diff --git a/Ubiquitous/XiZi_AIoT/README.md b/Ubiquitous/XiZi_AIoT/README.md
index daf4cd253..caefb9738 100755
--- a/Ubiquitous/XiZi_AIoT/README.md
+++ b/Ubiquitous/XiZi_AIoT/README.md
@@ -1,2 +1,22 @@
-# XIZI_AIOT
+### XiZi_AIoT Microkernel
 
+XiZi_AIoT is a microkernel designed to facilitate task management, memory management, IPC, and various userland sample applications.
+
+### Building Instructions
+
+To build the XiZi_AIoT microkernel, navigate to the directory xiuos/Ubiquitous/XiZi_AIoT and run the command `make BOARD=$(BOARD)`. By default, running `make` is equivalent to `make BOARD=imx6q-sabrelite`. For building XiZi_AIoT specifically for the imx6q-sabrelite board, you'll need the gcc-arm-none-eabi toolchain. We recommend using version "arm-none-eabi-gcc (GNU Tools for ARM Embedded Processors 6-2017-q1-update) 6.3.1 20170215 (release)", as this version was used during development. If the build process is successful, the generated files can be found in the "build" directory. Use either XiZi-$(BOARD).elf or XiZi-$(BOARD).bin as the image to run on the board or QEMU.
+
+### Running on QEMU
+
+QEMU is a useful tool for emulating boards while testing or developing XiZi_AIoT. Use the following command:
+
+```
+qemu-system-arm -M sabrelite -m 1G -smp 4 -cpu cortex-a9 \
+    -display none -serial null -serial stdio \
+    -kernel xiuos/Ubiquitous/XiZi_AIoT/build/XiZi-imx6q-sabrelite.elf
+```
+Replace "xiuos/Ubiquitous/XiZi_AIoT/build/XiZi-imx6q-sabrelite.elf" with the appropriate path in your directory. We recommend using version "QEMU emulator version 7.2.0" for successful emulation of the sabrelite board.
+
+### Makefile Usage
+
+XiZi_AIoT utilizes a Makefile to build all its files, including .c and .S files. The compiler.mk file enables the make tool to iterate through all sub-directories defined by *SRC_DIR* and compile files defined by *SRC_FILES* using parameters defined in config.mk. Each board independently defines its config.mk file in hardkernel/arch/.../config.mk. Additionally, path_kernel.mk defines all include paths needed by XiZi_AIoT, and link.mk manages the linking process after all .c and .S files are compiled.
\ No newline at end of file
diff --git a/Ubiquitous/XiZi_AIoT/services/app/Makefile b/Ubiquitous/XiZi_AIoT/services/app/Makefile
index f564e4008..0fdf53553 100644
--- a/Ubiquitous/XiZi_AIoT/services/app/Makefile
+++ b/Ubiquitous/XiZi_AIoT/services/app/Makefile
@@ -26,7 +26,7 @@ INC_DIR = 	-I$(KERNEL_ROOT)/services/shell/letter-shell \
 			-I$(KERNEL_ROOT)/services/app 
 
 ifeq ($(BOARD), imx6q-sabrelite)
-all: init test_fs simple_client simple_server shell fs_server test_irq_hdlr test_irq_block test_irq_send eth_driver timer_server readme.txt | bin
+all: init test_fs simple_client simple_server shell fs_server test_irq_hdlr test_irq_block test_irq_send eth_driver epit_server readme.txt | bin
 else 
 all: init test_fs simple_client simple_server shell fs_server test_irq_hdlr readme.txt | bin
 endif
@@ -47,7 +47,7 @@ eth_driver: enet_drv.o enet_test.o board_network.o enet_iomux_config.o imx6dq_gp
 	@${ld} ${user_ldflags} -e main -o $@ $^ ${board_specs}
 	@${objdump} -S $@ > $@.asm
 
-timer_server: timer.o epit.o ccm_pll.o usyscall.o arch_usyscall.o libserial.o printf.o libipc.o session.o
+epit_server: timer.o epit.o ccm_pll.o usyscall.o arch_usyscall.o libserial.o printf.o libipc.o session.o
 	@${ld} ${user_ldflags} -e main -o $@ $^ ${board_specs}
 	@${objdump} -S $@ > $@.asm
 endif
diff --git a/Ubiquitous/XiZi_AIoT/services/app/init.c b/Ubiquitous/XiZi_AIoT/services/app/init.c
index 3c3fc1446..d204ca4a8 100755
--- a/Ubiquitous/XiZi_AIoT/services/app/init.c
+++ b/Ubiquitous/XiZi_AIoT/services/app/init.c
@@ -28,7 +28,7 @@ int main(int argc, char* argv[])
     char* shell_task_param[2] = { "/shell", 0 };
     if ((fd = open(&session, shell_task_param[0])) < 0) {
         printf("Open %s failed\n", shell_task_param[0]);
-        exit();
+        exit(1);
     }
 
     if (spawn(&session, fd, read, fsize, shell_task_param[0], shell_task_param) < 0) {
@@ -37,6 +37,6 @@ int main(int argc, char* argv[])
 
     close(&session, fd);
 
-    exit();
+    exit(0);
     return 0;
 }
diff --git a/Ubiquitous/XiZi_AIoT/services/app/simple_client.c b/Ubiquitous/XiZi_AIoT/services/app/simple_client.c
index 0462bce7d..8df8064a1 100755
--- a/Ubiquitous/XiZi_AIoT/services/app/simple_client.c
+++ b/Ubiquitous/XiZi_AIoT/services/app/simple_client.c
@@ -12,6 +12,7 @@
 #include <assert.h>
 #include <stdbool.h>
 #include <stdint.h>
+#include <stdlib.h>
 
 #include "libfs_to_client.h"
 #include "libserial.h"
@@ -90,7 +91,7 @@ int main(int argc, char** argv)
     struct Session session_nowait;
     if (connect_session(&session_wait, "SimpleServer", 4096) < 0 || connect_session(&session_nowait, "SimpleServer", 4096) < 0) {
         printf("connect session failed\n");
-        exit();
+        exit(1);
     }
 
     char *buf1 = NULL, *buf2 = NULL;
@@ -138,5 +139,5 @@ int main(int argc, char** argv)
     free_session(&session_wait);
     free_session(&session_nowait);
 
-    exit();
+    exit(0);
 }
diff --git a/Ubiquitous/XiZi_AIoT/services/app/simple_server.c b/Ubiquitous/XiZi_AIoT/services/app/simple_server.c
index 90cb8e442..0a2ba417c 100755
--- a/Ubiquitous/XiZi_AIoT/services/app/simple_server.c
+++ b/Ubiquitous/XiZi_AIoT/services/app/simple_server.c
@@ -38,10 +38,10 @@ int main(int argc, char* argv[])
 {
     if (register_server("SimpleServer") < 0) {
         printf("register server name: %s failed.\n", "SimpleServer");
-        exit();
+        exit(1);
     }
     ipc_server_loop(&IpcSimpleServer);
 
     // never reached
-    exit();
+    exit(0);
 }
diff --git a/Ubiquitous/XiZi_AIoT/services/app/test_fs.c b/Ubiquitous/XiZi_AIoT/services/app/test_fs.c
index 3e592530f..c6f2e5f95 100644
--- a/Ubiquitous/XiZi_AIoT/services/app/test_fs.c
+++ b/Ubiquitous/XiZi_AIoT/services/app/test_fs.c
@@ -48,6 +48,6 @@ int main(int argc, char* argv[])
     printf("Test memry error %s.\n", 0x50000000);
     printf("After error computing.\n");
 
-    exit();
+    exit(0);
     return 0;
 }
diff --git a/Ubiquitous/XiZi_AIoT/services/app/test_irq_block.c b/Ubiquitous/XiZi_AIoT/services/app/test_irq_block.c
index 0fb246e80..d4a715379 100644
--- a/Ubiquitous/XiZi_AIoT/services/app/test_irq_block.c
+++ b/Ubiquitous/XiZi_AIoT/services/app/test_irq_block.c
@@ -24,12 +24,12 @@ int main(int argc, char* argv[])
     struct Session session;
     if (connect_session(&session, "TestIRQ", 4096) < 0) {
         printf("connect session failed\n");
-        exit();
+        exit(1);
     }
 
     printf("%s start waiting for IRQ.\n", prog_name);
     wait_intr(&session);
     printf("%s return from waiting for IRQ.\n", prog_name);
 
-    exit();
+    exit(0);
 }
\ No newline at end of file
diff --git a/Ubiquitous/XiZi_AIoT/services/app/test_irq_handler.c b/Ubiquitous/XiZi_AIoT/services/app/test_irq_handler.c
index c1f49fb0c..60e97b726 100644
--- a/Ubiquitous/XiZi_AIoT/services/app/test_irq_handler.c
+++ b/Ubiquitous/XiZi_AIoT/services/app/test_irq_handler.c
@@ -40,16 +40,16 @@ int main()
 {
     if (register_irq(SW_INTERRUPT_3, Ipc_intr_3) < 0) {
         printf("TEST_SW_HDLR: bind failed");
-        exit();
+        exit(1);
     }
 
     static char prog_name[] = "TestIRQ";
     if (register_server("TestIRQ") < 0) {
         printf("register server name: %s failed.\n", prog_name);
-        exit();
+        exit(1);
     }
 
     ipc_server_loop(&IpcSwIntrHandler);
 
-    exit();
+    exit(0);
 }
\ No newline at end of file
diff --git a/Ubiquitous/XiZi_AIoT/services/app/test_priority.c b/Ubiquitous/XiZi_AIoT/services/app/test_priority.c
index 6bd1c15f1..cefa2a48e 100644
--- a/Ubiquitous/XiZi_AIoT/services/app/test_priority.c
+++ b/Ubiquitous/XiZi_AIoT/services/app/test_priority.c
@@ -39,6 +39,6 @@ int main(int argc, char* argv[])
     // test function
     count_down();
 
-    exit();
+    exit(0);
     return 0;
 }
diff --git a/Ubiquitous/XiZi_AIoT/services/boards/imx6q-sabrelite/test_irq_sender.c b/Ubiquitous/XiZi_AIoT/services/boards/imx6q-sabrelite/test_irq_sender.c
index c3eb4328f..566d5add6 100644
--- a/Ubiquitous/XiZi_AIoT/services/boards/imx6q-sabrelite/test_irq_sender.c
+++ b/Ubiquitous/XiZi_AIoT/services/boards/imx6q-sabrelite/test_irq_sender.c
@@ -96,5 +96,5 @@ int main()
         printf("%s: Soft interrupt send 1 time\n", prog_name);
     }
     printf("%s: Soft interrupt send done\n", prog_name);
-    exit();
+    exit(0);
 }
\ No newline at end of file
diff --git a/Ubiquitous/XiZi_AIoT/services/drivers/imx6q-sabrelite/clock/timer.c b/Ubiquitous/XiZi_AIoT/services/drivers/imx6q-sabrelite/clock/timer.c
index 1f77c76c5..997c6fda6 100644
--- a/Ubiquitous/XiZi_AIoT/services/drivers/imx6q-sabrelite/clock/timer.c
+++ b/Ubiquitous/XiZi_AIoT/services/drivers/imx6q-sabrelite/clock/timer.c
@@ -109,20 +109,21 @@ void system_time_init(void)
 
 int IPC_DO_SERVE_FUNC(Ipc_delay_us)(uint32_t* usecs)
 {
-    // uint32_t instance = g_system_timer_port;
-    // if (*usecs == 0) {
-    //     return 0;
-    // }
+    uint32_t instance = g_system_timer_port;
+    if (*usecs == 0) {
+        return 0;
+    }
 
-    // /* enable the counter first */
-    // epit_counter_enable(instance, *usecs, POLLING_MODE);
+    /* enable the counter first */
+    epit_counter_enable(instance, *usecs, POLLING_MODE);
 
-    // /* wait for the compare event */
-    // while (!epit_get_compare_event(instance))
-    //     ;
+    /* wait for the compare event */
+    while (!epit_get_compare_event(instance)) {
+        yield(SYS_TASK_YIELD_NO_REASON);
+    }
 
-    // /* disable the counter to save power */
-    // epit_counter_disable(instance);
+    /* disable the counter to save power */
+    epit_counter_disable(instance);
     return 0;
 }
 
@@ -177,7 +178,7 @@ int main(int argc, char** argv)
     static char server_name[] = "TimerServer";
     if (register_server(server_name) < 0) {
         printf("register server name %s failed\n", server_name);
-        exit();
+        exit(1);
     }
 
     static uint32_t epit_instance = HW_EPIT2;
@@ -187,7 +188,7 @@ int main(int argc, char** argv)
 
     ipc_server_loop(&IpcSabreliteTimer);
 
-    exit();
+    exit(0);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/Ubiquitous/XiZi_AIoT/services/drivers/imx6q-sabrelite/enet/Makefile b/Ubiquitous/XiZi_AIoT/services/drivers/imx6q-sabrelite/enet/Makefile
index 6741c8fb1..40096c142 100644
--- a/Ubiquitous/XiZi_AIoT/services/drivers/imx6q-sabrelite/enet/Makefile
+++ b/Ubiquitous/XiZi_AIoT/services/drivers/imx6q-sabrelite/enet/Makefile
@@ -18,7 +18,7 @@ cflags = -std=c11 -march=armv7-a -mcpu=cortex-a9 -mtune=cortex-a9 -g \
 # cflags = -std=c11 -march=armv7-a -mtune=cortex-a9 -nostdlib -nodefaultlibs -mfloat-abi=soft -fno-pic \
 # 	-static -fno-builtin -fno-strict-aliasing -Wall -ggdb -Wno-unused -Werror -fno-omit-frame-pointer -fno-stack-protector -fno-pie 
 
-c_useropts = -O2
+c_useropts = -O0
 
 INC_DIR = 	-I$(KERNEL_ROOT)/services/app \
 		  	-I$(KERNEL_ROOT)/services/boards/$(BOARD) \
diff --git a/Ubiquitous/XiZi_AIoT/services/drivers/imx6q-sabrelite/enet/enet_drv.c b/Ubiquitous/XiZi_AIoT/services/drivers/imx6q-sabrelite/enet/enet_drv.c
index c1f0de0d6..efb58e98f 100755
--- a/Ubiquitous/XiZi_AIoT/services/drivers/imx6q-sabrelite/enet/enet_drv.c
+++ b/Ubiquitous/XiZi_AIoT/services/drivers/imx6q-sabrelite/enet/enet_drv.c
@@ -555,8 +555,6 @@ void imx_enet_start(imx_enet_priv_t* dev, unsigned char* enaddr)
     dev->tx_busy = 0;
     dev->enet_reg->ECR.U |= ENET_ETHER_EN | ENET_ETHER_SPEED_1000M | ENET_ETHER_LITTLE_ENDIAN;
     dev->enet_reg->RDAR.U |= ENET_RX_TX_ACTIVE;
-    HW_ENET_RDAR_WR(ENET_RX_TX_ACTIVE);
-    printf("addr1: %x, addr2: %x\n", &dev->enet_reg->RDAR.U, HW_ENET_RDAR_ADDR);
     printf("EIR: %08x, ECR: %08x, TDAR.U: %08x, RDAR.U: %08x (%08x)\n", dev->enet_reg->EIR.U, dev->enet_reg->ECR.U, dev->enet_reg->TDAR.U, dev->enet_reg->RDAR.U, ENET_RX_TX_ACTIVE);
 }
 
diff --git a/Ubiquitous/XiZi_AIoT/services/drivers/imx6q-sabrelite/enet/enet_test.c b/Ubiquitous/XiZi_AIoT/services/drivers/imx6q-sabrelite/enet/enet_test.c
index c76d22ebe..52d18b2fd 100755
--- a/Ubiquitous/XiZi_AIoT/services/drivers/imx6q-sabrelite/enet/enet_test.c
+++ b/Ubiquitous/XiZi_AIoT/services/drivers/imx6q-sabrelite/enet/enet_test.c
@@ -145,7 +145,6 @@ void print_hw_enet(const hw_enet_t* enet)
  */
 int enet_test()
 {
-
     imx_enet_priv_t* dev0 = &enet0;
     int pkt_len_send = 0, pkt_len_recv = 0, ret = 0, i;
     unsigned int enet_events = 0;
@@ -251,23 +250,23 @@ int main(int argc, char** argv)
 {
     if (connect_session(&timer_session, timer_server_name, 4096) < 0) {
         printf("%s connect server: %s failed\n", enet_server_name, timer_server_name);
-        exit();
+        exit(1);
     }
 
     printf("%s: Mapping %08x(size: %x) to %08x\n", enet_server_name, AIPS1_ARB_PHY_BASE_ADDR, AIPS1_ARB_END_ADDR - AIPS1_ARB_BASE_ADDR, AIPS1_ARB_BASE_ADDR);
     if (!mmap(AIPS1_ARB_BASE_ADDR, AIPS1_ARB_PHY_BASE_ADDR, AIPS1_ARB_END_ADDR - AIPS1_ARB_BASE_ADDR, true)) {
         printf("%s: mmap AIPS1 ARB(%8x) failed\n", enet_server_name, AIPS1_ARB_PHY_BASE_ADDR);
-        exit();
+        exit(1);
     }
 
     printf("%s: Mapping %08x(size: %x) to %8x\n", enet_server_name, AIPS2_ARB_PHY_BASE_ADDR, AIPS2_ARB_END_ADDR - AIPS2_ARB_BASE_ADDR, AIPS2_ARB_BASE_ADDR);
     if (!mmap(AIPS2_ARB_BASE_ADDR, AIPS2_ARB_PHY_BASE_ADDR, AIPS2_ARB_END_ADDR - AIPS2_ARB_BASE_ADDR, true)) {
         printf("%s: mmap AIPS1 ARB(%08x) failed\n", enet_server_name, AIPS2_ARB_PHY_BASE_ADDR);
-        exit();
+        exit(1);
     }
 
     enet_test();
 
-    exit();
+    exit(0);
     return 0;
 }
\ No newline at end of file
diff --git a/Ubiquitous/XiZi_AIoT/services/fs/fs_server/fs_server.c b/Ubiquitous/XiZi_AIoT/services/fs/fs_server/fs_server.c
index 8d0246f7e..5f13e6737 100644
--- a/Ubiquitous/XiZi_AIoT/services/fs/fs_server/fs_server.c
+++ b/Ubiquitous/XiZi_AIoT/services/fs/fs_server/fs_server.c
@@ -358,10 +358,10 @@ int main(int argc, char* argv[])
 
     if (register_server("MemFS") < 0) {
         printf("register server name: %s failed.\n", "MemFs");
-        exit();
+        exit(1);
     }
     ipc_server_loop(&IpcFsServer);
 
     // never reached
-    exit();
+    exit(0);
 }
diff --git a/Ubiquitous/XiZi_AIoT/services/fs/fs_server/include/block_io.h b/Ubiquitous/XiZi_AIoT/services/fs/fs_server/include/block_io.h
index cf6867c94..8fd07762b 100644
--- a/Ubiquitous/XiZi_AIoT/services/fs/fs_server/include/block_io.h
+++ b/Ubiquitous/XiZi_AIoT/services/fs/fs_server/include/block_io.h
@@ -18,12 +18,13 @@
 
 // Block size
 #define BLOCK_SIZE 512
+#define NR_BIT_BLOCKS 2
 
 // bits size
 #define BITS 8
 
 // Bitmap size of one block
-#define BITMAP_SIZE (BLOCK_SIZE * BITS)
+#define BITMAP_SIZE (BLOCK_SIZE * BITS * NR_BIT_BLOCKS)
 
 // Inode size of one block
 #define INODE_SIZE (BLOCK_SIZE / sizeof(struct Inode))
diff --git a/Ubiquitous/XiZi_AIoT/services/fs/fs_server/include/fs.h b/Ubiquitous/XiZi_AIoT/services/fs/fs_server/include/fs.h
index 776cfbbea..17a536ece 100644
--- a/Ubiquitous/XiZi_AIoT/services/fs/fs_server/include/fs.h
+++ b/Ubiquitous/XiZi_AIoT/services/fs/fs_server/include/fs.h
@@ -77,6 +77,7 @@ struct SuperBlock {
     uint32_t size; // Number of total blocks of file system image
     uint32_t nblocks; // Number of data blocks
     uint32_t ninodes; // Number of inodes.
+    uint32_t nbitblocks;
 };
 
 // Inode structure
diff --git a/Ubiquitous/XiZi_AIoT/services/lib/ipc/libipc.c b/Ubiquitous/XiZi_AIoT/services/lib/ipc/libipc.c
index 7c3e22302..1f6680a0c 100644
--- a/Ubiquitous/XiZi_AIoT/services/lib/ipc/libipc.c
+++ b/Ubiquitous/XiZi_AIoT/services/lib/ipc/libipc.c
@@ -145,6 +145,7 @@ int ipc_session_wait(struct Session* session)
 }
 
 static int cur_sess_id = -1;
+static struct IpcMsg* ipc_server_loop_cur_msg = NULL;
 int cur_session_id(void)
 {
     return cur_sess_id;
@@ -161,6 +162,20 @@ bool is_cur_session_delayed(void)
     return session_delayed;
 }
 
+bool is_cur_handler_been_delayed()
+{
+    if (ipc_server_loop_cur_msg == NULL) {
+        return false;
+    }
+    return ipc_server_loop_cur_msg->header.delayed == 1;
+}
+
+bool server_set_cycle_handler(struct IpcNode* ipc_node, void (*handler)())
+{
+    ipc_node->cycle_handler = handler;
+    return true;
+}
+
 void ipc_server_loop(struct IpcNode* ipc_node)
 {
     struct Session session_list[NR_MAX_SESSION];
@@ -183,39 +198,43 @@ void ipc_server_loop(struct IpcNode* ipc_node)
                     break;
                 }
                 cur_sess_id = session_list[i].id;
-                struct IpcMsg* msg = IPCSESSION_MSG(&session_list[i]);
+                ipc_server_loop_cur_msg = IPCSESSION_MSG(&session_list[i]);
                 /* handle every message in current session
                     a session could be delay in case one of its message(current message) needs to wait for an interrupt message's arrival
                     interfaces[opcode] should explicitly call delay_session() and return to delay this session
                 */
-                while (msg->header.magic == IPC_MSG_MAGIC && msg->header.valid == 1 && msg->header.done == 0) {
+                while (ipc_server_loop_cur_msg->header.magic == IPC_MSG_MAGIC && ipc_server_loop_cur_msg->header.valid == 1 && ipc_server_loop_cur_msg->header.done == 0) {
                     // printf("session %d [%d, %d]\n", session_list[i].id, session_list[i].head, session_list[i].tail);
-                    if (session_used_size(&session_list[i]) == 0 && session_forward_tail(&session_list[i], msg->header.len) < 0) {
+                    if (session_used_size(&session_list[i]) == 0 && session_forward_tail(&session_list[i], ipc_server_loop_cur_msg->header.len) < 0) {
                         break;
                     }
 
                     // this is a message needs to handle
-                    if (ipc_node->interfaces[msg->header.opcode]) {
-                        ipc_node->interfaces[msg->header.opcode](msg);
+                    if (ipc_node->interfaces[ipc_server_loop_cur_msg->header.opcode]) {
+                        ipc_node->interfaces[ipc_server_loop_cur_msg->header.opcode](ipc_server_loop_cur_msg);
                         // check if this session is delayed by op handler, all messages after the delayed message in current session is blocked.
                         if (is_cur_session_delayed()) {
-                            msg->header.delayed = 1;
+                            ipc_server_loop_cur_msg->header.delayed = 1;
                             has_delayed = true;
                             break;
                         }
                     } else {
-                        printf("Unsupport opcode(%d) for server: %s\n", msg->header.opcode, ipc_node->name);
+                        printf("Unsupport opcode(%d) for server: %s\n", ipc_server_loop_cur_msg->header.opcode, ipc_node->name);
                     }
                     // current msg is a message that needs to ignore
                     // finish this message in server's perspective
-                    if (session_forward_head(&session_list[i], msg->header.len) < 0) {
+                    if (session_forward_head(&session_list[i], ipc_server_loop_cur_msg->header.len) < 0) {
                         break;
                     }
-                    msg = IPCSESSION_MSG(&session_list[i]);
+                    ipc_server_loop_cur_msg = IPCSESSION_MSG(&session_list[i]);
                 }
                 // stop handle this session
                 cur_sess_id = -1;
+                ipc_server_loop_cur_msg = NULL;
             }
         }
+        if (ipc_node->cycle_handler) {
+            ipc_node->cycle_handler();
+        }
     }
 }
\ No newline at end of file
diff --git a/Ubiquitous/XiZi_AIoT/services/lib/ipc/libipc.h b/Ubiquitous/XiZi_AIoT/services/lib/ipc/libipc.h
index 480a5d2cd..6a8f83e0e 100644
--- a/Ubiquitous/XiZi_AIoT/services/lib/ipc/libipc.h
+++ b/Ubiquitous/XiZi_AIoT/services/lib/ipc/libipc.h
@@ -76,6 +76,7 @@ typedef int (*IpcInterface)(struct IpcMsg* msg);
 struct IpcNode {
     char* name;
     IpcInterface interfaces[UINT8_MAX];
+    void (*cycle_handler)();
 } __attribute__((packed));
 
 #define IPC_SERVER_LOOP(ipc_node_name) rpc_server_loop_##rpc_node_name
@@ -242,4 +243,6 @@ bool is_cur_session_delayed(void);
     }
 
 int cur_session_id(void);
-void delay_session(void);
\ No newline at end of file
+bool server_set_cycle_handler(struct IpcNode* ipc_node, void (*handler)());
+void delay_session(void);
+bool is_cur_handler_been_delayed();
\ No newline at end of file
diff --git a/Ubiquitous/XiZi_AIoT/services/lib/usyscall/usyscall.c b/Ubiquitous/XiZi_AIoT/services/lib/usyscall/usyscall.c
index 8570c0f98..77d96be01 100644
--- a/Ubiquitous/XiZi_AIoT/services/lib/usyscall/usyscall.c
+++ b/Ubiquitous/XiZi_AIoT/services/lib/usyscall/usyscall.c
@@ -26,9 +26,9 @@ int spawn(struct Session* session, int fd, ipc_read_fn ipc_read, ipc_fsize_fn ip
     return ret;
 }
 
-int exit()
+void exit(int status)
 {
-    return syscall(SYSCALL_EXIT, 0, 0, 0, 0);
+    syscall(SYSCALL_EXIT, (uintptr_t)status, 0, 0, 0);
 }
 
 int yield(task_yield_reason reason)
diff --git a/Ubiquitous/XiZi_AIoT/services/lib/usyscall/usyscall.h b/Ubiquitous/XiZi_AIoT/services/lib/usyscall/usyscall.h
index 822831942..68b488da7 100644
--- a/Ubiquitous/XiZi_AIoT/services/lib/usyscall/usyscall.h
+++ b/Ubiquitous/XiZi_AIoT/services/lib/usyscall/usyscall.h
@@ -65,7 +65,7 @@ typedef int (*ipc_write_fn)(struct Session* session, int fd, char* src, int offs
 int syscall(int sys_num, intptr_t a1, intptr_t a2, intptr_t a3, intptr_t a4);
 
 int spawn(struct Session* session, int fd, ipc_read_fn ipc_read, ipc_fsize_fn ipc_fsize, char* name, char** argv);
-int exit();
+void exit(int status);
 int yield(task_yield_reason reason);
 int kill(int pid);
 int register_server(char* name);
diff --git a/Ubiquitous/XiZi_AIoT/services/tools/mkfs/mkfs.c b/Ubiquitous/XiZi_AIoT/services/tools/mkfs/mkfs.c
index f7ee5203e..027d9dd5c 100755
--- a/Ubiquitous/XiZi_AIoT/services/tools/mkfs/mkfs.c
+++ b/Ubiquitous/XiZi_AIoT/services/tools/mkfs/mkfs.c
@@ -52,7 +52,7 @@ Modification:
 
 int fsfd;
 struct SuperBlock sb;
-char zeroes[512];
+char zeroes[BLOCK_SIZE];
 uint freeblock;
 uint usedblocks;
 uint bitblocks;
@@ -93,7 +93,7 @@ int main(int argc, char* argv[])
     int i, cc, fd;
     uint rootino, inum, off;
     struct DirEntry de;
-    char buf[512];
+    char buf[BLOCK_SIZE];
     struct Inode din;
     int size, nblocks;
 
@@ -104,8 +104,8 @@ int main(int argc, char* argv[])
         exit(1);
     }
 
-    assert((512 % sizeof(struct Inode)) == 0);
-    assert((512 % sizeof(struct DirEntry)) == 0);
+    assert((BLOCK_SIZE % sizeof(struct Inode)) == 0);
+    assert((BLOCK_SIZE % sizeof(struct DirEntry)) == 0);
 
     fsfd = open(argv[1], O_RDWR | O_CREAT | O_TRUNC, 0666);
     if (fsfd < 0) {
@@ -114,7 +114,7 @@ int main(int argc, char* argv[])
     }
 
     size = nr_blocks_total;
-    bitblocks = size / (512 * 8) + 1;
+    bitblocks = NR_BIT_BLOCKS;
     usedblocks = 2 + (nr_inodes / INODE_SIZE + 1) + bitblocks;
     nblocks = nr_blocks_total - usedblocks;
     freeblock = usedblocks;
@@ -122,6 +122,7 @@ int main(int argc, char* argv[])
     sb.size = xint(size);
     sb.nblocks = xint(nblocks);
     sb.ninodes = xint(nr_inodes);
+    sb.nbitblocks = xint(NR_BIT_BLOCKS);
 
     printf("block 0 is unused, block 1 is for super block, used %d (bit %d ninode %zu) free %u total %d\n", usedblocks,
         bitblocks, nr_inodes / INODE_SIZE + 1, size - usedblocks, nblocks + usedblocks);
@@ -192,11 +193,11 @@ int main(int argc, char* argv[])
 
 void wsect(uint sec, void* buf)
 {
-    if (lseek(fsfd, sec * 512L, 0) != sec * 512L) {
+    if (lseek(fsfd, sec * BLOCK_SIZE, 0) != sec * BLOCK_SIZE) {
         perror("lseek");
         exit(1);
     }
-    if (write(fsfd, buf, 512) != 512) {
+    if (write(fsfd, buf, BLOCK_SIZE) != BLOCK_SIZE) {
         perror("write");
         exit(1);
     }
@@ -209,7 +210,7 @@ uint i2b(uint inum)
 
 void winode(uint inum, struct Inode* ip)
 {
-    char buf[512];
+    char buf[BLOCK_SIZE];
     uint bn;
     struct Inode* dip;
 
@@ -222,7 +223,7 @@ void winode(uint inum, struct Inode* ip)
 
 void rinode(uint inum, struct Inode* ip)
 {
-    char buf[512];
+    char buf[BLOCK_SIZE];
     uint bn;
     struct Inode* dip;
 
@@ -234,11 +235,11 @@ void rinode(uint inum, struct Inode* ip)
 
 void rsect(uint sec, void* buf)
 {
-    if (lseek(fsfd, sec * 512L, 0) != sec * 512L) {
+    if (lseek(fsfd, sec * BLOCK_SIZE, 0) != sec * BLOCK_SIZE) {
         perror("lseek");
         exit(1);
     }
-    if (read(fsfd, buf, 512) != 512) {
+    if (read(fsfd, buf, BLOCK_SIZE) != BLOCK_SIZE) {
         perror("read");
         exit(1);
     }
@@ -259,17 +260,18 @@ uint ialloc(ushort type)
 
 void balloc(int used)
 {
-    uchar buf[512];
+    uchar buf[BLOCK_SIZE];
     int i;
-
     printf("balloc: first %d blocks have been allocated\n", used);
-    assert(used < 512 * 8);
-    bzero(buf, 512);
-    for (i = 0; i < used; i++) {
-        buf[i / 8] = buf[i / 8] | (0x1 << (i % 8));
+    bzero(buf, BLOCK_SIZE);
+    for (int bmsec = 0; bmsec < bitblocks; bmsec++) {
+        for (i = 0; i < ((used > NR_BIT_PER_BYTE * BLOCK_SIZE) ? NR_BIT_PER_BYTE * BLOCK_SIZE : used); i++) {
+            buf[i / NR_BIT_PER_BYTE] = buf[i / NR_BIT_PER_BYTE] | (0x1 << (i % NR_BIT_PER_BYTE));
+        }
+        printf("balloc: write bitmap block at sector %zu\n", nr_inodes / INODE_SIZE + 3 + bmsec);
+        wsect(nr_inodes / INODE_SIZE + 3 + bmsec, buf);
+        used -= NR_BIT_PER_BYTE * BLOCK_SIZE;
     }
-    printf("balloc: write bitmap block at sector %zu\n", nr_inodes / INODE_SIZE + 3);
-    wsect(nr_inodes / INODE_SIZE + 3, buf);
 }
 
 #define min(a, b) ((a) < (b) ? (a) : (b))
@@ -279,7 +281,7 @@ void iappend(uint inum, void* xp, int n)
     char* p = (char*)xp;
     uint fbn, off, n1;
     struct Inode din;
-    char buf[512];
+    char buf[BLOCK_SIZE];
     uint indirect[NR_INDIRECT_BLOCKS * MAX_INDIRECT_BLOCKS];
     uint x;
 
@@ -287,7 +289,7 @@ void iappend(uint inum, void* xp, int n)
 
     off = xint(din.size);
     while (n > 0) {
-        fbn = off / 512;
+        fbn = off / BLOCK_SIZE;
         assert(fbn < MAX_FILE_SIZE);
         assert(usedblocks < nr_blocks_total);
         if (fbn < NR_DIRECT_BLOCKS) {
@@ -315,9 +317,9 @@ void iappend(uint inum, void* xp, int n)
                 x = xint(indirect[idx]);
             }
         }
-        n1 = min(n, (fbn + 1) * 512 - off);
+        n1 = min(n, (fbn + 1) * BLOCK_SIZE - off);
         rsect(x, buf);
-        bcopy(p, buf + off - (fbn * 512), n1);
+        bcopy(p, buf + off - (fbn * BLOCK_SIZE), n1);
         wsect(x, buf);
         n -= n1;
         off += n1;
diff --git a/Ubiquitous/XiZi_AIoT/services/tools/mkfs/mkfs.h b/Ubiquitous/XiZi_AIoT/services/tools/mkfs/mkfs.h
index 3590334ab..b7d299bb9 100755
--- a/Ubiquitous/XiZi_AIoT/services/tools/mkfs/mkfs.h
+++ b/Ubiquitous/XiZi_AIoT/services/tools/mkfs/mkfs.h
@@ -48,8 +48,9 @@ Modification:
 
 #define ROOT_INUM 1 // root inode number
 #define BLOCK_SIZE 512 // block size
-#define BITMAP_SIZE 1024
-#define nr_blocks_total 8192 // total number of blocks (including used blocks and free blocks)
+#define NR_BIT_PER_BYTE 8
+#define NR_BIT_BLOCKS 2
+#define nr_blocks_total (BLOCK_SIZE * NR_BIT_PER_BYTE * NR_BIT_BLOCKS) // total number of blocks (including used blocks and free blocks)
 #define nr_inodes 200 // total number of inodes
 
 #define NR_DIRECT_BLOCKS 4
@@ -70,6 +71,7 @@ struct SuperBlock {
     uint size; // Size of file system image (blocks)
     uint nblocks; // Number of data blocks
     uint ninodes; // Number of inodes.
+    uint nbitblocks;
 };
 
 // Inode structure