreadCreate; DkThreadDelayExecution;
-        DkThreadYieldExecution; DkThreadExit; DkThreadResume;
-
-        DkMutexCreate; DkNotificationEventCreate;
-        DkSynchronizationEventCreate;
-        DkMutexRelease;
-        DkEventSet;  DkEventClear;
-        DkObjectsWaitAny;
-
-        DkStreamOpen; DkStreamRead; DkStreamWrite;
-        DkStreamMap; DkStreamUnmap; DkStreamSetLength;
-        DkStreamFlush; DkStreamDelete;
-        DkSendHandle; DkReceiveHandle; # Added by us
-        DkStreamWaitForClient;
-        DkStreamGetName;
-        DkStreamAttributesQueryByHandle; DkStreamAttributesQuery;
-
-        DkProcessCreate; DkProcessExit;
-
-        DkSystemTimeQuery; DkRandomBitsRead;
-        DkInstructionCacheFlush;
-        DkObjectReference; DkObjectClose;
-        # objects checkpoint?
-        # objects reload?
-
-        # The ABIs we added in the paper
-        DkSetExceptionHandler; DkExceptionReturn; # exceptions
-        DkCreatePhysicalMemoryChannel; # IPC
-        DkPhysicalMemoryCommit; # IPC
-        DkPhysicalMemoryMap; # IPC
-        DkThreadStackSet; # set stack range
-        DkThreadPrivateSet; DkThreadPrivateGet; # set/get thread private area
-        DkThreadGetCurrent; # get a handle to describe the current thread
-        DkStreamChangeName;
-        DkStreamAttributesSetByHandle;
-        DkSegmentRegister; # set segment register
-        DkMemoryAvailableQuota;
-        DkCpuIdRetrieve; # retrieve CPUID
-
-        # Debugging ABIs
-        pal_printf; pal_snprintf; DkDebugAttachBinary; DkDebugDetachBinary;
-
-        # Control block
-        pal_control; pal_control_addr;
-
-    local: *;
-};
diff --git a/Pal/src/host/Linux-SGX/pal.map.template b/Pal/src/host/Linux-SGX/pal.map.template
new file mode 100644
index 00000000..54dd39c4
--- /dev/null
+++ b/Pal/src/host/Linux-SGX/pal.map.template
@@ -0,0 +1,4 @@
+PAL {
+    global: $(PAL_SYMBOLS)
+    local: *;
+};
diff --git a/Pal/src/host/Linux/Makefile b/Pal/src/host/Linux/Makefile
index 52b3950c..1b8334c0 100644
--- a/Pal/src/host/Linux/Makefile
+++ b/Pal/src/host/Linux/Makefile
@@ -10,7 +10,7 @@ ifeq ($(PROFILING),1)
 CFLAGS	+= -DPROFILING=1
 endif
 
-host_files = libpal-Linux.a
+host_files = libpal-Linux.a pal.map
 
 defs	= -DIN_PAL -DPAL_DIR=$(PAL_DIR) -DRUNTIME_DIR=$(RUNTIME_DIR)
 CFLAGS += $(defs)
@@ -51,7 +51,7 @@ include ../../../../Makefile.rules
 
 -include $(addsuffix .d,$(objs)) $(addsuffix .i.d,$(objs)) $(addsuffix .s.d,$(objs))
 
-CLEAN_FILES += $(notdir $(pal_static) $(pal_lib) $(pal_loader))
+CLEAN_FILES += $(notdir $(pal_static) $(pal_lib) $(pal_sec) $(pal_loader))
 
 .PHONY: clean
 clean:
diff --git a/Pal/src/host/Linux/Makefile.am b/Pal/src/host/Linux/Makefile.am
index b9241389..f400053c 100644
--- a/Pal/src/host/Linux/Makefile.am
+++ b/Pal/src/host/Linux/Makefile.am
@@ -22,7 +22,7 @@ endif
 
 pal_loader = $(HOST_DIR)/libpal.so
 pal_lib = $(HOST_DIR)/libpal.so
-pal_lib_deps = $(HOST_DIR)/pal.map $(HOST_DIR)/pal.lds
+pal_lib_deps = pal-symbols $(HOST_DIR)/pal.map.template $(HOST_DIR)/pal.lds
 pal_lib_post =
 pal_static = $(HOST_DIR)/libpal.a
 pal_gdb =
diff --git a/Pal/src/host/Linux/pal.map b/Pal/src/host/Linux/pal.map
deleted file mode 100644
index edcf7d25..00000000
--- a/Pal/src/host/Linux/pal.map
+++ /dev/null
@@ -1,55 +0,0 @@
-PAL {
-    global:
-        # Drawbridge ABIs
-        DkVirtualMemoryAlloc; DkVirtualMemoryFree; DkVirtualMemoryProtect;
-        DkThreadCreate; DkThreadDelayExecution;
-        DkThreadYieldExecution; DkThreadExit; DkThreadResume;
-
-        DkMutexCreate; DkNotificationEventCreate;
-        DkSynchronizationEventCreate;
-        DkMutexRelease;
-        DkEventSet;  DkEventClear;
-        DkObjectsWaitAny;
-
-        DkStreamOpen; DkStreamRead; DkStreamWrite;
-        DkStreamMap; DkStreamUnmap; DkStreamSetLength;
-        DkStreamFlush; DkStreamDelete;
-        DkSendHandle; DkReceiveHandle; # Added by us
-        DkStreamWaitForClient;
-        DkStreamGetName;
-        DkStreamAttributesQueryByHandle; DkStreamAttributesQuery;
-
-        DkProcessCreate; DkProcessExit;
-
-        DkSystemTimeQuery; DkRandomBitsRead;
-        DkInstructionCacheFlush;
-        DkCpuIdRetrieve;
-        DkObjectClose;
-        # objects checkpoint?
-        # objects reload?
-
-        # The ABIs we added in the paper
-        DkSetExceptionHandler; DkExceptionReturn; # exceptions
-        DkCreatePhysicalMemoryChannel; # IPC
-        DkPhysicalMemoryCommit; # IPC
-        DkPhysicalMemoryMap; # IPC
-        DkSegmentRegister; # set segmentation registers
-        DkStreamChangeName;
-        DkStreamAttributesSetByHandle;
-        DkMemoryAvailableQuota;
-
-        # Debugging ABIs
-        pal_printf; DkDebugAttachBinary; DkDebugDetachBinary;
-
-        # Control block
-        pal_control_addr; pal_sec;
-
-        # debugger
-        _r_debug;
-
-    local: *;
-};
-PAL_PRIVATE {
-    global:
-        _dl_debug_state;
-};
diff --git a/Pal/src/host/Linux/pal.map.template b/Pal/src/host/Linux/pal.map.template
new file mode 100644
index 00000000..b8d5c3a2
--- /dev/null
+++ b/Pal/src/host/Linux/pal.map.template
@@ -0,0 +1,9 @@
+PAL {
+    global: $(PAL_SYMBOLS) _r_debug;
+
+    local: *;
+};
+PAL_PRIVATE {
+    global:
+        _dl_debug_state;
+};
diff --git a/Pal/src/host/Skeleton/Makefile b/Pal/src/host/Skeleton/Makefile
index 1c1e59c4..8adfe949 100644
--- a/Pal/src/host/Skeleton/Makefile
+++ b/Pal/src/host/Skeleton/Makefile
@@ -4,18 +4,17 @@ include Makefile.am
 CFLAGS  += -I. -I../.. -I../../../include -I../../../lib
 ASFLAGS += -I. -I../.. -I../../../include
 
-host_target = libpal-Skeleton.a
+host_files = libpal-Skeleton.a pal.map
 
 defs	= -DIN_PAL
 CFLAGS += $(defs)
 ASFLAGS += $(defs)
 objs	= $(addprefix db_,files devices pipes sockets streams memory threading \
-	    semaphore events process object main rtld misc ipc exception)
-graphene_lib = ../../../lib/graphene-lib.a
+	    mutex events process object main rtld misc ipc exception)
 headers	= $(wildcard *.h) $(wildcard ../../*.h) $(wildcard ../../../lib/*.h)
 
 .PHONY: all
-all: $(host_target)
+all: $(host_files)
 
 ifeq ($(DEBUG),1)
 CC += -gdwarf-2 -g3
@@ -26,7 +25,7 @@ endif
 ../../host_endian.h: host_endian.h
 	$(MAKE) -C ../../ $<
 
-libpal-Skeleton.a: $(addsuffix .o,$(objs)) $(graphene_lib)
+libpal-Skeleton.a: $(addsuffix .o,$(objs))
 	$(call cmd,ar_a_o)
 
 %.o: %.c $(headers)
@@ -39,4 +38,4 @@ include ../../../../Makefile.rules
 
 .PHONY: clean
 clean:
-	rm -f $(addsuffix .o,$(objs)) $(host_target)
+	rm -f $(addsuffix .o,$(objs)) $(host_files)
diff --git a/Pal/src/host/Skeleton/Makefile.am b/Pal/src/host/Skeleton/Makefile.am
index 267877e9..58a0be46 100644
--- a/Pal/src/host/Skeleton/Makefile.am
+++ b/Pal/src/host/Skeleton/Makefile.am
@@ -1,9 +1,26 @@
 # Add host-specific compilation rules here
 
-CFLAGS  = -Wall -fPIC -O2 -std=gnu99 -fgnu89-inline -Wall -U_FORTIFY_SOURCE -fno-builtin
-ASFLAGS = -DPIC -DSHARED -fPIC -DASSEMBLER -Wa,--noexecstack -x assembler-with-cpp
+CFLAGS = -Wall -fPIC -O2 -std=c11 -U_FORTIFY_SOURCE \
+         -fno-stack-protector -fno-builtin
+
+EXTRAFLAGS = -Wextra -Wno-unused-parameter -Wno-sign-compare $(call cc-option,-Wnull-dereference)
+
+CFLAGS += $(EXTRAFLAGS)
+
+ASFLAGS = -DPIC -DSHARED -fPIC -DASSEMBLER -Wa,--noexecstack \
+	  -x assembler-with-cpp
+LDFLAGS = -shared -nostdlib -z combreloc -z defs \
+	  --version-script $(HOST_DIR)/pal.map -T $(HOST_DIR)/pal.lds
 ARFLAGS =
 
 ifeq ($(WERROR),1)
 CFLAGS += -Werror
 endif
+
+pal_loader =
+pal_sec =
+pal_lib = $(HOST_DIR)/libpal.so
+pal_lib_deps = pal-symbols $(HOST_DIR)/pal.map.template $(HOST_DIR)/pal.lds
+pal_lib_post =
+pal_static =
+pal_gdb =
diff --git a/Pal/src/host/Skeleton/db_devices.c b/Pal/src/host/Skeleton/db_devices.c
index 4c346932..187682df 100644
--- a/Pal/src/host/Skeleton/db_devices.c
+++ b/Pal/src/host/Skeleton/db_devices.c
@@ -204,7 +204,7 @@ static int dev_attrquery (const char * type, const char * uri,
                           PAL_STREAM_ATTR * attr)
 {
     struct handle_ops * ops = NULL;
-    const char * dev_type = NULL;
+    char * dev_type = NULL;
     int ret = 0;
 
     ret = parse_device_uri(&uri, &dev_type, &ops);
diff --git a/Pal/src/host/Skeleton/db_events.c b/Pal/src/host/Skeleton/db_events.c
index 71ac9630..e67da757 100644
--- a/Pal/src/host/Skeleton/db_events.c
+++ b/Pal/src/host/Skeleton/db_events.c
@@ -41,7 +41,7 @@ int _DkEventSet (PAL_HANDLE event, int wakeup)
     return -PAL_ERROR_NOTIMPLEMENTED;
 }
 
-int _DkEventWaitTimeout (PAL_HANDLE event, uint64_t timeout)
+int _DkEventWaitTimeout (PAL_HANDLE event, int64_t timeout_us)
 {
     return -PAL_ERROR_NOTIMPLEMENTED;
 }
@@ -55,3 +55,18 @@ int _DkEventClear (PAL_HANDLE event)
 {
     return -PAL_ERROR_NOTIMPLEMENTED;
 }
+
+static int event_close (PAL_HANDLE handle)
+{
+    return -PAL_ERROR_NOTIMPLEMENTED;
+}
+
+static int event_wait (PAL_HANDLE handle, int64_t timeout_us)
+{
+    return -PAL_ERROR_NOTIMPLEMENTED;
+}
+
+struct handle_ops event_ops = {
+        .close              = &event_close,
+        .wait               = &event_wait,
+    };
diff --git a/Pal/src/host/Skeleton/db_files.c b/Pal/src/host/Skeleton/db_files.c
index 98f202dd..2a465361 100644
--- a/Pal/src/host/Skeleton/db_files.c
+++ b/Pal/src/host/Skeleton/db_files.c
@@ -102,7 +102,7 @@ static int file_rename (PAL_HANDLE handle, const char * type,
     return -PAL_ERROR_NOTIMPLEMENTED;
 }
 
-static int file_getname (PAL_HANDLE handle, char * buffer, int count)
+static int file_getname (PAL_HANDLE handle, char * buffer, size_t count)
 {
     return -PAL_ERROR_NOTIMPLEMENTED;
 }
@@ -169,7 +169,7 @@ static int dir_rename (PAL_HANDLE handle, const char * type,
     return -PAL_ERROR_NOTIMPLEMENTED;
 }
 
-static int dir_getname (PAL_HANDLE handle, char * buffer, int count)
+static int dir_getname (PAL_HANDLE handle, char * buffer, size_t count)
 {
     return -PAL_ERROR_NOTIMPLEMENTED;
 }
diff --git a/Pal/src/host/Skeleton/db_main.c b/Pal/src/host/Skeleton/db_main.c
index d9c3d424..d865ecb7 100644
--- a/Pal/src/host/Skeleton/db_main.c
+++ b/Pal/src/host/Skeleton/db_main.c
@@ -60,7 +60,8 @@ PAL_NUM _DkGetHostId (void)
     return 0;
 }
 
-void _DkGetCPUInfo (PAL_CPU_INFO * ci)
+int _DkGetCPUInfo (PAL_CPU_INFO * ci)
 {
     /* need to be implemented */
+    return 0;
 }
diff --git a/Pal/src/host/Skeleton/db_misc.c b/Pal/src/host/Skeleton/db_misc.c
index 495e9170..ba808c51 100644
--- a/Pal/src/host/Skeleton/db_misc.c
+++ b/Pal/src/host/Skeleton/db_misc.c
@@ -41,7 +41,7 @@ unsigned long _DkSystemTimeQuery (void)
     return 0;
 }
 
-int _DkRandomBitsRead (void * buffer, int size)
+size_t _DkRandomBitsRead (void * buffer, size_t size)
 {
     return -PAL_ERROR_NOTIMPLEMENTED;
 }
@@ -60,3 +60,9 @@ int _DkInstructionCacheFlush (const void * addr, int size)
 {
     return -PAL_ERROR_NOTIMPLEMENTED;
 }
+
+int _DkCpuIdRetrieve (unsigned int leaf, unsigned int subleaf,
+                      unsigned int values[4])
+{
+    return -PAL_ERROR_NOTIMPLEMENTED;
+}
diff --git a/Pal/src/host/Skeleton/db_semaphore.c b/Pal/src/host/Skeleton/db_mutex.c
similarity index 63%
rename from Pal/src/host/Skeleton/db_semaphore.c
rename to Pal/src/host/Skeleton/db_mutex.c
index 002b35e6..1c14ccf8 100644
--- a/Pal/src/host/Skeleton/db_semaphore.c
+++ b/Pal/src/host/Skeleton/db_mutex.c
@@ -15,9 +15,7 @@
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
 /*
- * db_semaphore.c
- *
- * This file contains APIs that provides operations of semaphores.
+ * db_mutex.c
  */
 
 #include "api.h"
@@ -26,26 +24,42 @@
 #include "pal_error.h"
 #include "pal_internal.h"
 
-int _DkSemaphoreCreate(PAL_HANDLE handle, int initialCount, int maxCount) {
+int
+_DkMutexCreate (PAL_HANDLE * handle, int initialCount)
+{
     return -PAL_ERROR_NOTIMPLEMENTED;
 }
 
-void _DkSemaphoreDestroy(PAL_HANDLE semaphoreHandle) {
-    /* need to be implemented */
-}
-
-int _DkSemaphoreAcquire(PAL_HANDLE sem, int count) {
+int _DkMutexLockTimeout (struct mutex_handle * m, int64_t timeout_us)
+{
     return -PAL_ERROR_NOTIMPLEMENTED;
 }
 
-int _DkSemaphoreAcquireTimeout(PAL_HANDLE sem, int count, int timeout) {
+int _DkMutexLock (struct mutex_handle * m)
+{
     return -PAL_ERROR_NOTIMPLEMENTED;
 }
 
-void _DkSemaphoreRelease(PAL_HANDLE sem, int count) {
-    /* need to be implemented */
-}
-
-int _DkSemaphoreGetCurrentCount(PAL_HANDLE sem) {
+int _DkMutexAcquireTimeout (PAL_HANDLE handle, int64_t timeout_us)
+{
     return -PAL_ERROR_NOTIMPLEMENTED;
 }
+
+int _DkMutexUnlock (struct mutex_handle * m)
+{
+    return -PAL_ERROR_NOTIMPLEMENTED;
+}
+
+void _DkMutexRelease (PAL_HANDLE handle)
+{
+    /* Not implemented yet */
+}
+
+static int mutex_wait (PAL_HANDLE handle, int64_t timeout_us)
+{
+    return -PAL_ERROR_NOTIMPLEMENTED;
+}
+
+struct handle_ops mutex_ops = {
+        .wait               = &mutex_wait,
+    };
diff --git a/Pal/src/host/Skeleton/db_object.c b/Pal/src/host/Skeleton/db_object.c
index 68dce42a..8e92cb27 100644
--- a/Pal/src/host/Skeleton/db_object.c
+++ b/Pal/src/host/Skeleton/db_object.c
@@ -29,6 +29,6 @@
 
 /* _DkObjectsWaitAny for internal use. The function wait for any of the handle
    in the handle array. timeout can be set for the wait. */
-int _DkObjectsWaitAny(int count, PAL_HANDLE* handleArray, uint64_t timeout, PAL_HANDLE* polled) {
+int _DkObjectsWaitAny(int count, PAL_HANDLE* handleArray, int64_t timeout_us, PAL_HANDLE* polled) {
     return -PAL_ERROR_NOTIMPLEMENTED;
 }
diff --git a/Pal/src/host/Skeleton/db_pipes.c b/Pal/src/host/Skeleton/db_pipes.c
index d797888e..0bb8e5b0 100644
--- a/Pal/src/host/Skeleton/db_pipes.c
+++ b/Pal/src/host/Skeleton/db_pipes.c
@@ -109,7 +109,7 @@ static int pipe_delete (PAL_HANDLE handle, int access)
     return -PAL_ERROR_NOTIMPLEMENTED;
 }
 
-static int pipe_getname (PAL_HANDLE handle, char * buffer, int count)
+static int pipe_getname (PAL_HANDLE handle, char * buffer, size_t count)
 {
     return -PAL_ERROR_NOTIMPLEMENTED;
 }
diff --git a/Pal/src/host/Skeleton/db_process.c b/Pal/src/host/Skeleton/db_process.c
index a2e8afe8..a356e6ab 100644
--- a/Pal/src/host/Skeleton/db_process.c
+++ b/Pal/src/host/Skeleton/db_process.c
@@ -32,15 +32,16 @@
 #include "pal_error.h"
 #include "api.h"
 
-int _DkProcessCreate (PAL_HANDLE * handle, const char * uri,
-                      int flags, const char ** args)
+int _DkProcessCreate (PAL_HANDLE * handle, const char * uri, const char ** args)
 {
     return -PAL_ERROR_NOTIMPLEMENTED;
 }
 
 noreturn void _DkProcessExit (int exitcode)
 {
-    /* need to be implemented */
+    while (true) {
+        /* nothing */;
+    }
 }
 
 static int64_t proc_read (PAL_HANDLE handle, uint64_t offset, uint64_t count,
diff --git a/Pal/src/host/Skeleton/db_sockets.c b/Pal/src/host/Skeleton/db_sockets.c
index e7ab6e8c..b4563348 100644
--- a/Pal/src/host/Skeleton/db_sockets.c
+++ b/Pal/src/host/Skeleton/db_sockets.c
@@ -54,7 +54,7 @@ static int tcp_connect (PAL_HANDLE * handle, char * uri, int create)
 static int tcp_open (PAL_HANDLE *handle, const char * type, const char * uri,
                      int access, int share, int create, int options)
 {
-    int uri_len = strlen(uri) + 1;
+    size_t uri_len = strlen(uri) + 1;
 
     if (uri_len > PAL_SOCKADDR_SIZE)
         return -PAL_ERROR_TOOLONG;
@@ -72,13 +72,13 @@ static int tcp_open (PAL_HANDLE *handle, const char * type, const char * uri,
 }
 
 /* 'read' operation of tcp stream */
-static int64_t tcp_read (PAL_HANDLE handle, uint64_t offset, uint64_t len, void * buf)
+static int64_t tcp_read (PAL_HANDLE handle, uint64_t offset, size_t len, void * buf)
 {
     return -PAL_ERROR_NOTIMPLEMENTED;
 }
 
 /* write' operation of tcp stream */
-static int64_t tcp_write (PAL_HANDLE handle, uint64_t offset, uint64_t len, const void * buf)
+static int64_t tcp_write (PAL_HANDLE handle, uint64_t offset, size_t len, const void * buf)
 {
     return -PAL_ERROR_NOTIMPLEMENTED;
 }
@@ -99,7 +99,7 @@ static int udp_open (PAL_HANDLE *hdl, const char * type, const char * uri,
                      int access, int share, int create, int options)
 {
     char buf[PAL_SOCKADDR_SIZE];
-    int len = strlen(uri);
+    size_t len = strlen(uri);
 
     if (len >= PAL_SOCKADDR_SIZE)
         return -PAL_ERROR_TOOLONG;
@@ -115,24 +115,24 @@ static int udp_open (PAL_HANDLE *hdl, const char * type, const char * uri,
     return -PAL_ERROR_NOTSUPPORT;
 }
 
-static int64_t udp_receive (PAL_HANDLE handle, uint64_t offset, uint64_t len, void * buf)
+static int64_t udp_receive (PAL_HANDLE handle, uint64_t offset, size_t len, void * buf)
 {
     return -PAL_ERROR_NOTIMPLEMENTED;
 }
 
-static int64_t udp_receivebyaddr (PAL_HANDLE handle, uint64_t offset, uint64_t len,
-                              void * buf, char * addr, int addrlen)
+static int64_t udp_receivebyaddr (PAL_HANDLE handle, uint64_t offset, size_t len,
+                              void * buf, char * addr, size_t addrlen)
 {
     return -PAL_ERROR_NOTIMPLEMENTED;
 }
 
-static int64_t udp_send (PAL_HANDLE handle, uint64_t offset, uint64_t len, const void * buf)
+static int64_t udp_send (PAL_HANDLE handle, uint64_t offset, size_t len, const void * buf)
 {
     return -PAL_ERROR_NOTIMPLEMENTED;
 }
 
-static int64_t udp_sendbyaddr (PAL_HANDLE handle, uint64_t offset, uint64_t len,
-                               const void * buf, const char * addr, int addrlen)
+static int64_t udp_sendbyaddr (PAL_HANDLE handle, uint64_t offset, size_t len,
+                               const void * buf, const char * addr, size_t addrlen)
 {
     return -PAL_ERROR_NOTIMPLEMENTED;
 }
@@ -152,7 +152,7 @@ static int socket_attrquerybyhdl (PAL_HANDLE handle, PAL_STREAM_ATTR  * attr)
     return -PAL_ERROR_NOTIMPLEMENTED;
 }
 
-static int socket_getname (PAL_HANDLE handle, char * buffer, int count)
+static int socket_getname (PAL_HANDLE handle, char * buffer, size_t count)
 {
     return -PAL_ERROR_NOTIMPLEMENTED;
 }
diff --git a/Pal/src/host/Skeleton/pal.lds b/Pal/src/host/Skeleton/pal.lds
new file mode 100644
index 00000000..93d87516
--- /dev/null
+++ b/Pal/src/host/Skeleton/pal.lds
@@ -0,0 +1,82 @@
+OUTPUT_FORMAT("elf64-x86-64", "elf64-x86-64", "elf64-x86-64")
+OUTPUT_ARCH(i386:x86-64)
+ENTRY(pal_start);
+
+SECTIONS
+{
+  /* Read-only sections, merged into text segment; */
+  __text_start = .;
+  . = SEGMENT_START("text-segment", 0) + SIZEOF_HEADERS;
+  .note.gnu.build-id : { *(.note.gnu.build-id) }
+  .hash          : { *(.hash) }
+  .gnu.hash      : { *(.gnu.hash) }
+  .dynsym        : { *(.dynsym) }
+  .dynstr        : { *(.dynstr) }
+  .gnu.version   : { *(.gnu.version) }
+  .gnu.version_d : { *(.gnu.version_d) }
+  .gnu.version_r : { *(.gnu.version_r) }
+  .rela.dyn       :
+     {
+      *(.rela.init)
+      *(.rela.text .rela.text.* .rela.gnu.linkonce.t.*)
+      *(.rela.fini)
+      *(.rela.rodata .rela.rodata.* .rela.gnu.linkonce.r.*)
+      *(.rela.data .rela.data.* .rela.gnu.linkonce.d.*)
+      *(.rela.tdata .rela.tdata.* .rela.gnu.linkonce.td.*)
+      *(.rela.tbss .rela.tbss.* .rela.gnu.linkonce.tb.*)
+      *(.rela.ctors)
+      *(.rela.dtors)
+      *(.rela.got)
+      *(.rela.bss .rela.bss.* .rela.gnu.linkonce.b.*)
+      *(.rela.ldata .rela.ldata.* .rela.gnu.linkonce.l.*)
+      *(.rela.lbss .rela.lbss.* .rela.gnu.linkonce.lb.*)
+      *(.rela.lrodata .rela.lrodata.* .rela.gnu.linkonce.lr.*)
+      *(.rela.ifunc)
+    }
+  .rela.plt      :
+    {
+      *(.rela.plt)
+      *(.rela.iplt)
+    }
+  .init          : { *(.init) }
+  .plt           : { *(.plt) *(.iplt) }
+  .text :
+  {
+    /* the rest of text segments */
+    *(.text .stub .text.*);
+  }
+  .fini          : { *(.fini) }
+  .rodata        :
+  {
+    /* the rest of rodata */
+    *(.rodata .rodata.*)
+  }
+  .eh_frame_hdr  : { *(.eh_frame_hdr) }
+  .eh_frame      : ONLY_IF_RO { *(.eh_frame) }
+  __text_end = .;
+
+  /* now adjust the address for the data segment */
+  . = DATA_SEGMENT_ALIGN (CONSTANT (MAXPAGESIZE), CONSTANT (COMMONPAGESIZE));
+  __data_start = .;
+  .eh_frame      : ONLY_IF_RW { *(.eh_frame) }
+  .data.rel.ro   : { *(.data.rel.ro) }
+  .ctors         : { *(.ctors) }
+  .dtors         : { *(.dtors) }
+  .jcr           : { *(.jcr) }
+  .dynamic       : { *(.dynamic) }
+  .got           : { *(.got) *(.igot) }
+  .got.plt       : { *(.got.plt) *(.igot.plt) }
+  .data :
+  {
+    /* the rest of data segment */
+    *(.data .data.*);
+  }
+  .bss            :
+  {
+    *(.bss .bss.*)
+    *(COMMON)
+  }
+  . = DATA_SEGMENT_END(.);
+  __data_end = .;
+}
+
diff --git a/Pal/src/host/Skeleton/pal.map b/Pal/src/host/Skeleton/pal.map
deleted file mode 100644
index 266e1955..00000000
--- a/Pal/src/host/Skeleton/pal.map
+++ /dev/null
@@ -1,54 +0,0 @@
-PAL {
-    global:
-        # Drawbridge ABIs
-        DkVirtualMemoryAlloc; DkVirtualMemoryFree; DkVirtualMemoryProtect;
-        DkThreadCreate; DkThreadDelayExecution;
-        DkThreadYieldExecution; DkThreadExit; DkThreadResume;
-
-        DkSemaphoreCreate; DkNotificationEventCreate;
-        DkSynchronizationEventCreate;
-        DkSemaphoreRelease;
-        DkEventSet;  DkEventClear;
-        DkObjectsWaitAny;
-
-        DkStreamOpen; DkStreamRead; DkStreamWrite;
-        DkStreamMap; DkStreamUnmap; DkStreamSetLength;
-        DkStreamFlush; DkStreamDelete;
-        DkSendHandle; DkReceiveHandle; # Added by us
-        DkStreamWaitForClient;
-        DkStreamGetName;
-        DkStreamAttributesQueryByHandle; DkStreamAttributesQuery;
-
-        DkProcessCreate; DkProcessExit;
-
-        DkSystemTimeQuery; DkRandomBitsRead;
-        DkInstructionCacheFlush;
-        DkObjectReference; DkObjectClose;
-        # objects checkpoint?
-        # objects reload?
-
-        # The ABIs we added in the paper
-        DkSetExceptionHandler; DkExceptionReturn; # exceptions
-        DkCreatePhysicalMemoryChannel; # IPC
-        DkPhysicalMemoryCommit; # IPC
-        DkPhysicalMemoryMap; # IPC
-        DkSegmentRegister; # set segmentation registers
-        DkStreamChangeName;
-        DkStreamAttributesSetByHandle;
-        DkMemoryAvailableQuota;
-
-        # Debugging ABIs
-        pal_printf; DkDebugAttachBinary; DkDebugDetachBinary;
-
-        # Control block
-        pal_control_addr; pal_sec;
-
-        # debugger interface
-        _r_debug;
-
-    local: *;
-};
-PAL_PRIVATE {
-    global:
-        _dl_debug_state;
-};
diff --git a/Pal/src/host/Skeleton/pal.map.template b/Pal/src/host/Skeleton/pal.map.template
new file mode 100644
index 00000000..54dd39c4
--- /dev/null
+++ b/Pal/src/host/Skeleton/pal.map.template
@@ -0,0 +1,4 @@
+PAL {
+    global: $(PAL_SYMBOLS)
+    local: *;
+};
diff --git a/Pal/src/host/Skeleton/pal_host.h b/Pal/src/host/Skeleton/pal_host.h
index d9e2f2da..cebacd4f 100644
--- a/Pal/src/host/Skeleton/pal_host.h
+++ b/Pal/src/host/Skeleton/pal_host.h
@@ -27,8 +27,13 @@
 # error "cannot be included outside PAL"
 #endif
 
-typedef int PAL_LOCK;
-#define LOCK_INIT   0
+typedef struct mutex_handle {
+    int unused;
+} PAL_LOCK;
+
+#define LOCK_INIT   {}
+#define INIT_LOCK(lock) do {} while (0)
+
 #define MAX_FDS     3
 
 typedef struct pal_handle
@@ -79,20 +84,20 @@ typedef struct pal_handle
         } sock;
 
         struct {
-            PAL_IDX fd;
+            PAL_IDX unused;
         } process;
 
         struct {
-            PAL_IDX fd;
+            PAL_IDX unused;
         } mcast;
 
         struct {
-            PAL_IDX fd;
+            PAL_IDX unused;
         } thread;
 
         struct {
             PAL_IDX fd;
-        } semaphore;
+        } mutex;
 
         struct {
             PAL_IDX fd;
diff --git a/Pal/src/pal-symbols b/Pal/src/pal-symbols
new file mode 100644
index 00000000..112c7deb
--- /dev/null
+++ b/Pal/src/pal-symbols
@@ -0,0 +1,50 @@
+DkVirtualMemoryAlloc
+DkVirtualMemoryFree
+DkVirtualMemoryProtect
+DkThreadCreate
+DkThreadDelayExecution
+DkThreadYieldExecution
+DkThreadExit
+DkThreadResume
+DkMutexCreate
+DkNotificationEventCreate
+DkSynchronizationEventCreate
+DkMutexRelease
+DkEventSet
+DkEventClear
+DkObjectsWaitAny
+DkStreamOpen
+DkStreamRead
+DkStreamWrite
+DkStreamMap
+DkStreamUnmap
+DkStreamSetLength
+DkStreamFlush
+DkStreamDelete
+DkSendHandle
+DkReceiveHandle
+DkStreamWaitForClient
+DkStreamGetName
+DkStreamAttributesQueryByHandle
+DkStreamAttributesQuery
+DkProcessCreate
+DkProcessExit
+DkProcessSandboxCreate
+DkSystemTimeQuery
+DkRandomBitsRead
+DkInstructionCacheFlush
+DkCpuIdRetrieve
+DkObjectClose
+DkSetExceptionHandler
+DkExceptionReturn
+DkCreatePhysicalMemoryChannel
+DkPhysicalMemoryCommit
+DkPhysicalMemoryMap
+DkSegmentRegister
+DkStreamChangeName
+DkStreamAttributesSetByHandle
+DkMemoryAvailableQuota
+DkDebugAttachBinary
+DkDebugDetachBinary
+pal_printf
+pal_control_addr