about to add argument support

Signed-off-by: Sean Cross <sean@xobs.io>

crates/riscv-cpu/src/mmu.rs

@@ -1,4 +1,5 @@
 use std::{
+    collections::HashMap,
     sync::mpsc::Receiver,
     sync::{Arc, Mutex},
 };
@@ -51,11 +52,12 @@ pub struct Mmu {
     privilege_mode: PrivilegeMode,
     memory: Arc<Mutex<dyn Memory + Send + Sync>>,
 
-    // /// The size of main memory (if initialized)
-    // memory_length: Option<NonZeroU64>,
     /// Address translation can be affected `mstatus` (MPRV, MPP in machine mode)
     /// then `Mmu` has copy of it.
     mstatus: u64,
+
+    /// A cache of instructions. We assume that instruction memory does not change.
+    instruction_cache: Arc<Mutex<HashMap<u64, u32>>>,
 }
 
 #[derive(Debug)]
@@ -96,6 +98,7 @@ impl Mmu {
             privilege_mode: PrivilegeMode::Machine,
             memory,
             mstatus: 0,
+            instruction_cache: Arc::new(Mutex::new(HashMap::new())),
         }
     }
 
@@ -170,13 +173,23 @@ impl Mmu {
     /// # Arguments
     /// * `v_address` Virtual address
     pub fn fetch_word(&self, v_address: u64) -> Result<u32, Trap> {
+        // if let Some(data) = self.instruction_cache.lock().unwrap().get(&v_address) {
+        //     return Ok(*data);
+        // }
         let width = 4;
         if (v_address & 0xfff) <= (0x1000 - width) {
             // Fast path. All bytes fetched are in the same page so
             // translating an address only once.
             let effective_address = self.trim_to_xlen(v_address);
             self.translate_address(effective_address, &MemoryAccessType::Execute)
-                .map(|p_address| self.load_word_raw(p_address))
+                .map(|p_address| {
+                    let data = self.load_word_raw(p_address);
+                    self.instruction_cache
+                        .lock()
+                        .unwrap()
+                        .insert(v_address, data);
+                    data
+                })
                 .map_err(|()| Trap {
                     trap_type: TrapType::InstructionPageFault,
                     value: effective_address,
@@ -189,6 +202,10 @@ impl Mmu {
                     Err(e) => return Err(e),
                 };
             }
+            self.instruction_cache
+                .lock()
+                .unwrap()
+                .insert(v_address, data);
             Ok(data)
         }
     }

src/xous.rs

@@ -147,7 +147,6 @@ struct Memory {
     free_pages: BTreeSet<usize>,
     heap_start: u32,
     heap_size: u32,
-    // allocation_start: u32,
     allocation_previous: u32,
     l1_pt: u32,
     satp: u32,
@@ -664,33 +663,13 @@ impl riscv_cpu::cpu::Memory for Memory {
                 argument_2,
                 argument_3,
                 argument_4,
-            ) => {
+            ) => syscalls::create_thread(
-                let (tx, rx) = std::sync::mpsc::channel();
+                self,
-                self.memory_cmd
+                entry_point,
-                    .send(MemoryCommand::CreateThread(
+                stack_pointer,
-                        entry_point as _,
+                stack_length,
-                        stack_pointer as _,
+                [argument_1, argument_2, argument_3, argument_4],
-                        stack_length as _,
+            ),
-                        argument_1 as _,
-                        argument_2 as _,
-                        argument_3 as _,
-                        argument_4 as _,
-                        tx,
-                    ))
-                    .unwrap();
-                let thread_id = rx.recv().unwrap();
-                [
-                    SyscallResultNumber::ThreadId as i64,
-                    thread_id,
-                    0,
-                    0,
-                    0,
-                    0,
-                    0,
-                    0,
-                ]
-                .into()
-            }
             Syscall::UnmapMemory(address, size) => {
                 // println!("UnmapMemory({:08x}, {})", address, size);
                 for offset in (address..address + size).step_by(4096) {

src/xous/services.rs

@@ -1,6 +1,9 @@
 use std::sync::mpsc::Receiver;
 pub mod log;
+pub mod name;
+pub mod panic_to_screen;
 pub mod ticktimer;
+use super::Memory;
 
 pub type ResponseData = ([i64; 8], Option<(Vec<u8>, u64)>);
 
@@ -19,48 +22,97 @@ pub enum LendResult {
 }
 
 pub trait Service {
-    fn scalar(&mut self, sender: u32, opcode: u32, _args: [u32; 4]) {
+    fn scalar(&mut self, _memory: &mut Memory, sender: u32, opcode: u32, args: [u32; 4]) {
-        panic!("Unknown scalar to service {}: {}", sender, opcode);
-    }
-    fn blocking_scalar(&mut self, sender: u32, opcode: u32, _args: [u32; 4]) -> ScalarResult {
-        panic!("Unknown scalar to service {}: {}", sender, opcode);
-    }
-    fn lend(&mut self, sender: u32, opcode: u32, _buf: &[u8], extra: [u32; 2]) -> LendResult {
         panic!(
-            "Unknown lend to service {}: {} ({:?})",
+            "Unknown scalar to service {}: {} ({:?})",
-            sender, opcode, extra
+            sender, opcode, args
         );
     }
 
-    /// Mutable lend messages may block
+    fn blocking_scalar(
-    fn lend_mut(
         &mut self,
+        _memory: &mut Memory,
         sender: u32,
         opcode: u32,
-        _buf: &mut [u8],
+        args: [u32; 4],
+    ) -> ScalarResult {
+        panic!(
+            "Unknown scalar to service {}: {} ({:?})",
+            sender, opcode, args
+        );
+    }
+
+    fn lend(
+        &mut self,
+        _memory: &mut Memory,
+        sender: u32,
+        opcode: u32,
+        buf: &[u8],
         extra: [u32; 2],
     ) -> LendResult {
         panic!(
-            "Unknown lend_mut to service {}: {} ({:?})",
+            "Unknown lend {} bytes to service {}: {} ({:?})",
-            sender, opcode, extra
+            buf.len(),
+            sender,
+            opcode,
+            extra
         );
     }
 
-    /// Send-type messages return immediately, and memory is detached from the host process.
+    fn lend_mut(
-    fn send(&mut self, sender: u32, opcode: u32, _buf: &[u8], extra: [u32; 2]) {
+        &mut self,
+        _memory: &mut Memory,
+        sender: u32,
+        opcode: u32,
+        buf: &mut [u8],
+        extra: [u32; 2],
+    ) -> LendResult {
         panic!(
-            "Unknown send to service {}: {} ({:?})",
+            "Unknown lend_mut {} bytes to service {}: {} ({:?})",
-            sender, opcode, extra
+            buf.len(),
+            sender,
+            opcode,
+            extra
+        );
+    }
+
+    fn send(
+        &mut self,
+        _memory: &mut Memory,
+        sender: u32,
+        opcode: u32,
+        buf: &[u8],
+        extra: [u32; 2],
+    ) {
+        panic!(
+            "Unknown send {} bytes to service {}: {} ({:?})",
+            buf.len(),
+            sender,
+            opcode,
+            extra
         );
     }
 }
 
 pub fn get_service(name: &[u32; 4]) -> Option<Box<dyn Service + Sync + Send>> {
+    let mut output_bfr = [0u8; core::mem::size_of::<u32>() * 4 /*args.len()*/];
+    // Combine the four arguments to form a single
+    // contiguous buffer. Note: The buffer size will change
+    // depending on the platfor's `usize` length.
+    for (src, dest) in name.iter().zip(output_bfr.chunks_mut(4)) {
+        dest.copy_from_slice(src.to_le_bytes().as_ref());
+    }
+    println!(
+        "Connecting to service: {}",
+        std::str::from_utf8(&output_bfr).unwrap_or("<invalid name>")
+    );
+
     match name {
         [0x6b636974, 0x656d6974, 0x65732d72, 0x72657672] => {
             Some(Box::new(ticktimer::Ticktimer::new()))
         }
         [0x73756f78, 0x676f6c2d, 0x7265732d, 0x20726576] => Some(Box::new(log::Log::new())),
-        _ => None,
+        [0x73756f78, 0x6d616e2d, 0x65732d65, 0x72657672] => Some(Box::new(name::Name::new())),
+        _ => panic!("Unhandled service request: {:x?}", name),
     }
 }

src/xous/services/log.rs

@@ -1,4 +1,5 @@
 use super::{LendResult, ScalarResult, Service};
+use crate::xous::Memory;
 use std::io::Write;
 
 enum LogLendOpcode {
@@ -9,11 +10,54 @@ enum LogLendOpcode {
     StandardError = 2,
 }
 
+#[allow(dead_code)]
+enum LogSendOpcode {
+    /// A panic occurred, and a panic log is forthcoming
+    PanicStarted = 1000,
+
+    /// Log messages of varying size
+    PanicMessage0 = 1100,
+    PanicMessage1 = 1101,
+    PanicMessage2 = 1102,
+    PanicMessage3 = 1103,
+    PanicMessage4 = 1104,
+    PanicMessage5 = 1105,
+    PanicMessage6 = 1106,
+    PanicMessage7 = 1107,
+    PanicMessage8 = 1108,
+    PanicMessage9 = 1109,
+    PanicMessage10 = 1110,
+    PanicMessage11 = 1111,
+    PanicMessage12 = 1112,
+    PanicMessage13 = 1113,
+    PanicMessage14 = 1114,
+    PanicMessage15 = 1115,
+    PanicMessage16 = 1116,
+    PanicMessage17 = 1117,
+    PanicMessage18 = 1118,
+    PanicMessage19 = 1119,
+    PanicMessage20 = 1120,
+    PanicMessage21 = 1121,
+    PanicMessage22 = 1122,
+    PanicMessage23 = 1123,
+    PanicMessage24 = 1124,
+    PanicMessage25 = 1125,
+    PanicMessage26 = 1126,
+    PanicMessage27 = 1127,
+    PanicMessage28 = 1128,
+    PanicMessage29 = 1129,
+    PanicMessage30 = 1130,
+    PanicMessage31 = 1131,
+    PanicMessage32 = 1132,
+
+    /// End of a panic
+    PanicFinished = 1200,
+}
+
 pub struct Log {}
 
 impl Log {
     pub fn new() -> Self {
-        // println!("Constructing a log server");
         Log {}
     }
 }
@@ -25,16 +69,64 @@ impl Default for Log {
 }
 
 impl Service for Log {
-    fn scalar(&mut self, sender: u32, opcode: u32, args: [u32; 4]) {
+    fn scalar(&mut self, _memory: &mut Memory, sender: u32, opcode: u32, args: [u32; 4]) {
-        println!("Log scalar {}: {} {:x?}", sender, opcode, args);
+        let message_bytes = if opcode >= LogSendOpcode::PanicMessage0 as u32
+            && opcode <= LogSendOpcode::PanicMessage32 as u32
+        {
+            Some(opcode - LogSendOpcode::PanicMessage0 as u32)
+        } else {
+            None
+        };
+
+        if LogSendOpcode::PanicStarted as u32 == opcode {
+            println!("Panic started");
+        } else if LogSendOpcode::PanicFinished as u32 == opcode {
+            println!();
+            println!("Panic finished");
+        } else if let Some(message_bytes) = message_bytes {
+            let mut output_bfr = [0u8; core::mem::size_of::<u32>() * 4 /*args.len()*/];
+            // let mut output_iter = output_bfr.iter_mut();
+
+            // Combine the four arguments to form a single
+            // contiguous buffer. Note: The buffer size will change
+            // depending on the platfor's `usize` length.
+            for (src, dest) in args.iter().zip(output_bfr.chunks_mut(4)) {
+                dest.copy_from_slice(src.to_le_bytes().as_ref());
+                // for src in word.to_le_bytes().iter() {
+                //     *(output_iter.next().unwrap()) = *src;
+                // }
+            }
+            print!(
+                "{}",
+                std::str::from_utf8(&output_bfr[0..message_bytes as usize]).unwrap_or("<invalid>")
+            );
+        } else {
+            println!("Log scalar {}: {} {:x?}", sender, opcode, args);
+        }
     }
 
-    fn blocking_scalar(&mut self, sender: u32, opcode: u32, args: [u32; 4]) -> ScalarResult {
+    fn blocking_scalar(
-        println!("Log blocking_scalar {}: {} {:x?}", sender, opcode, args);
+        &mut self,
+        _memory: &mut Memory,
+        sender: u32,
+        opcode: u32,
+        args: [u32; 4],
+    ) -> ScalarResult {
+        println!(
+            "Unhandled log blocking_scalar {}: {} {:x?}",
+            sender, opcode, args
+        );
         ScalarResult::Scalar1(0)
     }
 
-    fn lend(&mut self, sender: u32, opcode: u32, buf: &[u8], extra: [u32; 2]) -> LendResult {
+    fn lend(
+        &mut self,
+        _memory: &mut Memory,
+        sender: u32,
+        opcode: u32,
+        buf: &[u8],
+        extra: [u32; 2],
+    ) -> LendResult {
         if opcode == LogLendOpcode::StandardOutput as u32 {
             let print_buffer = &buf[0..extra[1] as usize];
             // println!("Log stdout:");
@@ -46,23 +138,31 @@ impl Service for Log {
             std::io::stderr().write_all(print_buffer).unwrap();
             std::io::stderr().flush().unwrap();
         } else {
-            panic!("Log lend {}: {} {:x?}", sender, opcode, buf);
+            panic!("Unhandled log lend {}: {} {:x?}", sender, opcode, buf);
         }
         LendResult::MemoryReturned([0, 0])
     }
 
     fn lend_mut(
         &mut self,
+        _memory: &mut Memory,
         sender: u32,
         opcode: u32,
         _buf: &mut [u8],
         extra: [u32; 2],
     ) -> LendResult {
-        println!("Log lend_mut {}: {} {:x?}", sender, opcode, extra);
+        println!("Unhandled log lend_mut {}: {} {:x?}", sender, opcode, extra);
         LendResult::MemoryReturned([0, 0])
     }
 
-    fn send(&mut self, sender: u32, opcode: u32, _buf: &[u8], extra: [u32; 2]) {
+    fn send(
-        println!("Log send {}: {} {:x?}", sender, opcode, extra);
+        &mut self,
+        _memory: &mut Memory,
+        sender: u32,
+        opcode: u32,
+        _buf: &[u8],
+        extra: [u32; 2],
+    ) {
+        println!("Unhandled log send {}: {} {:x?}", sender, opcode, extra);
     }
 }

src/xous/services/name.rs

@@ -0,0 +1,179 @@
+use crate::xous::Memory;
+
+use super::{LendResult, ScalarResult, Service};
+
+#[allow(dead_code)]
+enum NameLendOpcode {
+    /// Create a new server with the given name and return its SID.
+    Register = 0,
+
+    /// Create a connection to the target server.
+    Lookup = 1,
+
+    /// Create an authenticated connection to the target server.
+    AuthenticatedLookup = 2,
+
+    /// unregister a server, given its cryptographically unique SID.
+    Unregister = 3,
+
+    /// disconnect, given a server name and a cryptographically unique, one-time use token
+    Disconnect = 4,
+
+    /// indicates if all inherently trusted slots have been occupied. Should not run untrusted code until this is the case.
+    TrustedInitDone = 5,
+
+    /// Connect to a Server, blocking if the Server does not exist. When the Server is started,
+    /// return with either the CID or an AuthenticationRequest
+    ///
+    /// # Message Types
+    ///
+    ///     * MutableLend
+    ///
+    /// # Arguments
+    ///
+    /// The memory being pointed to should be a &str, and the length of the string should
+    /// be specified in the `valid` field.
+    ///
+    /// # Return Values
+    ///
+    /// Memory is overwritten to contain a return value.  This return value can be defined
+    /// as the following enum:
+    ///
+    /// ```rust
+    /// #[repr(C)]
+    /// #[non_exhaustive]
+    /// enum ConnectResult {
+    ///     Success(xous::CID /* connection ID */, [u32; 4] /* Disconnection token */),
+    ///     Error(u32 /* error code */),
+    ///     Unhandled, /* Catchall for future Results */
+    /// }
+    /// ```
+    BlockingConnect = 6,
+
+    /// Connect to a Server, returning the connection ID or an authentication request if
+    /// it exists, and returning ServerNotFound if it does not exist.
+    ///
+    /// # Message Types
+    ///
+    ///     * MutableLend
+    ///
+    /// # Arguments
+    ///
+    /// The memory being pointed to should be a &str, and the length of the string should
+    /// be specified in the `valid` field.
+    ///
+    /// # Return Values
+    ///
+    /// Memory is overwritten to contain a return value.  This return value can be defined
+    /// as the following enum:
+    ///
+    /// ```rust
+    /// #[repr(C)]
+    /// #[non_exhaustive]
+    /// enum ConnectResult {
+    ///     Success(xous::CID /* connection ID */, [u32; 4] /* Disconnection token */),
+    ///     Error(u32 /* error code */),
+    ///     Unhandled, /* Catchall for future Results */
+    /// }
+    /// ```
+    TryConnect = 7,
+}
+
+pub struct Name {}
+
+impl Name {
+    pub fn new() -> Self {
+        Name {}
+    }
+}
+
+impl Default for Name {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl Service for Name {
+    fn scalar(&mut self, _memory: &mut Memory, sender: u32, opcode: u32, args: [u32; 4]) {
+        panic!("Unhandled name scalar {}: {} {:x?}", sender, opcode, args);
+    }
+
+    fn blocking_scalar(
+        &mut self,
+        _memory: &mut Memory,
+        sender: u32,
+        opcode: u32,
+        args: [u32; 4],
+    ) -> ScalarResult {
+        panic!(
+            "Unhandled name blocking_scalar {}: {} {:x?}",
+            sender, opcode, args
+        );
+        // ScalarResult::Scalar1(0)
+    }
+
+    fn lend(
+        &mut self,
+        _memory: &mut Memory,
+        sender: u32,
+        opcode: u32,
+        buf: &[u8],
+        extra: [u32; 2],
+    ) -> LendResult {
+        panic!(
+            "Unhandled name lend {}: {} {:x?} {:x?}",
+            sender, opcode, buf, extra
+        );
+        // LendResult::MemoryReturned([0, 0])
+    }
+
+    fn lend_mut(
+        &mut self,
+        memory: &mut Memory,
+        sender: u32,
+        opcode: u32,
+        buf: &mut [u8],
+        extra: [u32; 2],
+    ) -> LendResult {
+        if opcode == NameLendOpcode::Register as u32 {
+            panic!("Register opcode unimplemented");
+        } else if opcode == NameLendOpcode::TryConnect as u32
+            || opcode == NameLendOpcode::BlockingConnect as u32
+        {
+            let buf_len = buf.len().min(extra[1] as usize);
+            let name = std::str::from_utf8(&buf[0..buf_len]).unwrap_or("<invalid>");
+            println!("Registering name {}", name);
+
+            let service = Box::new(if name == "panic-to-screen!" {
+                println!("Panic-to-screen registered");
+                super::panic_to_screen::PanicToScreen::new()
+            } else {
+                panic!("Unrecognized service name {}", name);
+            });
+
+            let connection_id = memory.connections.len() as u32 + 1;
+            memory.connections.insert(connection_id, service);
+
+            buf[0..4].copy_from_slice(&0u32.to_le_bytes());
+            buf[4..8].copy_from_slice(&connection_id.to_le_bytes());
+            LendResult::MemoryReturned([0, 0])
+        } else {
+            panic!(
+                "Unhandled name lend_mut {}: {} {:x?}",
+                sender, opcode, extra
+            );
+        }
+        //
+    }
+
+    fn send(
+        &mut self,
+        _memory: &mut Memory,
+        sender: u32,
+        opcode: u32,
+        _buf: &[u8],
+        extra: [u32; 2],
+    ) {
+        panic!("Unhandled name send {}: {} {:x?}", sender, opcode, extra);
+    }
+}

src/xous/services/panic_to_screen.rs

@@ -0,0 +1,39 @@
+use super::{LendResult, Service};
+use crate::xous::Memory;
+
+enum PanicToScreenLendMutOpcode {
+    AppendPanicText = 0,
+}
+
+pub struct PanicToScreen {}
+
+impl PanicToScreen {
+    pub fn new() -> Self {
+        PanicToScreen {}
+    }
+}
+
+impl Default for PanicToScreen {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl Service for PanicToScreen {
+    fn lend_mut(
+        &mut self,
+        _memory: &mut Memory,
+        _sender: u32,
+        opcode: u32,
+        buf: &mut [u8],
+        extra: [u32; 2],
+    ) -> LendResult {
+        if opcode != PanicToScreenLendMutOpcode::AppendPanicText as _ {
+            panic!("Unhandled panic-to-screen opcode {}", opcode);
+        }
+
+        let panic_str = std::str::from_utf8(&buf[0..extra[1] as usize]).unwrap_or("<invalid>");
+        println!("Panic to screen: {}", panic_str);
+        LendResult::MemoryReturned([0, 0])
+    }
+}

src/xous/services/ticktimer.rs

@@ -5,6 +5,7 @@ use std::{
 };
 
 use super::LendResult;
+use crate::xous::Memory;
 
 pub struct Ticktimer {
     start: std::time::SystemTime,
@@ -35,16 +36,24 @@ impl Default for Ticktimer {
 }
 
 impl super::Service for Ticktimer {
-    fn scalar(&mut self, _sender: u32, opcode: u32, args: [u32; 4]) {
+    fn scalar(&mut self, _memory: &mut Memory, _sender: u32, opcode: u32, args: [u32; 4]) {
         if opcode == ScalarOpcode::FreeCondition as u32 {
             let condition_index = args[0] as usize;
             if let Some(condvar) = self.condvars.remove(&condition_index) {
                 assert!(condvar.1.load(std::sync::atomic::Ordering::Relaxed) == 0);
             }
+        } else {
+            println!("Unhandled scalar: {}", opcode);
         }
     }
 
-    fn blocking_scalar(&mut self, sender: u32, opcode: u32, args: [u32; 4]) -> super::ScalarResult {
+    fn blocking_scalar(
+        &mut self,
+        _memory: &mut Memory,
+        sender: u32,
+        opcode: u32,
+        args: [u32; 4],
+    ) -> super::ScalarResult {
         if opcode == ScalarOpcode::ElapsedMs as u32 {
             let elapsed_ms = std::time::SystemTime::now()
                 .duration_since(self.start)
@@ -118,19 +127,27 @@ impl super::Service for Ticktimer {
             super::ScalarResult::Scalar1(notify_count as u32)
         } else {
             panic!(
-                "Ticktimer blocking_scalar {}: {} {:x?}",
+                "Ticktimer unhandled blocking_scalar {}: {} {:x?}",
                 sender, opcode, args
             );
         }
     }
 
-    fn lend(&mut self, sender: u32, opcode: u32, _buf: &[u8], extra: [u32; 2]) -> LendResult {
+    fn lend(
+        &mut self,
+        _memory: &mut Memory,
+        sender: u32,
+        opcode: u32,
+        _buf: &[u8],
+        extra: [u32; 2],
+    ) -> LendResult {
         println!("Ticktimer lend {}: {} {:x?}", sender, opcode, extra);
         LendResult::MemoryReturned([0, 0])
     }
 
     fn lend_mut(
         &mut self,
+        _memory: &mut Memory,
         sender: u32,
         opcode: u32,
         _buf: &mut [u8],
@@ -140,7 +157,14 @@ impl super::Service for Ticktimer {
         LendResult::MemoryReturned([0, 0])
     }
 
-    fn send(&mut self, sender: u32, opcode: u32, _buf: &[u8], extra: [u32; 2]) {
+    fn send(
+        &mut self,
+        _memory: &mut Memory,
+        sender: u32,
+        opcode: u32,
+        _buf: &[u8],
+        extra: [u32; 2],
+    ) {
         println!("Ticktimer send {}: {} {:x?}", sender, opcode, extra);
     }
 }

src/xous/syscalls.rs

@@ -1,3 +1,6 @@
+use std::sync::mpsc::channel;
+
+use super::super::xous::services::get_service;
 use super::definitions::{SyscallErrorNumber, SyscallResultNumber};
 use super::services;
 use super::Memory;
@@ -58,7 +61,7 @@ pub fn connect(memory: &mut Memory, id: [u32; 4]) -> SyscallResult {
     //     "Connect([0x{:08x}, 0x{:08x}, 0x{:08x}, 0x{:08x}])",
     //     id[0], id[1], id[2], id[3]
     // );
-    if let Some(service) = super::super::xous::services::get_service(&id) {
+    if let Some(service) = get_service(&id) {
         let connection_id = memory.connections.len() as u32 + 1;
         memory.connections.insert(connection_id, service);
         [
@@ -91,7 +94,6 @@ pub fn try_connect(memory: &mut Memory, id: [u32; 4]) -> SyscallResult {
     connect(memory, id)
 }
 
-
 pub fn send_message(
     memory: &mut Memory,
     connection_id: u32,
@@ -116,11 +118,13 @@ pub fn send_message(
     } else {
         None
     };
-    let Some(service) = memory.connections.get_mut(&connection_id) else {
+    // Pull the service out of the connections table so that we can send
+    // a mutable copy of the memory object to the service.
+    let Some(mut service) = memory.connections.remove(&connection_id) else {
         println!("Unhandled connection ID {}", connection_id);
         return [
             SyscallResultNumber::Error as i64,
-            9, /* ServerNotFound */
+            SyscallErrorNumber::ServerNotFound as i64,
             0,
             0,
             0,
@@ -130,12 +134,12 @@ pub fn send_message(
         ]
         .into();
     };
-    match kind {
+    let response = match kind {
         1..=3 => {
             let mut memory_region = memory_region.unwrap();
             let extra = [args[2], args[3]];
             match kind {
-                1 => match service.lend_mut(0, opcode, &mut memory_region, extra) {
+                1 => match service.lend_mut(memory, 0, opcode, &mut memory_region, extra) {
                     services::LendResult::WaitForResponse(msg) => msg.into(),
                     services::LendResult::MemoryReturned(result) => {
                         for (offset, value) in memory_region.into_iter().enumerate() {
@@ -154,7 +158,7 @@ pub fn send_message(
                         .into()
                     }
                 },
-                2 => match service.lend(0, opcode, &memory_region, extra) {
+                2 => match service.lend(memory, 0, opcode, &memory_region, extra) {
                     services::LendResult::WaitForResponse(msg) => msg.into(),
                     services::LendResult::MemoryReturned(result) => [
                         SyscallResultNumber::MemoryReturned as i64,
@@ -169,17 +173,17 @@ pub fn send_message(
                     .into(),
                 },
                 3 => {
-                    service.send(0, opcode, &memory_region, extra);
+                    service.send(memory, 0, opcode, &memory_region, extra);
                     [SyscallResultNumber::Ok as i64, 0, 0, 0, 0, 0, 0, 0].into()
                 }
                 _ => unreachable!(),
             }
         }
         4 => {
-            service.scalar(0, opcode, args);
+            service.scalar(memory, 0, opcode, args);
             [SyscallResultNumber::Ok as i64, 0, 0, 0, 0, 0, 0, 0].into()
         }
-        5 => match service.blocking_scalar(0, opcode, args) {
+        5 => match service.blocking_scalar(memory, 0, opcode, args) {
             services::ScalarResult::Scalar1(result) => [
                 SyscallResultNumber::Scalar1 as i64,
                 result as i64,
@@ -216,20 +220,22 @@ pub fn send_message(
             services::ScalarResult::WaitForResponse(msg) => msg.into(),
         },
         _ => {
-            println!("Unknown message kind {}", kind);
+            panic!("Unknown message kind {}", kind);
-            [
+            // [
-                SyscallResultNumber::Error as i64,
+            //     SyscallResultNumber::Error as i64,
-                9, /* ServerNotFound */
+            //     9, /* ServerNotFound */
-                0,
+            //     0,
-                0,
+            //     0,
-                0,
+            //     0,
-                0,
+            //     0,
-                0,
+            //     0,
-                0,
+            //     0,
-            ]
+            // ]
-            .into()
+            // .into()
         }
-    }
+    };
+    memory.connections.insert(connection_id, service);
+    response
 }
 
 pub fn try_send_message(
@@ -294,3 +300,38 @@ pub fn increase_heap(memory: &mut Memory, delta: i64, _flags: i64) -> SyscallRes
         .into()
     }
 }
+
+pub fn create_thread(
+    memory: &mut Memory,
+    entry_point: i64,
+    stack_pointer: i64,
+    stack_length: i64,
+    arguments: [i64; 4],
+) -> SyscallResult {
+    let (tx, rx) = channel();
+    memory
+        .memory_cmd
+        .send(super::MemoryCommand::CreateThread(
+            entry_point as _,
+            stack_pointer as _,
+            stack_length as _,
+            arguments[0] as _,
+            arguments[1] as _,
+            arguments[2] as _,
+            arguments[3] as _,
+            tx,
+        ))
+        .unwrap();
+    let thread_id = rx.recv().unwrap();
+    [
+        SyscallResultNumber::ThreadId as i64,
+        thread_id,
+        0,
+        0,
+        0,
+        0,
+        0,
+        0,
+    ]
+    .into()
+}