diff --git a/vmm/src/api/openapi/cloud-hypervisor.yaml b/vmm/src/api/openapi/cloud-hypervisor.yaml
index a92af5ca9..c8e059da9 100644
--- a/vmm/src/api/openapi/cloud-hypervisor.yaml
+++ b/vmm/src/api/openapi/cloud-hypervisor.yaml
@@ -321,9 +321,13 @@ components:
           type: integer
         queue_size:
           type: integer
+        dax:
+          type: boolean
+          default: true
         cache_size:
           type: integer
           format: int64
+          default: 8589934592
 
     PmemConfig:
       required:
diff --git a/vmm/src/config.rs b/vmm/src/config.rs
index 0ed5d90f4..10024f5f5 100644
--- a/vmm/src/config.rs
+++ b/vmm/src/config.rs
@@ -409,7 +409,8 @@ pub struct FsConfig {
     pub sock: PathBuf,
     pub num_queues: usize,
     pub queue_size: u16,
-    pub cache_size: Option<u64>,
+    pub dax: bool,
+    pub cache_size: u64,
 }
 
 impl FsConfig {
@@ -444,7 +445,7 @@ impl FsConfig {
         let mut queue_size: u16 = 1024;
         let mut dax: bool = true;
         // Default cache size set to 8Gib.
-        let mut cache_size: Option<u64> = Some(0x0002_0000_0000);
+        let mut cache_size: u64 = 0x0002_0000_0000;
 
         if tag.is_empty() {
             return Err(Error::ParseFsTagParam);
@@ -476,9 +477,9 @@ impl FsConfig {
             if !cache_size_str.is_empty() {
                 return Err(Error::InvalidCacheSizeWithDaxOff);
             }
-            cache_size = None;
+            cache_size = 0;
         } else if !cache_size_str.is_empty() {
-            cache_size = Some(parse_size(cache_size_str)?);
+            cache_size = parse_size(cache_size_str)?;
         }
 
         Ok(FsConfig {
@@ -486,6 +487,7 @@ impl FsConfig {
             sock: PathBuf::from(sock),
             num_queues,
             queue_size,
+            dax,
             cache_size,
         })
     }
diff --git a/vmm/src/device_manager.rs b/vmm/src/device_manager.rs
index 3edfa15a9..cd6d18586 100644
--- a/vmm/src/device_manager.rs
+++ b/vmm/src/device_manager.rs
@@ -958,8 +958,8 @@ impl DeviceManager {
         if let Some(fs_list_cfg) = &vm_info.vm_cfg.lock().unwrap().fs {
             for fs_cfg in fs_list_cfg.iter() {
                 if let Some(fs_sock) = fs_cfg.sock.to_str() {
-                    let mut cache: Option<(VirtioSharedMemoryList, u64)> = None;
-                    if let Some(fs_cache) = fs_cfg.cache_size {
+                    let cache: Option<(VirtioSharedMemoryList, u64)> = if fs_cfg.dax {
+                        let fs_cache = fs_cfg.cache_size;
                         // The memory needs to be 2MiB aligned in order to support
                         // hugepages.
                         let fs_guest_addr = allocator
@@ -1004,15 +1004,18 @@ impl DeviceManager {
                             offset: 0,
                             len: fs_cache,
                         });
-                        cache = Some((
+
+                        Some((
                             VirtioSharedMemoryList {
                                 addr: fs_guest_addr,
                                 len: fs_cache as GuestUsize,
                                 region_list,
                             },
                             addr as u64,
-                        ));
-                    }
+                        ))
+                    } else {
+                        None
+                    };
 
                     let virtio_fs_device = vm_virtio::vhost_user::Fs::new(
                         fs_sock,