diff --git a/.cargo/config.toml b/.cargo/config.toml
new file mode 100644
index 0000000..bec4b7a
--- /dev/null
+++ b/.cargo/config.toml
@@ -0,0 +1,5 @@
+[build]
+target = "x86_64-unknown-mikros"
+
+[install]
+root = "../os_build/sysroot"
diff --git a/Cargo.lock b/Cargo.lock
index b4389da..068b2bc 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -13,9 +13,9 @@ dependencies = [
 
 [[package]]
 name = "autocfg"
-version = "1.1.0"
+version = "1.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d468802bab17cbc0cc575e9b053f41e72aa36bfa6b7f55e3529ffa43161b97fa"
+checksum = "ace50bade8e6234aa140d9a2f552bbee1db4d353f69b8217bc503490fc1a9f26"
 
 [[package]]
 name = "bitflags"
@@ -44,31 +44,11 @@ version = "0.2.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "67ba02a97a2bd10f4b59b25c7973101c79642302776489e030cd13cdab09ed15"
 
-[[package]]
-name = "const_format"
-version = "0.2.32"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e3a214c7af3d04997541b18d432afaff4c455e79e2029079647e72fc2bd27673"
-dependencies = [
- "const_format_proc_macros",
-]
-
-[[package]]
-name = "const_format_proc_macros"
-version = "0.2.32"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c7f6ff08fd20f4f299298a28e2dfa8a8ba1036e6cd2460ac1de7b425d76f2500"
-dependencies = [
- "proc-macro2",
- "quote",
- "unicode-xid",
-]
-
 [[package]]
 name = "critical-section"
-version = "1.1.2"
+version = "1.1.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7059fff8937831a9ae6f0fe4d658ffabf58f2ca96aa9dec1c889f936f705f216"
+checksum = "f64009896348fc5af4222e9cf7d7d82a95a256c634ebcf61c53e4ea461422242"
 
 [[package]]
 name = "embedded-io"
@@ -76,6 +56,12 @@ version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ef1a6892d9eef45c8fa6b9e0086428a2cca8491aca8f787c534a3d6d0bcb3ced"
 
+[[package]]
+name = "embedded-io"
+version = "0.6.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "edd0f118536f44f5ccd48bcb8b111bdc3de888b58c74639dfb034a357d0f206d"
+
 [[package]]
 name = "file_rpc"
 version = "0.1.0"
@@ -111,15 +97,15 @@ dependencies = [
 
 [[package]]
 name = "libc"
-version = "0.2.155"
+version = "0.2.159"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "97b3888a4aecf77e811145cadf6eef5901f4782c53886191b2f693f24761847c"
+checksum = "561d97a539a36e26a9a5fad1ea11a3039a67714694aaa379433e580854bc3dc5"
 
 [[package]]
 name = "lock_api"
-version = "0.4.8"
+version = "0.4.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9f80bf5aacaf25cbfc8210d1cfb718f2bf3b11c4c54e5afe36c236853a8ec390"
+checksum = "07af8b9cdd281b7915f413fa73f29ebd5d55d0d3f0155584dade1ff18cea1b17"
 dependencies = [
  "autocfg",
  "scopeguard",
@@ -150,13 +136,13 @@ dependencies = [
 
 [[package]]
 name = "postcard"
-version = "1.0.8"
+version = "1.0.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a55c51ee6c0db07e68448e336cf8ea4131a620edefebf9893e759b2d793420f8"
+checksum = "5f7f0a8d620d71c457dd1d47df76bb18960378da56af4527aaa10f515eee732e"
 dependencies = [
  "cobs",
- "const_format",
- "embedded-io",
+ "embedded-io 0.4.0",
+ "embedded-io 0.6.1",
  "heapless",
  "postcard-derive",
  "serde",
@@ -164,9 +150,9 @@ dependencies = [
 
 [[package]]
 name = "postcard-derive"
-version = "0.1.1"
+version = "0.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fc4b01218787dd4420daf63875163a787a78294ad48a24e9f6fa8c6507759a79"
+checksum = "0239fa9c1d225d4b7eb69925c25c5e082307a141e470573fbbe3a817ce6a7a37"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -175,45 +161,45 @@ dependencies = [
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.85"
+version = "1.0.86"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "22244ce15aa966053a896d1accb3a6e68469b97c7f33f284b99f0d576879fc23"
+checksum = "5e719e8df665df0d1c8fbfd238015744736151d4445ec0836b8e628aae103b77"
 dependencies = [
  "unicode-ident",
 ]
 
 [[package]]
 name = "quote"
-version = "1.0.36"
+version = "1.0.37"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0fa76aaf39101c457836aec0ce2316dbdc3ab723cdda1c6bd4e6ad4208acaca7"
+checksum = "b5b9d34b8991d19d98081b46eacdd8eb58c6f2b201139f7c5f643cc155a633af"
 dependencies = [
  "proc-macro2",
 ]
 
 [[package]]
 name = "redox_syscall"
-version = "0.5.1"
+version = "0.5.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "469052894dcb553421e483e4209ee581a45100d31b4018de03e5a7ad86374a7e"
+checksum = "9b6dfecf2c74bce2466cabf93f6664d6998a69eb21e39f4207930065b27b771f"
 dependencies = [
  "bitflags",
 ]
 
 [[package]]
 name = "rustc_version"
-version = "0.4.0"
+version = "0.4.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bfa0f585226d2e68097d4f95d113b15b83a82e819ab25717ec0590d9584ef366"
+checksum = "cfcb3a22ef46e85b45de6ee7e79d063319ebb6594faafcf1c225ea92ab6e9b92"
 dependencies = [
  "semver",
 ]
 
 [[package]]
 name = "scopeguard"
-version = "1.1.0"
+version = "1.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d29ab0c6d3fc0ee92fe66e2d99f700eab17a8d57d1c1d3b748380fb20baa78cd"
+checksum = "94143f37725109f92c262ed2cf5e59bce7498c01bcc1502d7b9afe439a4e9f49"
 
 [[package]]
 name = "semver"
@@ -223,22 +209,18 @@ checksum = "61697e0a1c7e512e84a621326239844a24d8207b4669b41bc18b32ea5cbf988b"
 
 [[package]]
 name = "serde"
-version = "1.0.203"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7253ab4de971e72fb7be983802300c30b5a7f0c2e56fab8abfc6a214307c0094"
+version = "1.0.210"
 dependencies = [
  "serde_derive",
 ]
 
 [[package]]
 name = "serde_derive"
-version = "1.0.203"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "500cbc0ebeb6f46627f50f3f5811ccf6bf00643be300b4c3eabc0ef55dc5b5ba"
+version = "1.0.210"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.66",
+ "syn 2.0.79",
 ]
 
 [[package]]
@@ -275,9 +257,9 @@ dependencies = [
 
 [[package]]
 name = "syn"
-version = "2.0.66"
+version = "2.0.79"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c42f3f41a2de00b01c0aaad383c5a45241efc8b2d1eda5661812fda5f3cdcff5"
+checksum = "89132cd0bf050864e1d38dc3bbc07a0eb8e7530af26344d3d2bbbef83499f590"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -286,21 +268,15 @@ dependencies = [
 
 [[package]]
 name = "unicode-ident"
-version = "1.0.3"
+version = "1.0.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c4f5b37a154999a8f3f98cc23a628d850e154479cd94decf3414696e12e31aaf"
-
-[[package]]
-name = "unicode-xid"
-version = "0.2.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f962df74c8c05a667b5ee8bcf162993134c104e96440b663c8daa176dc772d8c"
+checksum = "e91b56cd4cadaeb79bbf1a5645f6b4f8dc5bde8834ad5894a8db35fda9efa1fe"
 
 [[package]]
 name = "windows-targets"
-version = "0.52.5"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6f0713a46559409d202e70e28227288446bf7841d3211583a4b53e3f6d96e7eb"
+checksum = "9b724f72796e036ab90c1021d4780d4d3d648aca59e491e6b98e725b84e99973"
 dependencies = [
  "windows_aarch64_gnullvm",
  "windows_aarch64_msvc",
@@ -314,48 +290,48 @@ dependencies = [
 
 [[package]]
 name = "windows_aarch64_gnullvm"
-version = "0.52.5"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7088eed71e8b8dda258ecc8bac5fb1153c5cffaf2578fc8ff5d61e23578d3263"
+checksum = "32a4622180e7a0ec044bb555404c800bc9fd9ec262ec147edd5989ccd0c02cd3"
 
 [[package]]
 name = "windows_aarch64_msvc"
-version = "0.52.5"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9985fd1504e250c615ca5f281c3f7a6da76213ebd5ccc9561496568a2752afb6"
+checksum = "09ec2a7bb152e2252b53fa7803150007879548bc709c039df7627cabbd05d469"
 
 [[package]]
 name = "windows_i686_gnu"
-version = "0.52.5"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "88ba073cf16d5372720ec942a8ccbf61626074c6d4dd2e745299726ce8b89670"
+checksum = "8e9b5ad5ab802e97eb8e295ac6720e509ee4c243f69d781394014ebfe8bbfa0b"
 
 [[package]]
 name = "windows_i686_gnullvm"
-version = "0.52.5"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "87f4261229030a858f36b459e748ae97545d6f1ec60e5e0d6a3d32e0dc232ee9"
+checksum = "0eee52d38c090b3caa76c563b86c3a4bd71ef1a819287c19d586d7334ae8ed66"
 
 [[package]]
 name = "windows_i686_msvc"
-version = "0.52.5"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "db3c2bf3d13d5b658be73463284eaf12830ac9a26a90c717b7f771dfe97487bf"
+checksum = "240948bc05c5e7c6dabba28bf89d89ffce3e303022809e73deaefe4f6ec56c66"
 
 [[package]]
 name = "windows_x86_64_gnu"
-version = "0.52.5"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4e4246f76bdeff09eb48875a0fd3e2af6aada79d409d33011886d3e1581517d9"
+checksum = "147a5c80aabfbf0c7d901cb5895d1de30ef2907eb21fbbab29ca94c5b08b1a78"
 
 [[package]]
 name = "windows_x86_64_gnullvm"
-version = "0.52.5"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "852298e482cd67c356ddd9570386e2862b5673c85bd5f88df9ab6802b334c596"
+checksum = "24d5b23dc417412679681396f2b49f3de8c1473deb516bd34410872eff51ed0d"
 
 [[package]]
 name = "windows_x86_64_msvc"
-version = "0.52.5"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bec47e5bfd1bff0eeaf6d8b485cc1074891a197ab4225d504cb7a1ab88b02bf0"
+checksum = "589f6da84c646204747d1270a2a5661ea66ed1cced2631d546fdfb155959f9ec"
diff --git a/Cargo.toml b/Cargo.toml
index 59711c0..101fda0 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -9,10 +9,14 @@ edition = "2021"
 bitflags = { version = "2.6.0", features = ["serde"] }
 parking_lot = "0.12.3"
 postcard = { version = "1.0.8", features = ["experimental-derive", "use-std"] }
-serde = { version = "1.0.144" }
+serde = { path = "../serde/serde" }
 
 [profile.dev]
 panic="abort"
 
 [profile.release]
 panic="abort"
+
+[patch.crates-io]
+serde = { path = "../serde/serde" }
+serde_derive = { path = "../serde/serde_derive" }
diff --git a/rust-toolchain.toml b/rust-toolchain.toml
index 5d56faf..a5535e3 100644
--- a/rust-toolchain.toml
+++ b/rust-toolchain.toml
@@ -1,2 +1,2 @@
 [toolchain]
-channel = "nightly"
+channel = "dev-x86_64-unknown-mikros"
diff --git a/src/lib.rs b/src/lib.rs
index d4e3078..97a491a 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,8 +1,8 @@
 use std::{
-    borrow::Cow, boxed::Box, os::mikros::ipc::{
+    borrow::Cow, boxed::Box, os::mikros::{ipc::{
         self,
-        rpc::{self, CallId, IncomingCall},
-    }, vec::Vec
+        rpc::{self, CallId, IncomingCall}
+    }, Errno}, vec::Vec
 };
 
 use bitflags::bitflags;
@@ -37,11 +37,11 @@ static SERVER: RwLock<Option<Box<dyn Server>>> = RwLock::new(None);
 const PROTO: u16 = 1;
 
 pub trait Server: Send + Sync {
-    fn read<'a>(&'a self, fd: u64, len: usize) -> Result<Cow<'a, [u8]>, ()>;
-    fn write(&self, fd: u64, data: &[u8]) -> Result<(), ()>;
-    fn close(&self, fd: u64);
-    fn size(&self, fd: u64) -> Option<u64>;
-    fn dup(&self, fd: u64) -> Option<u64>;
+    fn read<'a>(&'a self, fd: u64, len: usize) -> Result<Cow<'a, [u8]>, Errno>;
+    fn write(&self, fd: u64, data: &[u8]) -> Result<(), Errno>;
+    fn close(&self, fd: u64) -> Result<(), Errno>;
+    fn size(&self, fd: u64) -> Result<u64, Errno>;
+    fn dup(&self, fd: u64) -> Result<u64, Errno>;
     fn register_poll(&self, _fd: u64, _events: PollEvents) -> u64 {
         0
     }
@@ -49,7 +49,7 @@ pub trait Server: Send + Sync {
         None
     }
     fn cancel_poll(&self, _poll_id: u64) {}
-    fn seek(&self, fd: u64, pos: SeekFrom) -> u64;
+    fn seek(&self, fd: u64, pos: SeekFrom) -> Result<u64, Errno>;
 }
 
 #[derive(Copy, Clone)]
@@ -119,7 +119,7 @@ impl Client {
         Self(pid)
     }
 
-    pub fn read(self, fd: u64, len: usize) -> Result<Vec<u8>, ()> {
+    pub fn read(self, fd: u64, len: usize) -> Result<Vec<u8>, Errno> {
         postcard::from_bytes(
             &rpc::send_call(
                 self.0,
@@ -132,7 +132,7 @@ impl Client {
         .unwrap()
     }
 
-    pub fn write(self, fd: u64, data: &[u8]) -> Result<(), ()> {
+    pub fn write(self, fd: u64, data: &[u8]) -> Result<(), Errno> {
         postcard::from_bytes(
             &rpc::send_call(
                 self.0,
@@ -145,21 +145,21 @@ impl Client {
         .unwrap()
     }
 
-    pub fn close(self, fd: u64) {
+    pub fn close(self, fd: u64) -> Result<(), Errno> {
         postcard::from_bytes(
             &rpc::send_call(self.0, PROTO, 2, &postcard::to_stdvec(&fd).unwrap()).get_return(),
         )
         .unwrap()
     }
 
-    pub fn size(self, fd: u64) -> Option<u64> {
+    pub fn size(self, fd: u64) -> Result<u64, Errno> {
         postcard::from_bytes(
             &rpc::send_call(self.0, PROTO, 3, &postcard::to_stdvec(&fd).unwrap()).get_return(),
         )
         .unwrap()
     }
 
-    pub fn dup(self, fd: u64) -> Option<u64> {
+    pub fn dup(self, fd: u64) -> Result<u64, Errno> {
         postcard::from_bytes(
             &rpc::send_call(self.0, PROTO, 4, &postcard::to_stdvec(&fd).unwrap()).get_return(),
         )
@@ -185,7 +185,7 @@ impl Client {
         }
     }
 
-    pub fn seek(&self, fd: u64, pos: SeekFrom) -> u64 {
+    pub fn seek(&self, fd: u64, pos: SeekFrom) -> Result<u64, Errno> {
         postcard::from_bytes(
             &rpc::send_call(self.0, PROTO, 8, &postcard::to_stdvec(&(fd, pos)).unwrap()).get_return(),
         )