fix satman error traits

src/libboard_artiq/src/drtioaux.rs

@@ -9,7 +9,7 @@ pub use crate::drtioaux_proto::Packet;
 use crate::{drtioaux_proto::Error as ProtocolError, mem::mem::DRTIOAUX_MEM, pl::csr::DRTIOAUX};
 
 #[derive(Debug)]
-pub enum Error {
+pub enum Error<T> {
     GatewareError,
     CorruptedPacket,
 
@@ -19,17 +19,17 @@ pub enum Error {
 
     RoutingError,
 
-    Protocol(ProtocolError),
+    Protocol(ProtocolError<T>),
 }
 
-impl From<ProtocolError> for Error {
+impl<T> From<ProtocolError<T>> for Error<T> {
-    fn from(value: ProtocolError) -> Error {
+    fn from(value: ProtocolError<T>) -> Error<T> {
         Error::Protocol(value)
     }
 }
 
-impl From<IoError> for Error {
+impl<T> From<IoError<T>> for Error<T> {
-    fn from(value: IoError) -> Error {
+    fn from(value: IoError<T>) -> Error<T> {
         Error::Protocol(ProtocolError::Io(value))
     }
 }
@@ -56,8 +56,8 @@ pub fn has_rx_error(linkno: u8) -> bool {
     }
 }
 
-fn receive<F, T>(linkno: u8, f: F) -> Result<Option<T>, Error>
+fn receive<F, T>(linkno: u8, f: F) -> Result<Option<T>, Error<!>>
-where F: FnOnce(&[u8]) -> Result<T, Error> {
+where F: FnOnce(&[u8]) -> Result<T, Error<!>> {
     let linkidx = linkno as usize;
     unsafe {
         if (DRTIOAUX[linkidx].aux_rx_present_read)() == 1 {
@@ -72,14 +72,14 @@ where F: FnOnce(&[u8]) -> Result<T, Error> {
     }
 }
 
-pub fn recv(linkno: u8) -> Result<Option<Packet>, Error> {
+pub fn recv(linkno: u8) -> Result<Option<Packet>, Error<!>> {
     if has_rx_error(linkno) {
         return Err(Error::GatewareError);
     }
 
     receive(linkno, |buffer| {
         if buffer.len() < 8 {
-            return Err(IoError::UnexpectedEnd).into());
+            return Err(IoError::UnexpectedEnd.into());
         }
 
         let mut reader = Cursor::new(buffer);
@@ -96,7 +96,7 @@ pub fn recv(linkno: u8) -> Result<Option<Packet>, Error> {
     })
 }
 
-pub fn recv_timeout(linkno: u8, timeout_ms: Option<u64>, timer: GlobalTimer) -> Result<Packet, Error> {
+pub fn recv_timeout(linkno: u8, timeout_ms: Option<u64>, timer: GlobalTimer) -> Result<Packet, Error<!>> {
     let timeout_ms = Milliseconds(timeout_ms.unwrap_or(10));
     let limit = timer.get_time() + timeout_ms;
     while timer.get_time() < limit {
@@ -108,8 +108,8 @@ pub fn recv_timeout(linkno: u8, timeout_ms: Option<u64>, timer: GlobalTimer) ->
     Err(Error::TimedOut)
 }
 
-fn transmit<F>(linkno: u8, f: F) -> Result<(), Error>
+fn transmit<F>(linkno: u8, f: F) -> Result<(), Error<!>>
-where F: FnOnce(&mut [u8]) -> Result<usize, Error> {
+where F: FnOnce(&mut [u8]) -> Result<usize, Error<!>> {
     let linkno = linkno as usize;
     unsafe {
         while (DRTIOAUX[linkno].aux_tx_read)() != 0 {}
@@ -121,7 +121,7 @@ where F: FnOnce(&mut [u8]) -> Result<usize, Error> {
     }
 }
 
-pub fn send(linkno: u8, packet: &Packet) -> Result<(), Error> {
+pub fn send(linkno: u8, packet: &Packet) -> Result<(), Error<!>> {
     transmit(linkno, |buffer| {
         let mut writer = Cursor::new(buffer);
 

src/libboard_artiq/src/drtioaux_async.rs

@@ -34,8 +34,8 @@ fn tx_ready(linkno: usize) -> nb::Result<(), Void> {
     }
 }
 
-async fn receive<F, T>(linkno: u8, f: F) -> Result<Option<T>, Error>
+async fn receive<F, T>(linkno: u8, f: F) -> Result<Option<T>, Error<!>>
-where F: FnOnce(&[u8]) -> Result<T, Error> {
+where F: FnOnce(&[u8]) -> Result<T, Error<!>> {
     let linkidx = linkno as usize;
     unsafe {
         if (DRTIOAUX[linkidx].aux_rx_present_read)() == 1 {
@@ -50,14 +50,14 @@ where F: FnOnce(&[u8]) -> Result<T, Error> {
     }
 }
 
-pub async fn recv(linkno: u8) -> Result<Option<Packet>, Error> {
+pub async fn recv(linkno: u8) -> Result<Option<Packet>, Error<!>> {
     if has_rx_error(linkno) {
         return Err(Error::GatewareError);
     }
 
     receive(linkno, |buffer| {
         if buffer.len() < 8 {
-            return Err(IoError::UnexpectedEnd).into());
+            return Err(IoError::UnexpectedEnd.into());
         }
 
         let mut reader = Cursor::new(buffer);
@@ -75,7 +75,7 @@ pub async fn recv(linkno: u8) -> Result<Option<Packet>, Error> {
     .await
 }
 
-pub async fn recv_timeout(linkno: u8, timeout_ms: Option<u64>, timer: GlobalTimer) -> Result<Packet, Error> {
+pub async fn recv_timeout(linkno: u8, timeout_ms: Option<u64>, timer: GlobalTimer) -> Result<Packet, Error<!>> {
     let timeout_ms = Milliseconds(timeout_ms.unwrap_or(10));
     let limit = timer.get_time() + timeout_ms;
     let mut would_block = false;
@@ -95,8 +95,8 @@ pub async fn recv_timeout(linkno: u8, timeout_ms: Option<u64>, timer: GlobalTime
     Err(Error::TimedOut)
 }
 
-async fn transmit<F>(linkno: u8, f: F) -> Result<(), Error>
+async fn transmit<F>(linkno: u8, f: F) -> Result<(), Error<!>>
-where F: FnOnce(&mut [u8]) -> Result<usize, Error> {
+where F: FnOnce(&mut [u8]) -> Result<usize, Error<!>> {
     let linkno = linkno as usize;
     unsafe {
         let _ = block_async!(tx_ready(linkno)).await;
@@ -108,7 +108,7 @@ where F: FnOnce(&mut [u8]) -> Result<usize, Error> {
     }
 }
 
-pub async fn send(linkno: u8, packet: &Packet) -> Result<(), Error> {
+pub async fn send(linkno: u8, packet: &Packet) -> Result<(), Error<!>> {
     transmit(linkno, |buffer| {
         let mut writer = Cursor::new(buffer);
 

src/libksupport/src/rpc.rs

@@ -44,7 +44,7 @@ unsafe fn recv_elements<F, R, E>(
     alloc: &mut F,
 ) -> Result<(), E>
 where
-    F: FnMut(usize) -> *mut (),
+    F: FnMut(usize) -> Result<*mut (), E>,
     R: Read + ?Sized,
     E: From<Error<R::ReadError>>,
 {
@@ -81,7 +81,7 @@ where
 
 unsafe fn recv_value<F, R, E>(reader: &mut R, tag: Tag, data: &mut *mut (), alloc: &mut F) -> Result<(), E>
 where
-    F: FnMut(usize) -> *mut (),
+    F: FnMut(usize) -> Result<*mut (), E>,
     R: Read + ?Sized,
     E: From<Error<R::ReadError>>,
 {
@@ -110,7 +110,7 @@ where
         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);
+                *ptr = CMutSlice::new(alloc(length)? as *mut u8, length);
                 reader.read_exact((*ptr).as_mut())?;
                 Ok(())
             })
@@ -140,7 +140,7 @@ where
                 let storage_offset = round_up(list_size, tag.alignment());
                 let storage_size = tag.size() * length;
 
-                let allocation = alloc(storage_offset + storage_size) as *mut u8;
+                let allocation = alloc(storage_offset + storage_size)? as *mut u8;
                 *ptr_to_list = allocation as *mut List;
                 let storage = allocation.offset(storage_offset as isize) as *mut ();
 
@@ -159,7 +159,7 @@ where
                 }
 
                 let elt_tag = it.clone().next().expect("truncated tag");
-                *buffer = alloc(elt_tag.size() * total_len);
+                *buffer = alloc(elt_tag.size() * total_len)?;
                 recv_elements(reader, elt_tag, total_len, *buffer, alloc)
             })
         }
@@ -183,7 +183,7 @@ pub fn recv_return<'a, F, R, E>(
     alloc: &mut F,
 ) -> Result<&'a [u8], E>
 where
-    F: FnMut(usize) -> *mut (),
+    F: FnMut(usize) -> Result<*mut (), E>,
     R: Read + ?Sized,
     E: From<Error<R::ReadError>>,
 {

src/satman/src/main.rs

@@ -1,6 +1,6 @@
 #![no_std]
 #![no_main]
-#![feature(alloc_error_handler, try_trait, never_type, panic_info_message)]
+#![feature(alloc_error_handler, never_type)]
 
 #[macro_use]
 extern crate log;
@@ -149,7 +149,7 @@ fn process_aux_packet(
     analyzer: &mut Analyzer,
     kernel_manager: &mut KernelManager,
     router: &mut Router,
-) -> Result<(), drtioaux::Error> {
+) -> Result<(), drtioaux::Error<!>> {
     // In the code below, *_chan_sel_write takes an u8 if there are fewer than 256 channels,
     // and u16 otherwise; hence the `as _` conversion.
     match packet {

src/satman/src/repeater.rs

@@ -191,7 +191,7 @@ impl Repeater {
         }
     }
 
-    fn recv_aux_timeout(&self, timeout: u32, timer: &mut GlobalTimer) -> Result<drtioaux::Packet, drtioaux::Error> {
+    fn recv_aux_timeout(&self, timeout: u32, timer: &mut GlobalTimer) -> Result<drtioaux::Packet, drtioaux::Error<!>> {
         let max_time = timer.get_time() + Milliseconds(timeout.into());
         loop {
             if !rep_link_rx_up(self.repno) {
@@ -216,7 +216,7 @@ impl Repeater {
         rank: u8,
         self_destination: u8,
         timer: &mut GlobalTimer,
-    ) -> Result<(), drtioaux::Error> {
+    ) -> Result<(), drtioaux::Error<!>> {
         self.aux_send(request)?;
         loop {
             let reply = self.recv_aux_timeout(200, timer)?;
@@ -242,14 +242,14 @@ impl Repeater {
         Ok(())
     }
 
-    pub fn aux_send(&self, request: &drtioaux::Packet) -> Result<(), drtioaux::Error> {
+    pub fn aux_send(&self, request: &drtioaux::Packet) -> Result<(), drtioaux::Error<!>> {
         if self.state != RepeaterState::Up {
             return Err(drtioaux::Error::LinkDown);
         }
         drtioaux::send(self.auxno, request)
     }
 
-    pub fn sync_tsc(&self, timer: &mut GlobalTimer) -> Result<(), drtioaux::Error> {
+    pub fn sync_tsc(&self, timer: &mut GlobalTimer) -> Result<(), drtioaux::Error<!>> {
         if self.state != RepeaterState::Up {
             return Ok(());
         }
@@ -275,7 +275,7 @@ impl Repeater {
         destination: u8,
         hops: &[u8; drtio_routing::MAX_HOPS],
         timer: &mut GlobalTimer,
-    ) -> Result<(), drtioaux::Error> {
+    ) -> Result<(), drtioaux::Error<!>> {
         if self.state != RepeaterState::Up {
             return Ok(());
         }
@@ -299,14 +299,14 @@ impl Repeater {
         &self,
         routing_table: &drtio_routing::RoutingTable,
         timer: &mut GlobalTimer,
-    ) -> Result<(), drtioaux::Error> {
+    ) -> Result<(), drtioaux::Error<!>> {
         for i in 0..drtio_routing::DEST_COUNT {
             self.set_path(i as u8, &routing_table.0[i], timer)?;
         }
         Ok(())
     }
 
-    pub fn set_rank(&self, rank: u8, timer: &mut GlobalTimer) -> Result<(), drtioaux::Error> {
+    pub fn set_rank(&self, rank: u8, timer: &mut GlobalTimer) -> Result<(), drtioaux::Error<!>> {
         if self.state != RepeaterState::Up {
             return Ok(());
         }
@@ -318,7 +318,7 @@ impl Repeater {
         Ok(())
     }
 
-    pub fn rtio_reset(&self, timer: &mut GlobalTimer) -> Result<(), drtioaux::Error> {
+    pub fn rtio_reset(&self, timer: &mut GlobalTimer) -> Result<(), drtioaux::Error<!>> {
         let repno = self.repno as usize;
         unsafe {
             (csr::DRTIOREP[repno].reset_write)(1);
@@ -361,11 +361,11 @@ impl Repeater {
     ) {
     }
 
-    pub fn sync_tsc(&self, _timer: &mut GlobalTimer) -> Result<(), drtioaux::Error> {
+    pub fn sync_tsc(&self, _timer: &mut GlobalTimer) -> Result<(), drtioaux::Error<!>> {
         Ok(())
     }
 
-    pub fn rtio_reset(&self, _timer: &mut GlobalTimer) -> Result<(), drtioaux::Error> {
+    pub fn rtio_reset(&self, _timer: &mut GlobalTimer) -> Result<(), drtioaux::Error<!>> {
         Ok(())
     }
 }

src/satman/src/routing.rs

@@ -129,7 +129,7 @@ impl Router {
         _routing_table: &drtio_routing::RoutingTable,
         _rank: u8,
         _destination: u8,
-    ) -> Result<(), drtioaux::Error> {
+    ) -> Result<(), drtioaux::Error<!>> {
         #[cfg(has_drtio_routing)]
         {
             let destination = packet.routable_destination();

src/satman/src/subkernel.rs

@@ -1,17 +1,21 @@
-use alloc::{collections::BTreeMap,
+use alloc::{
+    collections::BTreeMap,
     format,
     string::{String, ToString},
-            vec::Vec};
+    vec::Vec,
-use core::{option::NoneError, slice, str};
+};
+use core::{slice, str};
 
 use cslice::AsCSlice;
 use dma::{Error as DmaError, Manager as DmaManager};
 use io::{Cursor, Error as IoError, ProtoWrite, Write};
 use ksupport::{eh_artiq, kernel, rpc};
-use libboard_artiq::{drtio_routing::RoutingTable,
+use libboard_artiq::{
+    drtio_routing::RoutingTable,
     drtioaux,
     drtioaux_proto::{PayloadStatus, MASTER_PAYLOAD_MAX_SIZE},
-                     pl::csr};
+    pl::csr,
+};
 use libboard_zynq::{time::Milliseconds, timer::GlobalTimer};
 use libcortex_a9::sync_channel::Receiver;
 use log::warn;
@@ -51,6 +55,7 @@ enum KernelState {
     },
 }
 
+#[allow(dead_code)]
 #[derive(Debug)]
 pub enum Error {
     Load(String),
@@ -64,14 +69,8 @@ pub enum Error {
     DmaError(DmaError),
 }
 
-impl From<NoneError> for Error {
+impl<T> From<IoError<T>> for Error {
-    fn from(_: NoneError) -> Error {
+    fn from(_value: IoError<T>) -> Error {
-        Error::KernelNotFound
-    }
-}
-
-impl From<IoError> for Error {
-    fn from(_value: IoError) -> Error {
         Error::SubkernelIoError
     }
 }
@@ -88,8 +87,8 @@ impl From<()> for Error {
     }
 }
 
-impl From<drtioaux::Error> for Error {
+impl<T> From<drtioaux::Error<T>> for Error {
-    fn from(_value: drtioaux::Error) -> Error {
+    fn from(_value: drtioaux::Error<T>) -> Error {
         Error::DrtioError
     }
 }
@@ -221,7 +220,10 @@ impl MessageManager {
         }
     }
 
-    pub fn get_outgoing_slice(&mut self, data_slice: &mut [u8; MASTER_PAYLOAD_MAX_SIZE]) -> Option<SliceMeta> {
+    pub fn get_outgoing_slice(
+        &mut self,
+        data_slice: &mut [u8; MASTER_PAYLOAD_MAX_SIZE],
+    ) -> Option<SliceMeta> {
         if self.out_state != OutMessageState::MessageBeingSent {
             return None;
         }
@@ -302,7 +304,13 @@ impl<'a> Manager<'_> {
         }
     }
 
-    pub fn add(&mut self, id: u32, status: PayloadStatus, data: &[u8], data_len: usize) -> Result<(), Error> {
+    pub fn add(
+        &mut self,
+        id: u32,
+        status: PayloadStatus,
+        data: &[u8],
+        data_len: usize,
+    ) -> Result<(), Error> {
         let kernel = match self.kernels.get_mut(&id) {
             Some(kernel) => {
                 if kernel.complete || status.is_first() {
@@ -315,7 +323,7 @@ impl<'a> Manager<'_> {
                             complete: false,
                         },
                     );
-                    self.kernels.get_mut(&id)?
+                    self.kernels.get_mut(&id).ok_or(Error::KernelNotFound)?
                 } else {
                     kernel
                 }
@@ -328,7 +336,7 @@ impl<'a> Manager<'_> {
                         complete: false,
                     },
                 );
-                self.kernels.get_mut(&id)?
+                self.kernels.get_mut(&id).ok_or(Error::KernelNotFound)?
             }
         };
         kernel.library.extend(&data[0..data_len]);
@@ -372,10 +380,15 @@ impl<'a> Manager<'_> {
         if !self.running() {
             return;
         }
-        self.session.messages.handle_incoming(status, id, length, slice);
+        self.session
+            .messages
+            .handle_incoming(status, id, length, slice);
     }
 
-    pub fn message_get_slice(&mut self, slice: &mut [u8; MASTER_PAYLOAD_MAX_SIZE]) -> Option<SliceMeta> {
+    pub fn message_get_slice(
+        &mut self,
+        slice: &mut [u8; MASTER_PAYLOAD_MAX_SIZE],
+    ) -> Option<SliceMeta> {
         if !self.running() {
             return None;
         }
@@ -394,15 +407,19 @@ impl<'a> Manager<'_> {
         if self.session.id == id && self.session.kernel_state == KernelState::Loaded {
             return Ok(());
         }
-        if !self.kernels.get(&id)?.complete {
+        if !self.kernels.get(&id).ok_or(Error::KernelNotFound)?.complete {
             return Err(Error::KernelNotFound);
         }
         self.session = Session::new(id);
         self.control.restart();
 
-        self.control
+        self.control.tx.send(kernel::Message::LoadRequest(
-            .tx
+            self.kernels
-            .send(kernel::Message::LoadRequest(self.kernels.get(&id)?.library.clone()));
+                .get(&id)
+                .ok_or(Error::KernelNotFound)?
+                .library
+                .clone(),
+        ));
         let reply = self.control.rx.recv();
         match reply {
             kernel::Message::LoadCompleted => Ok(()),
@@ -414,7 +431,10 @@ impl<'a> Manager<'_> {
         }
     }
 
-    pub fn exception_get_slice(&mut self, data_slice: &mut [u8; MASTER_PAYLOAD_MAX_SIZE]) -> SliceMeta {
+    pub fn exception_get_slice(
+        &mut self,
+        data_slice: &mut [u8; MASTER_PAYLOAD_MAX_SIZE],
+    ) -> SliceMeta {
         match self.session.last_exception.as_mut() {
             Some(exception) => exception.get_slice_master(data_slice),
             None => SliceMeta {
@@ -568,7 +588,14 @@ impl<'a> Manager<'_> {
             }
         }
 
-        match self.process_kern_message(router, routing_table, rank, destination, dma_manager, timer) {
+        match self.process_kern_message(
+            router,
+            routing_table,
+            rank,
+            destination,
+            dma_manager,
+            timer,
+        ) {
             Ok(true) => {
                 self.last_finished = Some(SubkernelFinished {
                     id: self.session.id,
@@ -611,7 +638,9 @@ impl<'a> Manager<'_> {
         for (i, (status, exception_source)) in self.session.subkernels_finished.iter().enumerate() {
             if *status == id {
                 if exception_source.is_none() {
-                    self.control.tx.send(kernel::Message::SubkernelAwaitFinishReply);
+                    self.control
+                        .tx
+                        .send(kernel::Message::SubkernelAwaitFinishReply);
                     self.session.kernel_state = KernelState::Running;
                     self.session.subkernels_finished.swap_remove(i);
                 } else {
@@ -639,15 +668,26 @@ impl<'a> Manager<'_> {
         if self.session.kernel_state == KernelState::SubkernelAwaitLoad {
             self.control
                 .tx
-                .send(kernel::Message::SubkernelLoadRunReply { succeeded: succeeded });
+                .send(kernel::Message::SubkernelLoadRunReply {
+                    succeeded: succeeded,
+                });
             self.session.kernel_state = KernelState::Running;
         } else {
             warn!("received unsolicited SubkernelLoadRunReply");
         }
     }
 
-    pub fn remote_subkernel_finished(&mut self, id: u32, with_exception: bool, exception_source: u8) {
+    pub fn remote_subkernel_finished(
-        let exception_src = if with_exception { Some(exception_source) } else { None };
+        &mut self,
+        id: u32,
+        with_exception: bool,
+        exception_source: u8,
+    ) {
+        let exception_src = if with_exception {
+            Some(exception_source)
+        } else {
+            None
+        };
         self.session.subkernels_finished.push((id, exception_src));
     }
 
@@ -660,18 +700,19 @@ impl<'a> Manager<'_> {
         rank: u8,
         self_destination: u8,
     ) {
-        if let KernelState::SubkernelRetrievingException { destination } = self.session.kernel_state {
+        if let KernelState::SubkernelRetrievingException { destination } = self.session.kernel_state
+        {
             self.session
                 .external_exception
                 .as_mut()
                 .unwrap()
                 .extend_from_slice(exception_data);
             if last {
-                self.control
+                self.control.tx.send(kernel::Message::SubkernelError(
-                    .tx
+                    kernel::SubkernelStatus::Exception(
-                    .send(kernel::Message::SubkernelError(kernel::SubkernelStatus::Exception(
                         self.session.external_exception.take().unwrap(),
-                    )));
+                    ),
+                ));
                 self.session.kernel_state = KernelState::Running;
             } else {
                 /* fetch another slice */
@@ -706,7 +747,12 @@ impl<'a> Manager<'_> {
                 dma_manager.cleanup(router, rank, self_destination, routing_table);
                 return Ok(true);
             }
-            kernel::Message::KernelException(exceptions, stack_pointers, backtrace, async_errors) => {
+            kernel::Message::KernelException(
+                exceptions,
+                stack_pointers,
+                backtrace,
+                async_errors,
+            ) => {
                 error!("exception in kernel");
                 for exception in exceptions {
                     error!("{:?}", exception.unwrap());
@@ -715,12 +761,21 @@ impl<'a> Manager<'_> {
                 error!("backtrace: {:?}", backtrace);
                 let buf: Vec<u8> = Vec::new();
                 let mut writer = Cursor::new(buf);
-                match write_exception(&mut writer, exceptions, stack_pointers, backtrace, async_errors) {
+                match write_exception(
+                    &mut writer,
+                    exceptions,
+                    stack_pointers,
+                    backtrace,
+                    async_errors,
+                ) {
                     Ok(()) => (),
                     Err(_) => error!("Error writing exception data"),
                 }
                 self.kernel_stop();
-                return Err(Error::KernelException(Sliceable::new(0, writer.into_inner())));
+                return Err(Error::KernelException(Sliceable::new(
+                    0,
+                    writer.into_inner(),
+                )));
             }
             kernel::Message::CachePutRequest(key, value) => {
                 self.cache.insert(key, value);
@@ -768,11 +823,13 @@ impl<'a> Manager<'_> {
                 let max_time = timer.get_time() + Milliseconds(10000);
                 self.session.kernel_state = match self.session.kernel_state {
                     // if we are still waiting for the traces to be uploaded, extend the state by timeout
-                    KernelState::DmaPendingPlayback { id, timestamp } => KernelState::DmaPendingAwait {
+                    KernelState::DmaPendingPlayback { id, timestamp } => {
+                        KernelState::DmaPendingAwait {
                             id: id,
                             timestamp: timestamp,
                             max_time: max_time,
-                    },
+                        }
+                    }
                     _ => KernelState::DmaAwait { max_time: max_time },
                 };
             }
@@ -843,7 +900,10 @@ impl<'a> Manager<'_> {
                 ));
             }
             _ => {
-                unexpected!("unexpected message from core1 while kernel was running: {:?}", reply);
+                unexpected!(
+                    "unexpected message from core1 while kernel was running: {:?}",
+                    reply
+                );
             }
         }
         Ok(false)
@@ -861,9 +921,9 @@ impl<'a> Manager<'_> {
             KernelState::MsgAwait { max_time, id, tags } => {
                 if let Some(max_time) = *max_time {
                     if timer.get_time() > max_time {
-                        self.control
+                        self.control.tx.send(kernel::Message::SubkernelError(
-                            .tx
+                            kernel::SubkernelStatus::Timeout,
-                            .send(kernel::Message::SubkernelError(kernel::SubkernelStatus::Timeout));
+                        ));
                         self.session.kernel_state = KernelState::Running;
                         return Ok(());
                     }
@@ -871,7 +931,9 @@ impl<'a> Manager<'_> {
                 if let Some(message) = self.session.messages.get_incoming(*id) {
                     self.control
                         .tx
-                        .send(kernel::Message::SubkernelMsgRecvReply { count: message.count });
+                        .send(kernel::Message::SubkernelMsgRecvReply {
+                            count: message.count,
+                        });
                     let tags = tags.clone();
                     self.session.kernel_state = KernelState::Running;
                     self.pass_message_to_kernel(&message, tags, timer)
@@ -893,9 +955,9 @@ impl<'a> Manager<'_> {
             KernelState::SubkernelAwaitFinish { max_time, id } => {
                 if let Some(max_time) = *max_time {
                     if timer.get_time() > max_time {
-                        self.control
+                        self.control.tx.send(kernel::Message::SubkernelError(
-                            .tx
+                            kernel::SubkernelStatus::Timeout,
-                            .send(kernel::Message::SubkernelError(kernel::SubkernelStatus::Timeout));
+                        ));
                         self.session.kernel_state = KernelState::Running;
                         return Ok(());
                     }
@@ -921,7 +983,12 @@ impl<'a> Manager<'_> {
         }
     }
 
-    fn pass_message_to_kernel(&mut self, message: &Message, tags: Vec<u8>, timer: &GlobalTimer) -> Result<(), Error> {
+    fn pass_message_to_kernel(
+        &mut self,
+        message: &Message,
+        tags: Vec<u8>,
+        timer: &GlobalTimer,
+    ) -> Result<(), Error> {
         let mut reader = Cursor::new(&message.data);
         let mut current_tags: &[u8] = &tags;
         let mut i = message.count;
@@ -932,29 +999,50 @@ impl<'a> Manager<'_> {
             };
             let mut exception: Option<Sliceable> = None;
             let mut unexpected: Option<String> = None;
-            let remaining_tags = rpc::recv_return(&mut reader, current_tags, slot, &mut |size| {
+            let remaining_tags =
+                rpc::recv_return(&mut reader, current_tags, slot, &mut |size| -> Result<
+                    _,
+                    Error,
+                > {
                     if size == 0 {
-                    0 as *mut ()
+                        Ok(0 as *mut ())
                     } else {
-                    self.control.tx.send(kernel::Message::RpcRecvReply(Ok(size)));
+                        self.control
+                            .tx
+                            .send(kernel::Message::RpcRecvReply(Ok(size)));
                         match recv_w_timeout(&mut self.control.rx, timer, 100) {
-                        Ok(kernel::Message::RpcRecvRequest(slot)) => slot,
+                            Ok(kernel::Message::RpcRecvRequest(slot)) => Ok(slot),
-                        Ok(kernel::Message::KernelException(exceptions, stack_pointers, backtrace, async_errors)) => {
+                            Ok(kernel::Message::KernelException(
+                                exceptions,
+                                stack_pointers,
+                                backtrace,
+                                async_errors,
+                            )) => {
                                 let buf: Vec<u8> = Vec::new();
                                 let mut writer = Cursor::new(buf);
-                            match write_exception(&mut writer, exceptions, stack_pointers, backtrace, async_errors) {
+                                match write_exception(
+                                    &mut writer,
+                                    exceptions,
+                                    stack_pointers,
+                                    backtrace,
+                                    async_errors,
+                                ) {
                                     Ok(()) => {
                                         exception = Some(Sliceable::new(0, writer.into_inner()));
                                     }
                                     Err(_) => {
-                                    unexpected = Some("Error writing exception data".to_string());
+                                        unexpected =
+                                            Some("Error writing exception data".to_string());
                                     }
                                 };
-                            0 as *mut ()
+                                Ok(0 as *mut ())
                             }
                             other => {
-                            unexpected = Some(format!("expected nested value slot from kernel CPU, not {:?}", other));
+                                unexpected = Some(format!(
-                            0 as *mut ()
+                                    "expected nested value slot from kernel CPU, not {:?}",
+                                    other
+                                ));
+                                Ok(0 as *mut ())
                             }
                         }
                     }
@@ -1000,8 +1088,9 @@ where
             writer.write_u32(u32::MAX)?;
             writer.write_u32(exception.message.as_ptr() as u32)?;
         } else {
-            let msg =
+            let msg = str::from_utf8(unsafe {
-                str::from_utf8(unsafe { slice::from_raw_parts(exception.message.as_ptr(), exception.message.len()) })
+                slice::from_raw_parts(exception.message.as_ptr(), exception.message.len())
+            })
             .unwrap()
             .replace(
                 "{rtio_channel_info:0}",