diff --git a/source/ucli/ucli-lib.cc b/source/ucli/ucli-lib.cc
index 3536d1e..a329744 100644
--- a/source/ucli/ucli-lib.cc
+++ b/source/ucli/ucli-lib.cc
@@ -72,7 +72,11 @@ long diag_call_ioctl(unsigned long request, unsigned long arg) {
   fd = open(DEVICE, O_RDWR, 0);
   if (fd < 0) {
     printf("open %s error!\n", DEVICE);
-    return -EEXIST;
+    fd = open(DEVICE_BAK, O_RDWR, 0);
+    if (fd < 0){
+       printf("open %s error!\n", DEVICE_BAK);
+       return EEXIST;
+    }
   }
 
   ret = ioctl(fd, request, arg);
diff --git a/source/ucli/ucli.cc b/source/ucli/ucli.cc
index cda768d..750f1d4 100644
--- a/source/ucli/ucli.cc
+++ b/source/ucli/ucli.cc
@@ -9,12 +9,76 @@
 #include <sys/ioctl.h> // for ioctl
 #include <unistd.h>
 
+// #include <fcntl.h>
+// #include <sched.h>
+// // #include <unistd.h>
+// #include <stdio.h>
+// #include <stdlib.h>
+
 // ioctl
 // !todo move to a header file
 #define IOCTL_MAGIC_NUMBER 'k'
 #define IOCTL_PID _IOWR(IOCTL_MAGIC_NUMBER, 2, int)
 #define IOCTL_TGID _IOWR(IOCTL_MAGIC_NUMBER, 3, int)
 
+// int switch_namespace(pid_t pid, const char *ns) {
+//     char ns_path[256];
+//     snprintf(ns_path, sizeof(ns_path), "/proc/%d/ns/%s", pid, ns);
+
+//     int fd = open(ns_path, O_RDONLY);
+//     if (fd == -1) {
+//         perror("open");
+//         return -1;
+//     }
+
+//     if (setns(fd, 0) == -1) {
+//         perror("setns");
+//         close(fd);
+//         return -1;
+//     }
+
+//     close(fd);
+//     return 0;
+// }
+
+// int switch_to_pid_namespace(pid_t pid) {
+//     return switch_namespace(pid, "pid");
+// }
+
+// void test(variable_monitor_task *tsk_info) {
+//   // host
+//   if (tsk_info->task.pid == tsk_info->task.container_pid){
+//     printf("host\n");
+//     diag_printf_raw_stack(tsk_info->task.tgid, tsk_info->task.container_tgid,
+//                           tsk_info->task.comm, &tsk_info->raw_stack);
+//   }
+
+//   printf("container\n");
+
+//   // Save the current namespace.
+//   int fd = open("/proc/self/ns/pid", O_RDONLY);
+//   if (fd == -1) {
+//     perror("open");
+//     return;
+//   }
+//   // Switch to the namespace of the target process.
+//   if (switch_to_pid_namespace(tsk_info->task.pid) != 0) {
+//     close(fd);
+//     return;
+//   }
+//   // Do something with tgid...
+
+//   diag_printf_raw_stack(tsk_info->task.container_tgid,
+//                         tsk_info->task.container_tgid, tsk_info->task.comm,
+//                         &tsk_info->raw_stack);
+
+//   // Switch back to the original namespace.
+//   if (!run_in_host && setns(fd, 0) == -1) {
+//     perror("setns");
+//   }
+//   close(fd);
+// }
+
 static int task_info_extract(void *buf, unsigned int len, void *) {
   int *et_type;
   variable_monitor_record *vm_record;
@@ -63,6 +127,7 @@ static int task_info_extract(void *buf, unsigned int len, void *) {
                                       : tsk_info->task.container_tgid,
                           tsk_info->task.container_tgid, tsk_info->task.comm,
                           &tsk_info->raw_stack);
+    test(tsk_info);
     diag_printf_kern_stack(&tsk_info->kern_stack);
 
     printf("#*        0xffffffffffffff %s (UNKNOWN)\n", tsk_info->task.comm);
@@ -93,7 +158,7 @@ static void do_dump(const char *arg) {
 
   struct diag_ioctl_dump_param dump_param = {
       .user_ptr_len = &len,
-      .user_buf_len = 500 * 1024 * 1024,
+      .user_buf_len = 256 * 1024 * 1024,
       .user_buf = variant_buf,
   };
 
diff --git a/source/ucli/ucli.h b/source/ucli/ucli.h
index 0aca6c1..d2d0bdb 100644
--- a/source/ucli/ucli.h
+++ b/source/ucli/ucli.h
@@ -15,6 +15,7 @@
 #define VARIABLE_MONITOR_TASK_TYPE 0x1
 
 #define DEVICE "/dev/variable_monitor"
+#define DEVICE_BAK "/host/dev/variable_monitor"
 
 #define CGROUP_NAME_LEN 32  // max length of cgroup name
 #define TASK_COMM_LEN 16    // max length of task name