diff --git a/luisa_compute/examples/polymorphism.rs b/luisa_compute/examples/polymorphism.rs
index 4ed1d5d..788b695 100644
--- a/luisa_compute/examples/polymorphism.rs
+++ b/luisa_compute/examples/polymorphism.rs
@@ -34,7 +34,17 @@ impl Area for SquareExpr {
 impl_polymorphic!(Area, Square);
 fn main() {
     let ctx = Context::new(current_exe().unwrap());
-    let device = ctx.create_device("cpu");
+    let args: Vec<String> = std::env::args().collect();
+    assert!(
+        args.len() <= 2,
+        "Usage: {} <backend>. <backend>: cpu, cuda, dx, metal, remote",
+        args[0]
+    );
+    let device = ctx.create_device(if args.len() == 2 {
+        args[1].as_str()
+    } else {
+        "cpu"
+    });
     let circles = device.create_buffer::<Circle>(2);
     circles
         .view(..)
diff --git a/luisa_compute/src/resource.rs b/luisa_compute/src/resource.rs
index 08a579f..a228d50 100644
--- a/luisa_compute/src/resource.rs
+++ b/luisa_compute/src/resource.rs
@@ -1397,6 +1397,27 @@ impl<T: Value> IndexRead for BindlessBufferVar<T> {
         }))
     }
 }
+impl<T: Value> IndexWrite for BindlessBufferVar<T> {
+    fn write<I: IntoIndex, V: AsExpr<Value = Self::Element>>(&self, i: I, value: V) {
+        let i = i.to_u64();
+        if need_runtime_check() {
+            lc_assert!(i.lt(self.len_expr()));
+        }
+        let value = value.as_expr();
+        __current_scope(|b| {
+            b.call(
+                Func::BindlessBufferWrite,
+                &[
+                    self.array,
+                    self.buffer_index.node(),
+                    ToNode::node(&i),
+                    value.node(),
+                ],
+                Type::void(),
+            )
+        });
+    }
+}
 impl<T: Value> BindlessBufferVar<T> {
     pub fn len_expr(&self) -> Expr<u64> {
         let stride = (T::type_().size() as u64).expr();
@@ -1789,6 +1810,11 @@ impl<T: Value> BufferVar<T> {
             __current_scope(|b| b.call(Func::BufferSize, &[self.node], u64::type_())).into(),
         )
     }
+    pub fn len_expr_u32(&self) -> Expr<u32> {
+        FromNode::from_node(
+            __current_scope(|b| b.call(Func::BufferSize, &[self.node], u32::type_())).into(),
+        )
+    }
 }
 
 macro_rules! impl_atomic {
diff --git a/luisa_compute/src/runtime.rs b/luisa_compute/src/runtime.rs
index 182a085..2ad0783 100644
--- a/luisa_compute/src/runtime.rs
+++ b/luisa_compute/src/runtime.rs
@@ -175,6 +175,13 @@ impl Device {
         swapchain
     }
     pub fn create_byte_buffer(&self, len: usize) -> Buffer<u8> {
+        let name = self.name();
+        if name == "dx" {
+            assert!(
+                len < u32::MAX as usize,
+                "numer of bytes must be less than u32::MAX on dx"
+            );
+        }
         let buffer = self.inner.create_buffer(&Type::void(), len);
         let buffer = Buffer {
             device: self.clone(),
@@ -199,6 +206,10 @@ impl Device {
                 std::mem::align_of::<T>() >= 4,
                 "T must be aligned to 4 bytes on dx"
             );
+            assert!(
+                count < u32::MAX as usize,
+                "count must be less than u32::MAX on dx"
+            );
         }
         assert!(
             std::mem::size_of::<T>() > 0,
diff --git a/luisa_compute/tests/misc.rs b/luisa_compute/tests/misc.rs
index dd32337..ceab4f2 100644
--- a/luisa_compute/tests/misc.rs
+++ b/luisa_compute/tests/misc.rs
@@ -874,7 +874,7 @@ fn uniform() {
     let expected = (x.len() as f32 - 1.0) * x.len() as f32 * 0.5 * 6.0;
     assert!((actual - expected).abs() < 1e-4);
 }
-#[derive(Clone, Copy, Debug, Value)]
+#[derive(Clone, Copy, Debug, Value, Default)]
 #[repr(C)]
 struct Big {
     a: [f32; 32],
@@ -1279,6 +1279,27 @@ fn dispatch_async() {
     drop(kernel);
 }
 
+#[test]
+fn buffer_size() {
+    let device = get_device();
+    let x = device.create_buffer::<Big>(1024);
+    x.fill(Big::default());
+    let out = device.create_buffer::<u32>(1);
+    out.fill(2);
+    device
+        .create_kernel::<fn()>(&track!(|| {
+            lc_assert!((x.len() as u64).eq(x.var().len_expr()));
+            lc_assert!((x.len() as u32).eq(x.var().len_expr().cast_u32()));
+            let tid = dispatch_id().x;
+            if tid == 0 {
+                out.write(0, x.var().len_expr_u32());
+            }
+        }))
+        .dispatch([1024, 1, 1]);
+    let out = out.view(..).copy_to_vec();
+    assert_eq!(out[0], 1024);
+}
+
 #[test]
 #[tracked]
 fn test_tracked() {
diff --git a/luisa_compute_sys/LuisaCompute b/luisa_compute_sys/LuisaCompute
index c291315..1b2b323 160000
--- a/luisa_compute_sys/LuisaCompute
+++ b/luisa_compute_sys/LuisaCompute
@@ -1 +1 @@
-Subproject commit c2913151806bbe6175ef06692283bc85804e469f
+Subproject commit 1b2b3238d2596ba0b8337f72e82a7d7640253d0b