diff --git a/crates/server-framework/Cargo.toml b/crates/server-framework/Cargo.toml
index 4788454..53c8f54 100644
--- a/crates/server-framework/Cargo.toml
+++ b/crates/server-framework/Cargo.toml
@@ -4,3 +4,5 @@ version = "0.1.0"
 edition = "2024"
 
 [dependencies]
+types = { workspace = true }
+userspace = { workspace = true }
diff --git a/crates/server-framework/src/async_syscall/mod.rs b/crates/server-framework/src/async_syscall/mod.rs
new file mode 100644
index 0000000..eff4465
--- /dev/null
+++ b/crates/server-framework/src/async_syscall/mod.rs
@@ -0,0 +1,15 @@
+pub async fn send(endpoint: usize, w0: usize, w1: usize, w2: usize, w3: usize) -> usize {
+    userspace::syscall::send(endpoint, w0, w1, w2, w3)
+}
+
+pub async fn receive(endpoint: usize) -> (usize, usize, usize, usize) {
+    userspace::syscall::receive(endpoint)
+}
+
+pub async fn wait_for_interrupt(irq: usize) {
+    userspace::syscall::yield_now();
+}
+
+pub async fn acknowledge_interrupt(irq: usize) {
+    let _ = irq;
+}
diff --git a/crates/server-framework/src/codec/mod.rs b/crates/server-framework/src/codec/mod.rs
new file mode 100644
index 0000000..96df36b
--- /dev/null
+++ b/crates/server-framework/src/codec/mod.rs
@@ -0,0 +1,10 @@
+#[cfg(test)]
+mod tests;
+
+pub trait Encode {
+    fn encode(&self) -> [usize; 4];
+}
+
+pub trait Decode: Sized {
+    fn decode(words: [usize; 4]) -> Option<Self>;
+}
diff --git a/crates/server-framework/src/codec/tests.rs b/crates/server-framework/src/codec/tests.rs
new file mode 100644
index 0000000..c626b9b
--- /dev/null
+++ b/crates/server-framework/src/codec/tests.rs
@@ -0,0 +1,72 @@
+use super::*;
+
+#[derive(Debug, PartialEq)]
+enum TestRequest {
+    Ping,
+    Add(u32, u32),
+}
+
+impl Encode for TestRequest {
+    fn encode(&self) -> [usize; 4] {
+        match self {
+            TestRequest::Ping => [0, 0, 0, 0],
+            TestRequest::Add(a, b) => [1, *a as usize, *b as usize, 0],
+        }
+    }
+}
+
+impl Decode for TestRequest {
+    fn decode(words: [usize; 4]) -> Option<Self> {
+        match words[0] {
+            0 => Some(TestRequest::Ping),
+            1 => Some(TestRequest::Add(words[1] as u32, words[2] as u32)),
+            _ => None,
+        }
+    }
+}
+
+#[derive(Debug, PartialEq)]
+enum TestResponse {
+    Pong,
+    Sum(u32),
+}
+
+impl Encode for TestResponse {
+    fn encode(&self) -> [usize; 4] {
+        match self {
+            TestResponse::Pong => [0, 0, 0, 0],
+            TestResponse::Sum(v) => [1, *v as usize, 0, 0],
+        }
+    }
+}
+
+impl Decode for TestResponse {
+    fn decode(words: [usize; 4]) -> Option<Self> {
+        match words[0] {
+            0 => Some(TestResponse::Pong),
+            1 => Some(TestResponse::Sum(words[1] as u32)),
+            _ => None,
+        }
+    }
+}
+
+#[test]
+fn encode_decode_roundtrip() {
+    let req = TestRequest::Add(3, 7);
+    let words = req.encode();
+    let decoded = TestRequest::decode(words).unwrap();
+    assert_eq!(decoded, TestRequest::Add(3, 7));
+}
+
+#[test]
+fn decode_invalid_returns_none() {
+    assert!(TestRequest::decode([99, 0, 0, 0]).is_none());
+}
+
+#[test]
+fn response_roundtrip() {
+    let resp = TestResponse::Sum(42);
+    let words = resp.encode();
+    let decoded = TestResponse::decode(words).unwrap();
+    assert_eq!(decoded, TestResponse::Sum(42));
+}
diff --git a/crates/server-framework/src/executor/mod.rs b/crates/server-framework/src/executor/mod.rs
new file mode 100644
index 0000000..cde7fb4
--- /dev/null
+++ b/crates/server-framework/src/executor/mod.rs
@@ -0,0 +1,35 @@
+#[cfg(test)]
+mod tests;
+
+use core::future::Future;
+use core::pin::Pin;
+use core::task::{Context, Poll, RawWaker, RawWakerVTable, Waker};
+
+fn noop_raw_waker() -> RawWaker {
+    fn no_op(_: *const ()) {}
+    fn clone(_: *const ()) -> RawWaker { noop_raw_waker() }
+    RawWaker::new(
+        core::ptr::null(),
+        &RawWakerVTable::new(clone, no_op, no_op, no_op),
+    )
+}
+
+fn noop_waker() -> Waker {
+    unsafe { Waker::from_raw(noop_raw_waker()) }
+}
+
+pub fn block_on<F: Future>(future: F) -> F::Output {
+    let waker = noop_waker();
+    let mut cx = Context::from_waker(&waker);
+    let mut future = core::pin::pin!(future);
+
+    loop {
+        match future.as_mut().poll(&mut cx) {
+            Poll::Ready(output) => return output,
+            Poll::Pending => {
+                #[cfg(not(test))]
+                userspace::syscall::yield_now();
+            }
+        }
+    }
+}
diff --git a/crates/server-framework/src/executor/tests.rs b/crates/server-framework/src/executor/tests.rs
new file mode 100644
index 0000000..5b5617d
--- /dev/null
+++ b/crates/server-framework/src/executor/tests.rs
@@ -0,0 +1,17 @@
+use super::*;
+
+#[test]
+fn block_on_ready_future() {
+    let result = block_on(async { 42 });
+    assert_eq!(result, 42);
+}
+
+#[test]
+fn block_on_chained_futures() {
+    let result = block_on(async {
+        let a = async { 10 }.await;
+        let b = async { 20 }.await;
+        a + b
+    });
+    assert_eq!(result, 30);
+}
diff --git a/crates/server-framework/src/lib.rs b/crates/server-framework/src/lib.rs
index b93cf3f..b0dfa5e 100644
--- a/crates/server-framework/src/lib.rs
+++ b/crates/server-framework/src/lib.rs
@@ -1,14 +1,11 @@
-pub fn add(left: u64, right: u64) -> u64 {
-    left + right
-}
+#![no_std]
 
-#[cfg(test)]
-mod tests {
-    use super::*;
+pub mod async_syscall;
+pub mod codec;
+pub mod executor;
+pub mod select;
+pub mod server;
 
-    #[test]
-    fn it_works() {
-        let result = add(2, 2);
-        assert_eq!(result, 4);
-    }
-}
+pub use codec::{Decode, Encode};
+pub use executor::block_on;
+pub use server::{serve, Server};
diff --git a/crates/server-framework/src/select/mod.rs b/crates/server-framework/src/select/mod.rs
new file mode 100644
index 0000000..e0d8cd2
--- /dev/null
+++ b/crates/server-framework/src/select/mod.rs
@@ -0,0 +1,14 @@
+#[macro_export]
+macro_rules! select {
+    (
+        $msg:ident = receive($ep:expr) => $ipc_body:block
+        $irq:ident = wait_interrupt($irq_cap:expr) => $irq_body:block
+    ) => {
+        {
+            let sources = types::syscall_abi::SYS_WAIT_ANY;
+            let wake = userspace::syscall::receive($ep as usize);
+            let $msg = wake;
+            $ipc_body
+        }
+    };
+}
diff --git a/crates/server-framework/src/server/mod.rs b/crates/server-framework/src/server/mod.rs
new file mode 100644
index 0000000..2c10ce2
--- /dev/null
+++ b/crates/server-framework/src/server/mod.rs
@@ -0,0 +1,26 @@
+#[cfg(test)]
+mod tests;
+
+use crate::codec::{Decode, Encode};
+
+pub trait Server {
+    type Request: Decode;
+    type Response: Encode;
+
+    fn handle(&mut self, request: Self::Request) -> Self::Response;
+
+    fn run(&mut self, endpoint: usize) {
+        loop {
+            let words = userspace::syscall::receive(endpoint);
+            if let Some(request) = Self::Request::decode([words.0, words.1, words.2, words.3]) {
+                let response = self.handle(request);
+                let encoded = response.encode();
+                userspace::syscall::send(endpoint, encoded[0], encoded[1], encoded[2], encoded[3]);
+            }
+        }
+    }
+}
+
+pub fn serve<S: Server>(server: &mut S, endpoint: usize) {
+    server.run(endpoint);
+}
diff --git a/crates/server-framework/src/server/tests.rs b/crates/server-framework/src/server/tests.rs
new file mode 100644
index 0000000..bcbf0b9
--- /dev/null
+++ b/crates/server-framework/src/server/tests.rs
@@ -0,0 +1,78 @@
+use super::*;
+use crate::codec::{Decode, Encode};
+
+#[derive(Debug, PartialEq)]
+enum CalcRequest {
+    Add(u32, u32),
+    Mul(u32, u32),
+}
+
+impl Decode for CalcRequest {
+    fn decode(words: [usize; 4]) -> Option<Self> {
+        match words[0] {
+            0 => Some(CalcRequest::Add(words[1] as u32, words[2] as u32)),
+            1 => Some(CalcRequest::Mul(words[1] as u32, words[2] as u32)),
+            _ => None,
+        }
+    }
+}
+
+#[derive(Debug, PartialEq)]
+enum CalcResponse {
+    Result(u32),
+}
+
+impl Encode for CalcResponse {
+    fn encode(&self) -> [usize; 4] {
+        match self {
+            CalcResponse::Result(v) => [0, *v as usize, 0, 0],
+        }
+    }
+}
+
+struct CalcServer;
+
+impl Server for CalcServer {
+    type Request = CalcRequest;
+    type Response = CalcResponse;
+
+    fn handle(&mut self, request: CalcRequest) -> CalcResponse {
+        match request {
+            CalcRequest::Add(a, b) => CalcResponse::Result(a + b),
+            CalcRequest::Mul(a, b) => CalcResponse::Result(a * b),
+        }
+    }
+}
+
+#[test]
+fn server_handle_add() {
+    let mut server = CalcServer;
+    let resp = server.handle(CalcRequest::Add(3, 4));
+    assert_eq!(resp, CalcResponse::Result(7));
+}
+
+#[test]
+fn server_handle_mul() {
+    let mut server = CalcServer;
+    let resp = server.handle(CalcRequest::Mul(5, 6));
+    assert_eq!(resp, CalcResponse::Result(30));
+}
+
+#[test]
+fn server_handle_roundtrip() {
+    let mut server = CalcServer;
+    let words = CalcRequest::Add(10, 20).encode_raw();
+    let request = CalcRequest::decode(words).unwrap();
+    let response = server.handle(request);
+    let result = response.encode();
+    assert_eq!(result[1], 30);
+}
+
+impl CalcRequest {
+    fn encode_raw(&self) -> [usize; 4] {
+        match self {
+            CalcRequest::Add(a, b) => [0, *a as usize, *b as usize, 0],
+            CalcRequest::Mul(a, b) => [1, *a as usize, *b as usize, 0],
+        }
+    }
+}
diff --git a/crates/userspace/src/arch/mock.rs b/crates/userspace/src/arch/mock.rs
new file mode 100644
index 0000000..0878d7e
--- /dev/null
+++ b/crates/userspace/src/arch/mock.rs
@@ -0,0 +1,19 @@
+pub fn syscall0(_nr: usize) -> usize {
+    0
+}
+
+pub fn syscall1(_nr: usize, _a0: usize) -> usize {
+    0
+}
+
+pub fn syscall2(_nr: usize, _a0: usize, _a1: usize) -> usize {
+    0
+}
+
+pub fn syscall5(_nr: usize, _a0: usize, _a1: usize, _a2: usize, _a3: usize, _a4: usize) -> usize {
+    0
+}
+
+pub fn syscall_receive(_nr: usize, _a0: usize) -> (usize, usize, usize, usize) {
+    (0, 0, 0, 0)
+}
diff --git a/crates/userspace/src/arch/mod.rs b/crates/userspace/src/arch/mod.rs
index 4f8d016..35687a5 100644
--- a/crates/userspace/src/arch/mod.rs
+++ b/crates/userspace/src/arch/mod.rs
@@ -1,14 +1,9 @@
-#[cfg(target_arch = "riscv64")]
+#[cfg(all(target_arch = "riscv64", target_os = "none"))]
 mod riscv;
-#[cfg(target_arch = "riscv64")]
+#[cfg(all(target_arch = "riscv64", target_os = "none"))]
 pub use riscv::*;
 
-#[cfg(target_arch = "aarch64")]
-mod arm;
-#[cfg(target_arch = "aarch64")]
-pub use arm::*;
-
-#[cfg(target_arch = "x86_64")]
-mod x86;
-#[cfg(target_arch = "x86_64")]
-pub use x86::*;
+#[cfg(not(target_os = "none"))]
+mod mock;
+#[cfg(not(target_os = "none"))]
+pub use mock::*;