diff --git a/misc/config_tools/hv_config/board_defconfig.py b/misc/config_tools/hv_config/board_defconfig.py
index 65a198486..5d47533af 100644
--- a/misc/config_tools/hv_config/board_defconfig.py
+++ b/misc/config_tools/hv_config/board_defconfig.py
@@ -13,6 +13,8 @@ import common
 DESC = """# Board defconfig generated by acrn-config tool
 """
 
+HV_RAM_SIZE_MAX = 0x40000000
+
 MEM_ALIGN = 2 * common.SIZE_M
 
 
@@ -52,14 +54,60 @@ def get_serial_type():
 
 def get_memory(hv_info, config):
 
+    # this dictonary mapped with 'address start':'mem range'
+    ram_range = {}
+
+    post_launched_vm_num = 0
+    for id in common.VM_TYPES:
+        if common.VM_TYPES[id] in scenario_cfg_lib.VM_DB and \
+                        scenario_cfg_lib.VM_DB[common.VM_TYPES[id]]["load_type"] == "POST_LAUNCHED_VM":
+            post_launched_vm_num += 1
+    hv_ram_size = common.HV_BASE_RAM_SIZE + common.POST_LAUNCHED_VM_RAM_SIZE * post_launched_vm_num
+
+    ivshmem_enabled = common.get_hv_item_tag(common.SCENARIO_INFO_FILE, "FEATURES", "IVSHMEM", "IVSHMEM_ENABLED")
+    total_shm_size = 0
+    if ivshmem_enabled == 'y':
+        raw_shmem_regions = common.get_hv_item_tag(common.SCENARIO_INFO_FILE, "FEATURES", "IVSHMEM", "IVSHMEM_REGION")
+        for raw_shm in raw_shmem_regions:
+            if raw_shm is None or raw_shm.strip() == '':
+                continue
+            raw_shm_splited = raw_shm.split(',')
+            if len(raw_shm_splited) == 3 and raw_shm_splited[0].strip() != '' \
+                    and raw_shm_splited[1].strip() != '' and len(raw_shm_splited[2].strip().split(':')) >= 1:
+                try:
+                    size = raw_shm_splited[1].strip()
+                    int_size = int(size) * 0x100000
+                    total_shm_size += int_size
+                except Exception as e:
+                    print(e)
+
+    hv_ram_size += 2 * max(total_shm_size, 0x200000)
+    if hv_ram_size > HV_RAM_SIZE_MAX:
+        common.print_red("requested RAM size should be smaller then {}".format(HV_RAM_SIZE_MAX), err=True)
+        err_dic["board config: total vm number error"] = \
+            "requested RAM size should be smaller then {}".format(HV_RAM_SIZE_MAX)
+        return err_dic
+
+    # reseve 16M memory for hv sbuf, ramoops, etc.
+    reserved_ram = 0x1000000
     # We recommend to put hv ram start address high than 0x10000000 to
     # reduce memory conflict with GRUB/Service VM Kernel.
     hv_start_offset = 0x10000000
+    total_size = reserved_ram + hv_ram_size
     for start_addr in list(board_cfg_lib.USED_RAM_RANGE):
         if hv_start_offset <= start_addr < 0x80000000:
             del board_cfg_lib.USED_RAM_RANGE[start_addr]
+    ram_range = board_cfg_lib.get_ram_range()
+    avl_start_addr = board_cfg_lib.find_avl_memory(ram_range, str(total_size), hv_start_offset)
+    hv_start_addr = int(avl_start_addr, 16) + int(hex(reserved_ram), 16)
+    hv_start_addr = common.round_up(hv_start_addr, MEM_ALIGN)
+    board_cfg_lib.USED_RAM_RANGE[hv_start_addr] = total_size
+
+    if not hv_info.mem.hv_ram_start:
+        print("CONFIG_HV_RAM_START={}".format(hex(hv_start_addr)), file=config)
+    else:
+        print("CONFIG_HV_RAM_START={}".format(hv_info.mem.hv_ram_start), file=config)
 
-    print("CONFIG_HV_RAM_START={}".format(hv_info.mem.hv_ram_start), file=config)
     print("CONFIG_STACK_SIZE={}".format(hv_info.mem.stack_size), file=config)
     print("CONFIG_IVSHMEM_ENABLED={}".format(hv_info.mem.ivshmem_enable), file=config)