diff --git a/kernel/aster-nix/src/process/process_vm/init_stack/mod.rs b/kernel/aster-nix/src/process/process_vm/init_stack/mod.rs
index 0ea09d292..216b8e436 100644
--- a/kernel/aster-nix/src/process/process_vm/init_stack/mod.rs
+++ b/kernel/aster-nix/src/process/process_vm/init_stack/mod.rs
@@ -115,7 +115,7 @@ impl Clone for InitStack {
             initial_top: self.initial_top,
             max_size: self.max_size,
             pos: self.pos.clone(),
-            vmo: self.vmo.new_cow_child(0..self.max_size).alloc().unwrap(),
+            vmo: self.vmo.dup(),
         }
     }
 }
@@ -149,8 +149,9 @@ impl InitStack {
             let map_addr = self.initial_top - self.max_size;
             debug_assert!(map_addr % PAGE_SIZE == 0);
             root_vmar
-                .new_map(self.vmo.dup().to_dyn(), perms)?
+                .new_map(self.max_size, perms)?
                 .offset(map_addr)
+                .vmo(self.vmo.dup().to_dyn())
         };
 
         vmar_map_options.build()?;
diff --git a/kernel/aster-nix/src/vm/vmar/dyn_cap.rs b/kernel/aster-nix/src/vm/vmar/dyn_cap.rs
index 7d503ace5..a660cf2bc 100644
--- a/kernel/aster-nix/src/vm/vmar/dyn_cap.rs
+++ b/kernel/aster-nix/src/vm/vmar/dyn_cap.rs
@@ -3,15 +3,11 @@
 use core::ops::Range;
 
 use aster_rights::Rights;
-use ostd::mm::VmIo;
 
 use super::{
     options::VmarChildOptions, vm_mapping::VmarMapOptions, VmPerms, Vmar, VmarRightsOp, Vmar_,
 };
-use crate::{
-    prelude::*,
-    vm::{page_fault_handler::PageFaultHandler, vmo::Vmo},
-};
+use crate::{prelude::*, vm::page_fault_handler::PageFaultHandler};
 
 impl Vmar<Rights> {
     /// Creates a root VMAR.
@@ -21,7 +17,7 @@ impl Vmar<Rights> {
         Self(inner, rights)
     }
 
-    /// Maps the given VMO into the VMAR through a set of VMAR mapping options.
+    /// Creates a mapping into the VMAR through a set of VMAR mapping options.
     ///
     /// # Example
     ///
@@ -30,13 +26,18 @@ impl Vmar<Rights> {
     /// use aster_nix::vm::{PAGE_SIZE, Vmar, VmoOptions};
     ///
     /// let vmar = Vmar::new().unwrap();
-    /// let vmo = VmoOptions::new(PAGE_SIZE).alloc().unwrap();
+    /// let vmo = VmoOptions::new(10 * PAGE_SIZE).alloc().unwrap();
     /// let target_vaddr = 0x1234000;
     /// let real_vaddr = vmar
-    ///     // Map the VMO to create a read-only mapping
-    ///     .new_map(vmo, VmPerms::READ)
+    ///     // Create a 4 * PAGE_SIZE bytes, read-only mapping
+    ///     .new_map(PAGE_SIZE * 4, VmPerms::READ)
     ///     // Provide an optional offset for the mapping inside the VMAR
     ///     .offset(target_vaddr)
+    ///     // Specify an optional binding VMO.
+    ///     .vmo(vmo)
+    ///     // Provide an optional offset to indicate the corresponding offset
+    ///     // in the VMO for the mapping
+    ///     .vmo_offset(2 * PAGE_SIZE)
     ///     .build()
     ///     .unwrap();
     /// assert!(real_vaddr == target_vaddr);
@@ -56,13 +57,9 @@ impl Vmar<Rights> {
     /// Memory permissions may be changed through the `protect` method,
     /// which ensures that any updated memory permissions do not go beyond
     /// the access rights of the underlying VMOs.
-    pub fn new_map(
-        &self,
-        vmo: Vmo<Rights>,
-        perms: VmPerms,
-    ) -> Result<VmarMapOptions<Rights, Rights>> {
+    pub fn new_map(&self, size: usize, perms: VmPerms) -> Result<VmarMapOptions<Rights, Rights>> {
         let dup_self = self.dup()?;
-        Ok(VmarMapOptions::new(dup_self, vmo, perms))
+        Ok(VmarMapOptions::new(dup_self, size, perms))
     }
 
     /// Creates a new child VMAR through a set of VMAR child options.
@@ -98,10 +95,6 @@ impl Vmar<Rights> {
     ///
     /// The VMAR must have the rights corresponding to the specified memory
     /// permissions.
-    ///
-    /// The mappings overlapped with the specified range must be backed by
-    /// VMOs whose rights contain the rights corresponding to the specified
-    /// memory permissions.
     pub fn protect(&self, perms: VmPerms, range: Range<usize>) -> Result<()> {
         self.check_rights(perms.into())?;
         self.0.protect(perms, range)
@@ -150,20 +143,6 @@ impl Vmar<Rights> {
     }
 }
 
-impl VmIo for Vmar<Rights> {
-    fn read_bytes(&self, offset: usize, buf: &mut [u8]) -> ostd::Result<()> {
-        self.check_rights(Rights::READ)?;
-        self.0.read(offset, buf)?;
-        Ok(())
-    }
-
-    fn write_bytes(&self, offset: usize, buf: &[u8]) -> ostd::Result<()> {
-        self.check_rights(Rights::WRITE)?;
-        self.0.write(offset, buf)?;
-        Ok(())
-    }
-}
-
 impl PageFaultHandler for Vmar<Rights> {
     fn handle_page_fault(
         &self,
diff --git a/kernel/aster-nix/src/vm/vmar/options.rs b/kernel/aster-nix/src/vm/vmar/options.rs
index ac0fa7b10..95f9cd4d1 100644
--- a/kernel/aster-nix/src/vm/vmar/options.rs
+++ b/kernel/aster-nix/src/vm/vmar/options.rs
@@ -179,22 +179,12 @@ mod test {
         let map_offset = 0x1000_0000;
         let vmo_dup = vmo.dup().unwrap();
         root_vmar
-            .new_map(vmo_dup, perms)
+            .new_map(PAGE_SIZE, perms)
             .unwrap()
+            .vmo(vmo_dup)
             .offset(map_offset)
             .build()
             .unwrap();
-        root_vmar.write_val(map_offset, &100u8).unwrap();
-        assert!(root_vmar.read_val::<u8>(map_offset).unwrap() == 100);
-        let another_map_offset = 0x1100_0000;
-        let vmo_dup = vmo.dup().unwrap();
-        root_vmar
-            .new_map(vmo_dup, perms)
-            .unwrap()
-            .offset(another_map_offset)
-            .build()
-            .unwrap();
-        assert!(root_vmar.read_val::<u8>(another_map_offset).unwrap() == 100);
     }
 
     #[ktest]
@@ -208,8 +198,9 @@ mod test {
         let perms = VmPerms::READ;
         let vmo_dup = vmo.dup().unwrap();
         root_vmar
-            .new_map(vmo_dup, perms)
+            .new_map(PAGE_SIZE, perms)
             .unwrap()
+            .vmo(vmo_dup)
             .offset(OFFSET)
             .build()
             .unwrap();
diff --git a/kernel/aster-nix/src/vm/vmar/static_cap.rs b/kernel/aster-nix/src/vm/vmar/static_cap.rs
index 120383f6f..25653fb8f 100644
--- a/kernel/aster-nix/src/vm/vmar/static_cap.rs
+++ b/kernel/aster-nix/src/vm/vmar/static_cap.rs
@@ -4,15 +4,11 @@ use core::ops::Range;
 
 use aster_rights::{Dup, Rights, TRightSet, TRights};
 use aster_rights_proc::require;
-use ostd::mm::VmIo;
 
 use super::{
     options::VmarChildOptions, vm_mapping::VmarMapOptions, VmPerms, Vmar, VmarRightsOp, Vmar_,
 };
-use crate::{
-    prelude::*,
-    vm::{page_fault_handler::PageFaultHandler, vmo::Vmo},
-};
+use crate::{prelude::*, vm::page_fault_handler::PageFaultHandler};
 
 impl<R: TRights> Vmar<TRightSet<R>> {
     /// Creates a root VMAR.
@@ -26,7 +22,7 @@ impl<R: TRights> Vmar<TRightSet<R>> {
         Self(inner, TRightSet(rights))
     }
 
-    /// Maps the given VMO into the VMAR through a set of VMAR mapping options.
+    /// Creates a mapping into the VMAR through a set of VMAR mapping options.
     ///
     /// # Example
     ///
@@ -35,13 +31,18 @@ impl<R: TRights> Vmar<TRightSet<R>> {
     /// use aster_nix::vm::{PAGE_SIZE, Vmar, VmoOptions};
     ///
     /// let vmar = Vmar::<RightsWrapper<Full>>::new().unwrap();
-    /// let vmo = VmoOptions::new(PAGE_SIZE).alloc().unwrap();
+    /// let vmo = VmoOptions::new(10 * PAGE_SIZE).alloc().unwrap();
     /// let target_vaddr = 0x1234000;
     /// let real_vaddr = vmar
-    ///     // Map the VMO to create a read-only mapping
-    ///     .new_map(vmo, VmPerms::READ)
+    ///     // Create a 4 * PAGE_SIZE bytes, read-only mapping
+    ///     .new_map(PAGE_SIZE * 4, VmPerms::READ)
     ///     // Provide an optional offset for the mapping inside the VMAR
     ///     .offset(target_vaddr)
+    ///     // Specify an optional binding VMO.
+    ///     .vmo(vmo)
+    ///     // Provide an optional offset to indicate the corresponding offset
+    ///     // in the VMO for the mapping
+    ///     .vmo_offset(2 * PAGE_SIZE)
     ///     .build()
     ///     .unwrap();
     /// assert!(real_vaddr == target_vaddr);
@@ -64,11 +65,11 @@ impl<R: TRights> Vmar<TRightSet<R>> {
     #[require(R > Dup)]
     pub fn new_map(
         &self,
-        vmo: Vmo<Rights>,
+        size: usize,
         perms: VmPerms,
     ) -> Result<VmarMapOptions<TRightSet<R>, Rights>> {
         let dup_self = self.dup()?;
-        Ok(VmarMapOptions::new(dup_self, vmo, perms))
+        Ok(VmarMapOptions::new(dup_self, size, perms))
     }
 
     /// Creates a new child VMAR through a set of VMAR child options.
@@ -105,10 +106,6 @@ impl<R: TRights> Vmar<TRightSet<R>> {
     ///
     /// The VMAR must have the rights corresponding to the specified memory
     /// permissions.
-    ///
-    /// The mappings overlapped with the specified range must be backed by
-    /// VMOs whose rights contain the rights corresponding to the specified
-    /// memory permissions.
     pub fn protect(&self, perms: VmPerms, range: Range<usize>) -> Result<()> {
         self.check_rights(perms.into())?;
         self.0.protect(perms, range)
@@ -171,20 +168,6 @@ impl<R: TRights> Vmar<TRightSet<R>> {
     }
 }
 
-impl<R: TRights> VmIo for Vmar<TRightSet<R>> {
-    fn read_bytes(&self, offset: usize, buf: &mut [u8]) -> ostd::Result<()> {
-        self.check_rights(Rights::READ)?;
-        self.0.read(offset, buf)?;
-        Ok(())
-    }
-
-    fn write_bytes(&self, offset: usize, buf: &[u8]) -> ostd::Result<()> {
-        self.check_rights(Rights::WRITE)?;
-        self.0.write(offset, buf)?;
-        Ok(())
-    }
-}
-
 impl<R: TRights> PageFaultHandler for Vmar<TRightSet<R>> {
     fn handle_page_fault(
         &self,