diff --git a/src/dragonball/src/address_space_manager.rs b/src/dragonball/src/address_space_manager.rs
index 2e4276626b..5a54c0da01 100644
--- a/src/dragonball/src/address_space_manager.rs
+++ b/src/dragonball/src/address_space_manager.rs
@@ -642,7 +642,7 @@ impl AddressSpaceMgr {
         let node = self
             .numa_nodes
             .entry(guest_numa_node_id)
-            .or_insert(NumaNode::new());
+            .or_insert_with(NumaNode::new);
         node.add_info(&NumaNodeInfo {
             base: region.start_addr(),
             size: region.len(),
@@ -736,7 +736,7 @@ mod tests {
             .unwrap();
         val = gmem.read_obj(GuestAddress(GUEST_MEM_START + 0x1)).unwrap();
         assert_eq!(val, 0xa5);
-        val = gmem.read_obj(GuestAddress(GUEST_MEM_START + 0x0)).unwrap();
+        val = gmem.read_obj(GuestAddress(GUEST_MEM_START)).unwrap();
         assert_eq!(val, 1);
         val = gmem.read_obj(GuestAddress(GUEST_MEM_START + 0x2)).unwrap();
         assert_eq!(val, 3);
@@ -837,7 +837,7 @@ mod tests {
             size: mem_size >> 20,
             host_numa_node_id: None,
             guest_numa_node_id: Some(0),
-            vcpu_ids: cpu_vec.clone(),
+            vcpu_ids: cpu_vec,
         }];
         let mut builder = AddressSpaceMgrBuilder::new("hugeshmem", "").unwrap();
         builder.toggle_prealloc(true);
@@ -852,9 +852,9 @@ mod tests {
         assert_eq!(builder.mem_type, "shmem");
         assert_eq!(builder.mem_file, "/tmp/shmem");
         assert_eq!(builder.mem_index, 0);
-        assert_eq!(builder.mem_suffix, true);
-        assert_eq!(builder.mem_prealloc, false);
-        assert_eq!(builder.dirty_page_logging, false);
+        assert!(builder.mem_suffix);
+        assert!(!builder.mem_prealloc);
+        assert!(!builder.dirty_page_logging);
         assert!(builder.vmfd.is_none());
 
         assert_eq!(&builder.get_next_mem_file(), "/tmp/shmem0");
@@ -867,10 +867,10 @@ mod tests {
         assert_eq!(&builder.get_next_mem_file(), "/tmp/shmem");
         assert_eq!(builder.mem_index, 3);
 
-        builder.toggle_prealloc(true);
-        builder.toggle_dirty_page_logging(true);
-        assert_eq!(builder.mem_prealloc, true);
-        assert_eq!(builder.dirty_page_logging, true);
+        builder.set_prealloc(true);
+        builder.set_dirty_page_logging(true);
+        assert!(builder.mem_prealloc);
+        assert!(builder.dirty_page_logging);
     }
 
     #[test]
diff --git a/src/dragonball/src/config_manager.rs b/src/dragonball/src/config_manager.rs
index de16ab0fbf..e25b792e7b 100644
--- a/src/dragonball/src/config_manager.rs
+++ b/src/dragonball/src/config_manager.rs
@@ -178,6 +178,15 @@ where
     info_list: Vec<DeviceConfigInfo<T>>,
 }
 
+impl<T> Default for DeviceConfigInfos<T>
+where
+    T: ConfigItem + Clone,
+{
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 impl<T> DeviceConfigInfos<T>
 where
     T: ConfigItem + Clone,
@@ -221,12 +230,16 @@ where
         }
     }
 
-    #[allow(dead_code)]
     /// Get number of device configuration information objects.
     pub fn len(&self) -> usize {
         self.info_list.len()
     }
 
+    /// Returns true if the device configuration information objects is empty.
+    pub fn is_empty(&self) -> bool {
+        self.info_list.len() == 0
+    }
+
     /// Add a device configuration information object at the tail.
     pub fn push(&mut self, info: DeviceConfigInfo<T>) {
         self.info_list.push(info);
diff --git a/src/dragonball/src/device_manager/console_manager.rs b/src/dragonball/src/device_manager/console_manager.rs
index 4ebad58167..1e3b2a2f22 100644
--- a/src/dragonball/src/device_manager/console_manager.rs
+++ b/src/dragonball/src/device_manager/console_manager.rs
@@ -426,13 +426,13 @@ mod tests {
         };
 
         writer.flush().unwrap();
-        writer.write("".as_bytes()).unwrap();
-        writer.write("\n".as_bytes()).unwrap();
-        writer.write("\n\n".as_bytes()).unwrap();
-        writer.write("\n\n\n".as_bytes()).unwrap();
-        writer.write("12\n23\n34\n56".as_bytes()).unwrap();
-        writer.write("78".as_bytes()).unwrap();
-        writer.write("90\n".as_bytes()).unwrap();
+        writer.write_all("".as_bytes()).unwrap();
+        writer.write_all("\n".as_bytes()).unwrap();
+        writer.write_all("\n\n".as_bytes()).unwrap();
+        writer.write_all("\n\n\n".as_bytes()).unwrap();
+        writer.write_all("12\n23\n34\n56".as_bytes()).unwrap();
+        writer.write_all("78".as_bytes()).unwrap();
+        writer.write_all("90\n".as_bytes()).unwrap();
         writer.flush().unwrap();
     }
 
diff --git a/src/dragonball/src/vcpu/vcpu_manager.rs b/src/dragonball/src/vcpu/vcpu_manager.rs
index 189dfc6155..278a88ecea 100644
--- a/src/dragonball/src/vcpu/vcpu_manager.rs
+++ b/src/dragonball/src/vcpu/vcpu_manager.rs
@@ -784,14 +784,13 @@ impl VcpuManager {
 mod hotplug {
     use std::cmp::Ordering;
 
-    use super::*;
-    #[cfg(not(test))]
-    use dbs_upcall::CpuDevRequest;
-    use dbs_upcall::{DevMgrRequest, DevMgrResponse, UpcallClientRequest, UpcallClientResponse};
+    use dbs_upcall::{CpuDevRequest, DevMgrRequest};
 
-    #[cfg(all(target_arch = "x86_64", not(test)))]
+    use super::*;
+
+    #[cfg(all(target_arch = "x86_64"))]
     use dbs_boot::mptable::APIC_VERSION;
-    #[cfg(all(target_arch = "aarch64", not(test)))]
+    #[cfg(all(target_arch = "aarch64"))]
     const APIC_VERSION: u8 = 0;
 
     #[cfg(feature = "dbs-upcall")]
@@ -933,6 +932,9 @@ mod hotplug {
             upcall_client: Arc<UpcallClient<DevMgrService>>,
             request: DevMgrRequest,
         ) -> std::result::Result<(), VcpuManagerError> {
+            // This is used to fix clippy warnings.
+            use dbs_upcall::{DevMgrResponse, UpcallClientRequest, UpcallClientResponse};
+
             let vcpu_state_event = self.vcpu_state_event.try_clone().unwrap();
             let vcpu_state_sender = self.vcpu_state_sender.clone();