diff --git a/Ubiquitous/XiZi_AIoT/services/app/Makefile b/Ubiquitous/XiZi_AIoT/services/app/Makefile
index 1cab0da46..a7d4c0684 100644
--- a/Ubiquitous/XiZi_AIoT/services/app/Makefile
+++ b/Ubiquitous/XiZi_AIoT/services/app/Makefile
@@ -33,9 +33,9 @@ INC_DIR = 	-I$(KERNEL_ROOT)/services/shell/letter-shell \
 			-I$(KERNEL_ROOT)/services/app 
 
 ifeq ($(BOARD), imx6q-sabrelite)
-all: init test_fault simple_client simple_server shell fs_server semaphore_server test_ipc_null test_thread test_irq_hdlr test_irq_block test_irq_send eth_driver epit_server readme.txt | bin
+all: init test_fault simple_client simple_server shell fs_server semaphore_server test_semaphore test_ipc_null test_thread test_irq_hdlr test_irq_block test_irq_send eth_driver epit_server readme.txt | bin
 else 
-all: init test_fault simple_client simple_server shell fs_server readme.txt | bin
+all: init test_fault simple_client simple_server shell fs_server test_ipc_null test_thread test_semaphore readme.txt | bin
 endif
 	../tools/mkfs/mkfs ./fs.img $^
 	@mv $(filter-out readme.txt, $^) bin
@@ -59,6 +59,10 @@ epit_server: timer.o epit.o ccm_pll.o usyscall.o arch_usyscall.o libserial.o pri
 	@${objdump} -S $@ > $@.asm
 endif
 
+test_semaphore: test_semaphore.o libserial.o printf.o usyscall.o arch_usyscall.o
+	@${ld} ${user_ldflags} -e main -o $@ $^ ${board_specs}
+	@${objdump} -S $@ > $@.asm
+
 test_ipc_null: test_ipc_null.o libserial.o printf.o usyscall.o arch_usyscall.o libipc.o session.o
 	@${ld} ${user_ldflags} -e main -o $@ $^ ${board_specs}
 	@${objdump} -S $@ > $@.asm
diff --git a/Ubiquitous/XiZi_AIoT/services/app/test_fault.c b/Ubiquitous/XiZi_AIoT/services/app/test_fault.c
index 03d8e4b32..a38563c57 100644
--- a/Ubiquitous/XiZi_AIoT/services/app/test_fault.c
+++ b/Ubiquitous/XiZi_AIoT/services/app/test_fault.c
@@ -18,7 +18,6 @@
 #include "libserial.h"
 #include "usyscall.h"
 
-#define BLOCK_SIZE 256
 int main(int argc, char* argv[])
 {
     printf("Test memry error %s.\n", 0x50000000);
diff --git a/Ubiquitous/XiZi_AIoT/services/app/test_semaphore.c b/Ubiquitous/XiZi_AIoT/services/app/test_semaphore.c
new file mode 100644
index 000000000..a682ec11b
--- /dev/null
+++ b/Ubiquitous/XiZi_AIoT/services/app/test_semaphore.c
@@ -0,0 +1,71 @@
+/*
+ * Copyright (c) 2020 AIIT XUOS Lab
+ * XiUOS is licensed under Mulan PSL v2.
+ * You can use this software according to the terms and conditions of the Mulan PSL v2.
+ * You may obtain a copy of Mulan PSL v2 at:
+ *        http://license.coscl.org.cn/MulanPSL2
+ * THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
+ * EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
+ * MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
+ * See the Mulan PSL v2 for more details.
+ */
+#include <stdint.h>
+
+#include "libserial.h"
+#include "usyscall.h"
+
+enum {
+    NR_THREADS = 16,
+    LOOP_TIMES = 0x1000000,
+};
+
+static int sem_id = -1;
+static uint32_t sum = 0;
+static int nr_thds = NR_THREADS;
+
+int do_calculation(int argc, char** argv)
+{
+    for (uint32_t i = 0; i < LOOP_TIMES; i++) {
+        sum++;
+    }
+
+    printf("test semaphore thd signal.\n");
+    semaphore_signal(sem_id);
+
+    char* params[] = { "do_cal", NULL };
+    if (nr_thds != 0) {
+        int tid = thread(do_calculation, "test_sem_thd", params);
+        nr_thds--;
+    }
+
+    exit(0);
+    return 0;
+}
+
+int main(int argc, char** argv)
+{
+    printf("Test Semaphore.\n");
+    sem_id = semaphore_new(0);
+    if (sem_id < 0) {
+        printf("new a kernel sem failed.\n");
+        exit(1);
+    }
+
+    sum = 0;
+
+    nr_thds = NR_THREADS;
+    char* params[] = { "do_cal", NULL };
+    if (nr_thds != 0) {
+        int tid = thread(do_calculation, "test_sem_thd", params);
+        nr_thds--;
+    }
+
+    for (int i = 0; i < NR_THREADS; i++) {
+        semaphore_wait(sem_id);
+    }
+
+    printf("test thread sum after %d signal: 0x%x\n", NR_THREADS, sum);
+
+    exit(0);
+    return 0;
+}
diff --git a/Ubiquitous/XiZi_AIoT/services/lib/usyscall/usyscall.c b/Ubiquitous/XiZi_AIoT/services/lib/usyscall/usyscall.c
index 1e3d2da9b..9331c8546 100644
--- a/Ubiquitous/XiZi_AIoT/services/lib/usyscall/usyscall.c
+++ b/Ubiquitous/XiZi_AIoT/services/lib/usyscall/usyscall.c
@@ -109,4 +109,24 @@ int mmap(uintptr_t vaddr, uintptr_t paddr, int len, bool is_dev)
 int register_irq(int irq, int opcode)
 {
     return syscall(SYSCALL_REGISTER_IRQ, (intptr_t)irq, (intptr_t)opcode, 0, 0);
+}
+
+int semaphore_new(int val)
+{
+    return syscall(SYSCALL_SEMAPHORE, (intptr_t)SYS_SEM_NEW, (intptr_t)val, 0, 0);
+}
+
+bool semaphore_free(int sem_id)
+{
+    return syscall(SYSCALL_SEMAPHORE, (intptr_t)SYS_SEM_FREE, (intptr_t)sem_id, 0, 0);
+}
+
+bool semaphore_wait(int sem_id)
+{
+    return syscall(SYSCALL_SEMAPHORE, (intptr_t)SYS_SEM_WAIT, (intptr_t)sem_id, 0, 0);
+}
+
+bool semaphore_signal(int sem_id)
+{
+    return syscall(SYSCALL_SEMAPHORE, (intptr_t)SYS_SEM_SIGNAL, (intptr_t)sem_id, 0, 0);
 }
\ No newline at end of file
diff --git a/Ubiquitous/XiZi_AIoT/services/lib/usyscall/usyscall.h b/Ubiquitous/XiZi_AIoT/services/lib/usyscall/usyscall.h
index eda606788..8c6822ede 100644
--- a/Ubiquitous/XiZi_AIoT/services/lib/usyscall/usyscall.h
+++ b/Ubiquitous/XiZi_AIoT/services/lib/usyscall/usyscall.h
@@ -32,6 +32,8 @@
 #define SYSCALL_REGISTER_IRQ    11  //
 
 #define SYSCALL_KILL            12  // kill the task by id
+
+#define SYSCALL_SEMAPHORE       13  // semaphore related operations
 // clang-format on
 
 typedef enum {
@@ -58,6 +60,13 @@ typedef union {
     int priority;
 } sys_state_info;
 
+typedef enum {
+    SYS_SEM_NEW = 0,
+    SYS_SEM_FREE,
+    SYS_SEM_SIGNAL,
+    SYS_SEM_WAIT,
+} sys_sem_option;
+
 typedef int (*ipc_read_fn)(struct Session* session, int fd, char* dst, int offset, int len);
 typedef int (*ipc_fsize_fn)(struct Session* session, int fd);
 typedef int (*ipc_write_fn)(struct Session* session, int fd, char* src, int offset, int len);
@@ -69,15 +78,23 @@ int thread(void* entry, char* name, char** argv);
 void exit(int status);
 int yield(task_yield_reason reason);
 int kill(int pid);
+
 int register_server(char* name);
 int session(char* path, int capacity, struct Session* user_session);
 int poll_session(struct Session* userland_session_arr, int arr_capacity);
 int close_session(struct Session* session);
+int register_irq(int irq, int opcode);
+
+int mmap(uintptr_t vaddr, uintptr_t paddr, int len, bool is_dev);
+
 int task_heap_base();
 int get_memblock_info(sys_state_info* info);
 int set_priority(sys_state_info* info);
 int show_task();
 int show_mem();
 int show_cpu();
-int mmap(uintptr_t vaddr, uintptr_t paddr, int len, bool is_dev);
-int register_irq(int irq, int opcode);
\ No newline at end of file
+
+int semaphore_new(int val);
+bool semaphore_free(int sem_id);
+bool semaphore_wait(int sem_id);
+bool semaphore_signal(int sem_id);
\ No newline at end of file
diff --git a/Ubiquitous/XiZi_AIoT/softkernel/include/ksemaphore.h b/Ubiquitous/XiZi_AIoT/softkernel/include/ksemaphore.h
new file mode 100644
index 000000000..99efd6523
--- /dev/null
+++ b/Ubiquitous/XiZi_AIoT/softkernel/include/ksemaphore.h
@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2020 AIIT XUOS Lab
+ * XiUOS is licensed under Mulan PSL v2.
+ * You can use this software according to the terms and conditions of the Mulan PSL v2.
+ * You may obtain a copy of Mulan PSL v2 at:
+ *        http://license.coscl.org.cn/MulanPSL2
+ * THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
+ * EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
+ * MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
+ * See the Mulan PSL v2 for more details.
+ */
+/**
+ * @file semaphore.h
+ * @brief semaphore implementation
+ * @version 3.0
+ * @author AIIT XUOS Lab
+ * @date 2024.05.28
+ */
+#pragma once
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#include "list.h"
+#include "object_allocator.h"
+
+/// @warning this is no in use
+enum {
+    KSEM_NOWAIT = -1,
+};
+
+struct ksemaphore {
+    uint32_t id;
+    int val;
+    /* list of waiting threads */
+    struct double_list_node wait_list_guard;
+    /* list to manage semaphores */
+    /// @todo Use RB-Tree to manage all semaphores
+    struct double_list_node sem_list_node;
+};
+
+struct XiziSemaphorePool {
+    uint32_t next_sem_id;
+    struct slab_allocator allocator;
+    struct double_list_node sem_list_guard;
+};
+
+void semaphore_pool_init(struct XiziSemaphorePool* sem_pool);
+int ksemaphore_alloc(struct XiziSemaphorePool* sem_pool, int val);
+bool ksemaphore_free(struct XiziSemaphorePool* sem_pool, uint32_t sem_id);
+bool ksemaphore_signal(struct XiziSemaphorePool* sem_pool, uint32_t sem_id);
diff --git a/Ubiquitous/XiZi_AIoT/softkernel/include/syscall.h b/Ubiquitous/XiZi_AIoT/softkernel/include/syscall.h
index 96dac0b89..4e1ba2a7a 100644
--- a/Ubiquitous/XiZi_AIoT/softkernel/include/syscall.h
+++ b/Ubiquitous/XiZi_AIoT/softkernel/include/syscall.h
@@ -46,6 +46,8 @@ Modification:
 #define SYSCALL_REGISTER_IRQ    11  //
 
 #define SYSCALL_KILL            12  // kill the task by id
+
+#define SYSCALL_SEMAPHORE       13  // semaphore related operations
 // clang-format on
 
 #ifndef __ASSEMBLER__
@@ -78,9 +80,12 @@ typedef union {
     int priority;
 } sys_state_info;
 
-/* fn pointer to access user server */
-typedef int (*ipc_read_fn)(struct Session* session, int fd, char* dst, int offset, int len);
-typedef int (*ipc_write_fn)(struct Session* session, int fd, char* src, int offset, int len);
+typedef enum {
+    SYS_SEM_NEW = 0,
+    SYS_SEM_FREE,
+    SYS_SEM_SIGNAL,
+    SYS_SEM_WAIT,
+} sys_sem_option;
 
 int syscall(int sys_num, uintptr_t param1, uintptr_t param2, uintptr_t param3, uintptr_t param4);
 
@@ -102,4 +107,6 @@ int sys_mmap(uintptr_t vaddr, uintptr_t paddr, int len, int is_dev);
 int sys_register_irq(int irq_num, int irq_opcode);
 int sys_unbind_irq_all(struct Thread* task);
 int sys_unbind_irq(struct Thread* task, int irq_num);
+
+int sys_semaphore(sys_sem_option op, int sem_id);
 #endif
diff --git a/Ubiquitous/XiZi_AIoT/softkernel/include/task.h b/Ubiquitous/XiZi_AIoT/softkernel/include/task.h
index b7cf198b4..56320be0f 100644
--- a/Ubiquitous/XiZi_AIoT/softkernel/include/task.h
+++ b/Ubiquitous/XiZi_AIoT/softkernel/include/task.h
@@ -33,6 +33,7 @@ Modification:
 
 #include "bitmap64.h"
 #include "buddy.h"
+#include "ksemaphore.h"
 #include "list.h"
 #include "object_allocator.h"
 #include "pagetable.h"
@@ -121,9 +122,11 @@ struct SchedulerRightGroup {
 };
 
 struct XiziTaskManager {
+    /* thead schedule lists */
     struct double_list_node task_list_head[TASK_MAX_PRIORITY]; /* list of task control blocks that are allocated */
     struct double_list_node task_running_list_head;
     struct double_list_node task_blocked_list_head;
+    struct XiziSemaphorePool semaphore_pool;
 
     /* mem allocator */
     struct slab_allocator memspace_allocator;
@@ -149,7 +152,7 @@ struct XiziTaskManager {
     /* call to yield current use task */
     void (*task_yield_noschedule)(struct Thread* task, bool is_blocking);
     /* block and unblock task */
-    void (*task_block)(struct Thread* task);
+    void (*task_block)(struct double_list_node* head, struct Thread* task);
     void (*task_unblock)(struct Thread* task);
     /* set task priority */
     void (*set_cur_task_priority)(int priority);
diff --git a/Ubiquitous/XiZi_AIoT/softkernel/syscall/Makefile b/Ubiquitous/XiZi_AIoT/softkernel/syscall/Makefile
index 8fac5ddff..4adbb947d 100644
--- a/Ubiquitous/XiZi_AIoT/softkernel/syscall/Makefile
+++ b/Ubiquitous/XiZi_AIoT/softkernel/syscall/Makefile
@@ -10,6 +10,7 @@ SRC_FILES := syscall.c \
 	sys_exit.c \
 	sys_state.c \
 	sys_mmap.c \
-	sys_kill.c
+	sys_kill.c \
+	sys_semaphore.c
 
 include $(KERNEL_ROOT)/compiler.mk
diff --git a/Ubiquitous/XiZi_AIoT/softkernel/syscall/sys_poll_session.c b/Ubiquitous/XiZi_AIoT/softkernel/syscall/sys_poll_session.c
index 2d893be8a..35cde916d 100644
--- a/Ubiquitous/XiZi_AIoT/softkernel/syscall/sys_poll_session.c
+++ b/Ubiquitous/XiZi_AIoT/softkernel/syscall/sys_poll_session.c
@@ -121,7 +121,7 @@ int sys_poll_session(struct Session* userland_session_arr, int arr_capacity)
         userland_session_arr[session_idx].buf = NULL;
         if (!has_middle_delete && nr_sessions_need_to_handle == 0) {
             xizi_task_manager.task_yield_noschedule(cur_task, false);
-            xizi_task_manager.task_block(cur_task);
+            xizi_task_manager.task_block(&xizi_task_manager.task_blocked_list_head, cur_task);
         }
     }
 
diff --git a/Ubiquitous/XiZi_AIoT/softkernel/syscall/sys_semaphore.c b/Ubiquitous/XiZi_AIoT/softkernel/syscall/sys_semaphore.c
new file mode 100644
index 000000000..18c0fd7e7
--- /dev/null
+++ b/Ubiquitous/XiZi_AIoT/softkernel/syscall/sys_semaphore.c
@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2020 AIIT XUOS Lab
+ * XiUOS is licensed under Mulan PSL v2.
+ * You can use this software according to the terms and conditions of the Mulan PSL v2.
+ * You may obtain a copy of Mulan PSL v2 at:
+ *        http://license.coscl.org.cn/MulanPSL2
+ * THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
+ * EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
+ * MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
+ * See the Mulan PSL v2 for more details.
+ */
+/**
+ * @file sys_semaphore.c
+ * @brief support semaphore for userland
+ * @version 3.0
+ * @author AIIT XUOS Lab
+ * @date 2024.05.29
+ */
+
+#include "ksemaphore.h"
+#include "multicores.h"
+#include "syscall.h"
+#include "task.h"
+
+extern bool ksemaphore_wait(struct XiziSemaphorePool* sem_pool, struct Thread* thd, uint32_t sem_id);
+int sys_semaphore(sys_sem_option op, int param)
+{
+    bool ret = false;
+    switch (op) {
+    case SYS_SEM_NEW: {
+        // here, param is treat as val
+        return ksemaphore_alloc(&xizi_task_manager.semaphore_pool, param);
+    }
+    case SYS_SEM_FREE: {
+        // here, param is treat as sem_id
+        ret = ksemaphore_free(&xizi_task_manager.semaphore_pool, param);
+        break;
+    }
+    case SYS_SEM_SIGNAL: {
+        ret = ksemaphore_signal(&xizi_task_manager.semaphore_pool, param);
+        break;
+    }
+    case SYS_SEM_WAIT: {
+        ret = ksemaphore_wait(&xizi_task_manager.semaphore_pool, cur_cpu()->task, param);
+        break;
+    }
+    }
+
+    if (LIKELY(ret)) {
+        return 0;
+    }
+    return -1;
+}
\ No newline at end of file
diff --git a/Ubiquitous/XiZi_AIoT/softkernel/syscall/sys_state.c b/Ubiquitous/XiZi_AIoT/softkernel/syscall/sys_state.c
index 7c95474d8..ddc3f5f69 100644
--- a/Ubiquitous/XiZi_AIoT/softkernel/syscall/sys_state.c
+++ b/Ubiquitous/XiZi_AIoT/softkernel/syscall/sys_state.c
@@ -91,6 +91,17 @@ void show_tasks(void)
         SHOWTASK_TASK_BASE_INFO(task);
     }
 
+    struct ksemaphore* sem = NULL;
+    DOUBLE_LIST_FOR_EACH_ENTRY(sem, &xizi_task_manager.semaphore_pool.sem_list_guard, sem_list_node)
+    {
+        task = NULL;
+        DOUBLE_LIST_FOR_EACH_ENTRY(task, &sem->wait_list_guard, node)
+        {
+            LOG_PRINTF("%-8s", "BLOCK");
+            SHOWTASK_TASK_BASE_INFO(task);
+        }
+    }
+
     SHOWINFO_BORDER_LINE();
     return;
 }
diff --git a/Ubiquitous/XiZi_AIoT/softkernel/syscall/sys_yield.c b/Ubiquitous/XiZi_AIoT/softkernel/syscall/sys_yield.c
index 6c58e508a..0db107e04 100644
--- a/Ubiquitous/XiZi_AIoT/softkernel/syscall/sys_yield.c
+++ b/Ubiquitous/XiZi_AIoT/softkernel/syscall/sys_yield.c
@@ -43,7 +43,7 @@ int sys_yield(task_yield_reason reason)
         if (cur_task->current_ipc_handled) {
             cur_task->current_ipc_handled = false;
         } else {
-            xizi_task_manager.task_block(cur_task);
+            xizi_task_manager.task_block(&xizi_task_manager.task_blocked_list_head, cur_task);
         }
     }
 
diff --git a/Ubiquitous/XiZi_AIoT/softkernel/syscall/syscall.c b/Ubiquitous/XiZi_AIoT/softkernel/syscall/syscall.c
index 8c5891584..4a15e6389 100644
--- a/Ubiquitous/XiZi_AIoT/softkernel/syscall/syscall.c
+++ b/Ubiquitous/XiZi_AIoT/softkernel/syscall/syscall.c
@@ -77,7 +77,9 @@ int syscall(int sys_num, uintptr_t param1, uintptr_t param2, uintptr_t param3, u
     case SYSCALL_KILL:
         ret = sys_kill((int)param1);
         break;
-
+    case SYSCALL_SEMAPHORE:
+        ret = sys_semaphore((sys_sem_option)param1, (int)param2);
+        break;
     default:
         ERROR("Unsurport syscall(%d) right now\n", sys_num);
         ret = -1;
diff --git a/Ubiquitous/XiZi_AIoT/softkernel/task/Makefile b/Ubiquitous/XiZi_AIoT/softkernel/task/Makefile
index d5673c163..b2e54c9c1 100644
--- a/Ubiquitous/XiZi_AIoT/softkernel/task/Makefile
+++ b/Ubiquitous/XiZi_AIoT/softkernel/task/Makefile
@@ -1,3 +1,6 @@
-SRC_FILES := task.c schedule.c memspace.c
+SRC_FILES := task.c \
+			schedule.c \
+			memspace.c \
+			semaphore.c
 
 include $(KERNEL_ROOT)/compiler.mk
diff --git a/Ubiquitous/XiZi_AIoT/softkernel/task/semaphore.c b/Ubiquitous/XiZi_AIoT/softkernel/task/semaphore.c
new file mode 100644
index 000000000..575e1aa7d
--- /dev/null
+++ b/Ubiquitous/XiZi_AIoT/softkernel/task/semaphore.c
@@ -0,0 +1,134 @@
+/*
+ * Copyright (c) 2020 AIIT XUOS Lab
+ * XiUOS is licensed under Mulan PSL v2.
+ * You can use this software according to the terms and conditions of the Mulan PSL v2.
+ * You may obtain a copy of Mulan PSL v2 at:
+ *        http://license.coscl.org.cn/MulanPSL2
+ * THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
+ * EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
+ * MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
+ * See the Mulan PSL v2 for more details.
+ */
+/**
+ * @file semaphore.c
+ * @brief semaphore implementation
+ * @version 3.0
+ * @author AIIT XUOS Lab
+ * @date 2024.05.28
+ */
+
+#include "assert.h"
+#include "ksemaphore.h"
+#include "task.h"
+
+void semaphore_pool_init(struct XiziSemaphorePool* sem_pool)
+{
+    assert(sem_pool != NULL);
+    sem_pool->next_sem_id = 1;
+    slab_init(&sem_pool->allocator, sizeof(struct ksemaphore));
+    doubleListNodeInit(&sem_pool->sem_list_guard);
+}
+
+static inline struct ksemaphore* ksemaphore_get_by_id(struct XiziSemaphorePool* sem_pool, int sem_id)
+{
+    struct ksemaphore* sem = NULL;
+    DOUBLE_LIST_FOR_EACH_ENTRY(sem, &sem_pool->sem_list_guard, sem_list_node)
+    {
+        if (sem->id == sem_id) {
+            break;
+        }
+    }
+    return sem;
+}
+
+int ksemaphore_alloc(struct XiziSemaphorePool* sem_pool, int val)
+{
+    struct ksemaphore* sem = (struct ksemaphore*)slab_alloc(&sem_pool->allocator);
+    if (sem == NULL) {
+        ERROR("No memeory to alloc new semaphore.\n");
+        return -1;
+    }
+
+    /* No error down here */
+    /* init ksemaphore since here */
+    /// @warning sem->id could overflow
+    sem->id = sem_pool->next_sem_id++;
+    if (UNLIKELY(sem->id == 0)) {
+        slab_free(&sem_pool->allocator, sem);
+        return -1;
+    }
+    sem->val = val;
+    doubleListNodeInit(&sem->sem_list_node);
+    doubleListNodeInit(&sem->wait_list_guard);
+
+    /* list sem to sem_pool */
+    doubleListAddOnHead(&sem->sem_list_node, &sem_pool->sem_list_guard);
+
+    return sem->id;
+}
+
+bool ksemaphore_wait(struct XiziSemaphorePool* sem_pool, struct Thread* thd, uint32_t sem_id)
+{
+    assert(thd != NULL);
+    assert(thd->state == RUNNING);
+    /* find sem */
+    struct ksemaphore* sem = ksemaphore_get_by_id(sem_pool, sem_id);
+    // invalid sem id
+    if (sem == NULL) {
+        return false;
+    }
+
+    // no need to wait
+    if (sem->val > 0) {
+        sem->val--;
+        return true;
+    }
+
+    // waiting at the sem
+    sem->val--;
+    xizi_task_manager.task_yield_noschedule(thd, false);
+    xizi_task_manager.task_block(&sem->wait_list_guard, thd);
+    return true;
+}
+
+bool ksemaphore_signal(struct XiziSemaphorePool* sem_pool, uint32_t sem_id)
+{
+    /* find sem */
+    struct ksemaphore* sem = ksemaphore_get_by_id(sem_pool, sem_id);
+    // invalid sem id
+    if (sem == NULL) {
+        return false;
+    }
+
+    if (sem->val < 0) {
+        if (!IS_DOUBLE_LIST_EMPTY(&sem->wait_list_guard)) {
+            assert(sem->wait_list_guard.next != NULL);
+            xizi_task_manager.task_unblock(CONTAINER_OF(sem->wait_list_guard.next, struct Thread, node));
+        }
+    }
+
+    sem->val++;
+    return true;
+}
+
+bool ksemaphore_free(struct XiziSemaphorePool* sem_pool, uint32_t sem_id)
+{
+    /* find sem */
+    struct ksemaphore* sem = ksemaphore_get_by_id(sem_pool, sem_id);
+    // invalid sem id
+    if (sem == NULL) {
+        return false;
+    }
+
+    struct Thread* thd = NULL;
+    DOUBLE_LIST_FOR_EACH_ENTRY(thd, &sem->wait_list_guard, node)
+    {
+        assert(thd != NULL);
+        xizi_task_manager.task_unblock(thd);
+    }
+
+    doubleListDel(&sem->sem_list_node);
+    slab_free(&sem_pool->allocator, sem);
+
+    return true;
+}
diff --git a/Ubiquitous/XiZi_AIoT/softkernel/task/task.c b/Ubiquitous/XiZi_AIoT/softkernel/task/task.c
index 55cb2d2c6..4f9756e1d 100644
--- a/Ubiquitous/XiZi_AIoT/softkernel/task/task.c
+++ b/Ubiquitous/XiZi_AIoT/softkernel/task/task.c
@@ -74,6 +74,7 @@ static void _task_manager_init()
     slab_init(&xizi_task_manager.memspace_allocator, sizeof(struct MemSpace));
     slab_init(&xizi_task_manager.task_allocator, sizeof(struct Thread));
     slab_init(&xizi_task_manager.task_buddy_allocator, sizeof(struct KBuddy));
+    semaphore_pool_init(&xizi_task_manager.semaphore_pool);
 
     // tid pool
     xizi_task_manager.next_pid = 0;
@@ -321,13 +322,14 @@ static void _task_yield_noschedule(struct Thread* task, bool blocking)
     task_node_add_to_ready_list_back(task);
 }
 
-static void _task_block(struct Thread* task)
+static void _task_block(struct double_list_node* head, struct Thread* task)
 {
+    assert(head != NULL);
     assert(task != NULL);
     assert(task->state != RUNNING);
     task_node_leave_list(task);
     task->state = BLOCKED;
-    doubleListAddOnHead(&task->node, &xizi_task_manager.task_blocked_list_head);
+    doubleListAddOnHead(&task->node, head);
 }
 
 static void _task_unblock(struct Thread* task)