diff --git a/src/runtime/src/proto_async.rs b/src/runtime/src/proto_async.rs
index 3a35d7c..e9ee00b 100644
--- a/src/runtime/src/proto_async.rs
+++ b/src/runtime/src/proto_async.rs
@@ -51,6 +51,25 @@ pub async fn read_i32(stream: &TcpStream) -> Result<i32> {
     }).await?)
 }
 
+pub async fn read_i64(stream: &TcpStream) -> Result<i64> {
+    Ok(stream.recv(|buf| {
+        if buf.len() >= 8 {
+            let value =
+                  ((buf[0] as i64) << 56)
+                | ((buf[1] as i64) << 48)
+                | ((buf[2] as i64) << 40)
+                | ((buf[3] as i64) << 32)
+                | ((buf[4] as i64) << 24)
+                | ((buf[5] as i64) << 16)
+                | ((buf[6] as i64) << 8)
+                |  (buf[7] as i64);
+            Poll::Ready((8, value))
+        } else {
+            Poll::Pending
+        }
+    }).await?)
+}
+
 pub async fn read_chunk(stream: &TcpStream, destination: &mut [u8]) -> Result<()> {
     let total = destination.len();
     let destination = RefCell::new(destination);
diff --git a/src/runtime/src/rpc.rs b/src/runtime/src/rpc.rs
index 7fed3ed..fbaa209 100644
--- a/src/runtime/src/rpc.rs
+++ b/src/runtime/src/rpc.rs
@@ -2,16 +2,17 @@ use core::str;
 use cslice::{CSlice, CMutSlice};
 use log::debug;
 
-use core_io::{Read, Write, Error};
+use libboard_zynq::smoltcp;
+use libasync::smoltcp::TcpStream;
+use core_io::{Write, Error};
 
-use crate::proto_core_io::{ProtoRead, ProtoWrite};
+use crate::proto_core_io::ProtoWrite;
+use crate::proto_async;
 use self::tag::{Tag, TagIterator, split_tag};
 
-unsafe fn recv_value<R, E>(reader: &mut R, tag: Tag, data: &mut *mut (),
-                           alloc: &dyn Fn(usize) -> Result<*mut (), E>)
-                          -> Result<(), E>
-    where R: Read + ?Sized,
-          E: From<Error>
+async unsafe fn recv_value(stream: &TcpStream, tag: Tag<'_>, data: &mut *mut (),
+                           alloc: &dyn Fn(usize) -> *mut ())
+                          -> Result<(), smoltcp::Error>
 {
     macro_rules! consume_value {
         ($ty:ty, |$ptr:ident| $map:expr) => ({
@@ -24,22 +25,25 @@ unsafe fn recv_value<R, E>(reader: &mut R, tag: Tag, data: &mut *mut (),
     match tag {
         Tag::None => Ok(()),
         Tag::Bool =>
-            consume_value!(u8, |ptr| {
-                *ptr = reader.read_u8()?; Ok(())
+            consume_value!(i8, |ptr| {
+                *ptr = proto_async::read_i8(stream).await?;
+                Ok(())
             }),
         Tag::Int32 =>
-            consume_value!(u32, |ptr| {
-                *ptr = reader.read_u32()?; Ok(())
+            consume_value!(i32, |ptr| {
+                *ptr = proto_async::read_i32(stream).await?;
+                Ok(())
             }),
         Tag::Int64 | Tag::Float64 =>
-            consume_value!(u64, |ptr| {
-                *ptr = reader.read_u64()?; Ok(())
+            consume_value!(i64, |ptr| {
+                *ptr = proto_async::read_i64(stream).await?;
+                Ok(())
             }),
         Tag::String | Tag::Bytes | Tag::ByteArray => {
             consume_value!(CMutSlice<u8>, |ptr| {
-                let length = reader.read_u32()? as usize;
-                *ptr = CMutSlice::new(alloc(length)? as *mut u8, length);
-                reader.read_exact((*ptr).as_mut())?;
+                let length = proto_async::read_i32(stream).await? as usize;
+                *ptr = CMutSlice::new(alloc(length) as *mut u8, length);
+                proto_async::read_chunk(stream, (*ptr).as_mut()).await?;
                 Ok(())
             })
         }
@@ -47,30 +51,30 @@ unsafe fn recv_value<R, E>(reader: &mut R, tag: Tag, data: &mut *mut (),
             let mut it = it.clone();
             for _ in 0..arity {
                 let tag = it.next().expect("truncated tag");
-                recv_value(reader, tag, data, alloc)?
+                //TODO: recv_value(reader, tag, data, alloc)?
             }
             Ok(())
         }
         Tag::List(it) | Tag::Array(it) => {
             struct List { elements: *mut (), length: u32 };
             consume_value!(List, |ptr| {
-                (*ptr).length = reader.read_u32()?;
+                (*ptr).length = proto_async::read_i32(stream).await? as u32;
 
                 let tag = it.clone().next().expect("truncated tag");
-                (*ptr).elements = alloc(tag.size() * (*ptr).length as usize)?;
+                (*ptr).elements = alloc(tag.size() * (*ptr).length as usize);
 
                 let mut data = (*ptr).elements;
                 for _ in 0..(*ptr).length as usize {
-                    recv_value(reader, tag, &mut data, alloc)?
+                    //TODO: recv_value(reader, tag, &mut data, alloc).await?
                 }
                 Ok(())
             })
         }
         Tag::Range(it) => {
             let tag = it.clone().next().expect("truncated tag");
-            recv_value(reader, tag, data, alloc)?;
-            recv_value(reader, tag, data, alloc)?;
-            recv_value(reader, tag, data, alloc)?;
+            /*TODO: recv_value(reader, tag, data, alloc).await?;
+            recv_value(reader, tag, data, alloc).await?;
+            recv_value(reader, tag, data, alloc).await?;*/
             Ok(())
         }
         Tag::Keyword(_) => unreachable!(),
@@ -78,18 +82,16 @@ unsafe fn recv_value<R, E>(reader: &mut R, tag: Tag, data: &mut *mut (),
     }
 }
 
-pub fn recv_return<R, E>(reader: &mut R, tag_bytes: &[u8], data: *mut (),
-                         alloc: &dyn Fn(usize) -> Result<*mut (), E>)
-                        -> Result<(), E>
-    where R: Read + ?Sized,
-          E: From<Error>
+pub async fn recv_return(stream: &TcpStream, tag_bytes: &[u8], data: *mut (),
+                         alloc: &dyn Fn(usize) -> *mut ())
+                        -> Result<(), smoltcp::Error>
 {
     let mut it = TagIterator::new(tag_bytes);
     debug!("recv ...->{}", it);
 
     let tag = it.next().expect("truncated tag");
     let mut data = data;
-    unsafe { recv_value(reader, tag, &mut data, alloc)? };
+    unsafe { recv_value(stream, tag, &mut data, alloc).await? };
 
     Ok(())
 }