Rust: implement basic communication with kernel CPU.

artiq/runtime.rs/Cargo.toml

@@ -8,7 +8,7 @@ build = "build.rs"
 walkdir = "0.1"
 
 [lib]
-name = "artiq_rust"
+name = "runtime"
 crate-type = ["staticlib"]
 path = "src/lib.rs"
 

artiq/runtime.rs/liblwip-sys/lib.rs

@@ -122,25 +122,25 @@ extern {
     pub fn tcp_bind(pcb: *mut tcp_pcb, ipaddr: *mut ip_addr, port: u16) -> err;
     pub fn tcp_listen_with_backlog(pcb: *mut tcp_pcb, backlog: u8) -> *mut tcp_pcb;
     pub fn tcp_accept(pcb: *mut tcp_pcb,
-                      accept: extern fn(arg: *mut c_void, newpcb: *mut tcp_pcb,
-                                        err: err) -> err);
+                      accept: Option<extern fn(arg: *mut c_void, newpcb: *mut tcp_pcb,
+                                               err: err) -> err>);
     pub fn tcp_connect(pcb: *mut tcp_pcb, ipaddr: *mut ip_addr, port: u16,
                        connected: extern fn(arg: *mut c_void, tcb: *mut tcp_pcb, err: err)) -> err;
     pub fn tcp_write(pcb: *mut tcp_pcb, dataptr: *const c_void, len: u16, apiflags: u8) -> err;
     pub fn tcp_sent(pcb: *mut tcp_pcb,
-                    sent: extern fn(arg: *mut c_void, tcb: *mut tcp_pcb, len: u16) -> err);
+                    sent: Option<extern fn(arg: *mut c_void, tcb: *mut tcp_pcb, len: u16) -> err>);
     pub fn tcp_recv(pcb: *mut tcp_pcb,
-                    recv: extern fn(arg: *mut c_void, tcb: *mut tcp_pcb, p: *mut pbuf,
-                                    err: err) -> err);
+                    recv: Option<extern fn(arg: *mut c_void, tcb: *mut tcp_pcb, p: *mut pbuf,
+                                           err: err) -> err>);
     pub fn tcp_recved(pcb: *mut tcp_pcb, len: u16);
     pub fn tcp_poll(pcb: *mut tcp_pcb,
-                    poll: extern fn(arg: *mut c_void, tcb: *mut tcp_pcb),
+                    poll: Option<extern fn(arg: *mut c_void, tcb: *mut tcp_pcb)>,
                     interval: u8);
     pub fn tcp_shutdown(pcb: *mut tcp_pcb, shut_rx: c_int, shut_tx: c_int) -> err;
     pub fn tcp_close(pcb: *mut tcp_pcb) -> err;
     pub fn tcp_abort(pcb: *mut tcp_pcb);
     pub fn tcp_err(pcb: *mut tcp_pcb,
-                   err: extern fn(arg: *mut c_void, err: err));
+                   err: Option<extern fn(arg: *mut c_void, err: err)>);
 
     // nonstandard
     pub fn tcp_sndbuf_(pcb: *mut tcp_pcb) -> u16;
@@ -154,7 +154,7 @@ extern {
     pub fn udp_send(pcb: *mut udp_pcb, p: *mut pbuf) -> err;
     pub fn udp_sendto(pcb: *mut udp_pcb, p: *mut pbuf, ipaddr: *mut ip_addr, port: u16) -> err;
     pub fn udp_recv(pcb: *mut udp_pcb,
-                    recv: extern fn(arg: *mut c_void, upcb: *mut udp_pcb, p: *mut pbuf,
-                                    addr: *mut ip_addr, port: u16),
+                    recv: Option<extern fn(arg: *mut c_void, upcb: *mut udp_pcb, p: *mut pbuf,
+                                           addr: *mut ip_addr, port: u16)>,
                     recv_arg: *mut c_void);
 }

artiq/runtime.rs/liblwip/lib.rs

@@ -279,12 +279,12 @@ impl UdpSocket {
                 recv_buffer: LinkedList::new()
             }));
             let arg = &mut *state as *mut RefCell<UdpSocketState> as *mut _;
-            lwip_sys::udp_recv(raw, recv, arg);
+            lwip_sys::udp_recv(raw, Some(recv), arg);
             Ok(UdpSocket { raw: raw, state: state })
         }
     }
 
-    pub fn state(&self) -> *const RefCell<UdpSocketState> {
+    pub fn state(&self) -> &RefCell<UdpSocketState> {
         &*self.state
     }
 
@@ -376,12 +376,12 @@ impl TcpListener {
             }));
             let arg = &mut *state as *mut RefCell<TcpListenerState> as *mut _;
             lwip_sys::tcp_arg(raw2, arg);
-            lwip_sys::tcp_accept(raw2, accept);
+            lwip_sys::tcp_accept(raw2, Some(accept));
             Ok(TcpListener { raw: raw2, state: state })
         }
     }
 
-    pub fn state(&self) -> *const RefCell<TcpListenerState> {
+    pub fn state(&self) -> &RefCell<TcpListenerState> {
         &*self.state
     }
 
@@ -467,14 +467,14 @@ impl TcpStream {
             }));
             let arg = &mut *state as *mut RefCell<TcpStreamState> as *mut _;
             lwip_sys::tcp_arg(raw, arg);
-            lwip_sys::tcp_recv(raw, recv);
-            lwip_sys::tcp_sent(raw, sent);
-            lwip_sys::tcp_err(raw, err);
+            lwip_sys::tcp_recv(raw, Some(recv));
+            lwip_sys::tcp_sent(raw, Some(sent));
+            lwip_sys::tcp_err(raw, Some(err));
             TcpStream { raw: raw, state: state }
         }
     }
 
-    pub fn state(&self) -> *const RefCell<TcpStreamState> {
+    pub fn state(&self) -> &RefCell<TcpStreamState> {
         &*self.state
     }
 
@@ -536,6 +536,11 @@ impl TcpStream {
 impl Drop for TcpStream {
     fn drop(&mut self) {
         unsafe {
+            // lwip *will* try to call back after tcp_close
+            lwip_sys::tcp_recv(self.raw, None);
+            lwip_sys::tcp_sent(self.raw, None);
+            lwip_sys::tcp_err(self.raw, None);
+
             // tcp_close can fail here, but in drop() we don't care
             let _ = lwip_sys::tcp_close(self.raw);
         }

artiq/runtime.rs/src/kernel.rs

@@ -0,0 +1,37 @@
+use core::ptr;
+use board::csr::kernel_cpu;
+use mailbox;
+
+const KERNELCPU_EXEC_ADDRESS:    usize = 0x42000000;
+const KERNELCPU_PAYLOAD_ADDRESS: usize = 0x42020000;
+const KERNELCPU_LAST_ADDRESS:    usize = (0x4fffffff - 1024*1024);
+const KSUPPORT_HEADER_SIZE:      usize = 0x80;
+
+pub unsafe fn start() {
+    if kernel_cpu::reset_read() == 0 {
+        panic!("attempted to start kernel CPU when it is already running")
+    }
+
+    stop();
+
+    extern {
+        static _binary_ksupport_elf_start: ();
+        static _binary_ksupport_elf_end: ();
+    }
+    let ksupport_start = &_binary_ksupport_elf_start as *const _ as usize;
+    let ksupport_end   = &_binary_ksupport_elf_end as *const _ as usize;
+    ptr::copy_nonoverlapping(ksupport_start as *const u8,
+                             (KERNELCPU_EXEC_ADDRESS - KSUPPORT_HEADER_SIZE) as *mut u8,
+                             ksupport_end - ksupport_start);
+
+    kernel_cpu::reset_write(0);
+}
+
+pub fn stop() {
+    unsafe { kernel_cpu::reset_write(1) }
+    mailbox::acknowledge();
+}
+
+pub fn validate(ptr: usize) -> bool {
+    ptr >= KERNELCPU_EXEC_ADDRESS && ptr <= KERNELCPU_LAST_ADDRESS
+}

artiq/runtime.rs/src/kernel_proto.rs

@@ -0,0 +1,323 @@
+use std::io;
+use mailbox;
+use kernel;
+
+#[derive(Debug)]
+pub struct Exception<'a> {
+    pub name:     &'a str,
+    pub file:     &'a str,
+    pub line:     u32,
+    pub column:   u32,
+    pub function: &'a str,
+    pub message:  &'a str,
+    pub param:    [u64; 3],
+}
+
+pub use self::c::BacktraceItem;
+
+#[derive(Debug)]
+pub enum Message<'a> {
+    LoadRequest(&'a [u8]),
+    LoadReply   { error: Option<&'a str> },
+
+    NowInitRequest,
+    NowInitReply(u64),
+    NowSave(u64),
+
+    RunFinished,
+    RunException {
+        exception: Exception<'a>,
+        backtrace: &'a [BacktraceItem]
+    },
+
+    WatchdogSetRequest { ms: u64 },
+    WatchdogSetReply   { id: usize },
+    WatchdogClear      { id: usize },
+
+    RpcSend {
+        service: u32,
+        tag: &'a [u8],
+        data: *const *const ()
+    },
+    RpcRecvRequest {
+        slot: *mut ()
+    },
+    RpcRecvReply {
+        alloc_size: usize,
+        exception: Option<Exception<'a>>
+    },
+
+    CacheGetRequest { key: &'a str },
+    CacheGetReply   { value: &'static [u32] },
+    CachePutRequest { key: &'a str, value: &'static [u32] },
+    CachePutReply   { succeeded: bool },
+
+    Log(&'a str)
+}
+
+pub use self::Message::*;
+
+impl<'a> Message<'a> {
+    fn into_lower<R, F: FnOnce(*const ()) -> R>(self, f: F) -> R {
+        match self {
+            Message::LoadRequest(library) => {
+                let msg = c::LoadRequest {
+                    ty: c::Type::LoadRequest,
+                    library: library.as_ptr() as *const _
+                };
+                f(&msg as *const _ as *const _)
+            }
+
+            Message::NowInitReply(now) => {
+                let msg = c::NowInitReply {
+                    ty: c::Type::NowInitReply,
+                    now: now
+                };
+                f(&msg as *const _ as *const _)
+            }
+
+            other => panic!("Message::into_lower: {:?} unimplemented", other)
+        }
+    }
+
+    unsafe fn from_lower(ptr: *const ()) -> Self {
+        let msg = ptr as *const c::Message;
+        match (*msg).ty {
+            c::Type::LoadReply => {
+                let msg = ptr as *const c::LoadReply;
+                let error = if (*msg).error.is_null() {
+                    None
+                } else {
+                    Some(c::from_c_str((*msg).error))
+                };
+                Message::LoadReply { error: error }
+            }
+
+            c::Type::NowInitRequest => Message::NowInitRequest,
+            c::Type::NowSave => {
+                let msg = ptr as *const c::NowSave;
+                Message::NowSave((*msg).now)
+            }
+
+            c::Type::RunFinished => Message::RunFinished,
+
+            c::Type::Log => {
+                let msg = ptr as *const c::Log;
+                Message::Log(c::from_c_str_len((*msg).buf, (*msg).len))
+            }
+
+            ref other => panic!("Message::from_lower: {:?} unimplemented", other)
+        }
+    }
+
+    pub fn send_and_wait(self, waiter: ::sched::Waiter) -> io::Result<()> {
+        self.into_lower(|ptr| {
+            unsafe { mailbox::send(ptr as usize) }
+            waiter.until(mailbox::acknowledged)
+        })
+    }
+
+    pub fn wait_and_receive<R, F>(waiter: ::sched::Waiter, f: F) -> io::Result<R>
+            where F: FnOnce(Message<'a>) -> io::Result<R> {
+        try!(waiter.until(|| mailbox::receive() != 0));
+        if !kernel::validate(mailbox::receive()) {
+            return Err(io::Error::new(io::ErrorKind::InvalidData, "invalid kernel CPU pointer"))
+        }
+
+        let msg = unsafe { Self::from_lower(mailbox::receive() as *const ()) };
+        Ok(try!(f(msg)))
+    }
+
+    pub fn acknowledge() {
+        unsafe { mailbox::acknowledge() }
+    }
+}
+
+// Low-level representation, compatible with the C code in ksupport
+mod c {
+    use libc::{c_void, c_int, c_char, size_t};
+
+    #[repr(u32)]
+    #[derive(Debug)]
+    pub enum Type {
+        LoadRequest,
+        LoadReply,
+        NowInitRequest,
+        NowInitReply,
+        NowSave,
+        RunFinished,
+        RunException,
+        WatchdogSetRequest,
+        WatchdogSetReply,
+        WatchdogClear,
+        RpcSend,
+        RpcRecvRequest,
+        RpcRecvReply,
+        RpcBatch,
+        CacheGetRequest,
+        CacheGetReply,
+        CachePutRequest,
+        CachePutReply,
+        Log,
+    }
+
+    #[repr(C)]
+    #[derive(Debug)]
+    pub struct Message {
+        pub ty: Type
+    }
+
+    // kernel messages
+
+    #[repr(C)]
+    #[derive(Debug)]
+    pub struct LoadRequest {
+        pub ty: Type,
+        pub library: *const c_void,
+    }
+
+    #[repr(C)]
+    #[derive(Debug)]
+    pub struct LoadReply {
+        pub ty: Type,
+        pub error: *const c_char
+    }
+
+    #[repr(C)]
+    #[derive(Debug)]
+    pub struct NowInitReply {
+        pub ty: Type,
+        pub now: u64
+    }
+
+    #[repr(C)]
+    #[derive(Debug)]
+    pub struct NowSave {
+        pub ty: Type,
+        pub now: u64
+    }
+
+    #[repr(C)]
+    #[derive(Debug)]
+    pub struct RunException {
+        pub ty: Type,
+        pub exception: *const Exception,
+        pub backtrace: *const BacktraceItem,
+        pub backtrace_size: size_t
+    }
+
+    #[repr(C)]
+    #[derive(Debug)]
+    pub struct WatchdogSetRequest {
+        pub ty: Type,
+        pub ms: c_int
+    }
+
+    #[repr(C)]
+    #[derive(Debug)]
+    pub struct WatchdogSetReply {
+        pub ty: Type,
+        pub id: c_int
+    }
+
+    #[repr(C)]
+    #[derive(Debug)]
+    pub struct WatchdogClear {
+        pub ty: Type,
+        pub id: c_int
+    }
+
+    #[repr(C)]
+    #[derive(Debug)]
+    pub struct RpcSend {
+        pub ty: Type,
+        pub service: c_int,
+        pub tag: *const c_char,
+        pub data: *const *const c_void
+    }
+
+    #[repr(C)]
+    #[derive(Debug)]
+    pub struct RpcRecvRequest {
+        pub ty: Type,
+        pub slot: *mut c_void
+    }
+
+    #[repr(C)]
+    #[derive(Debug)]
+    pub struct RpcRecvReply {
+        pub ty: Type,
+        pub alloc_size: c_int,
+        pub exception: *const Exception
+    }
+
+    #[repr(C)]
+    #[derive(Debug)]
+    pub struct CacheGetRequest {
+        pub ty: Type,
+        pub key: *const c_char
+    }
+
+    #[repr(C)]
+    #[derive(Debug)]
+    pub struct CacheGetReply {
+        pub ty: Type,
+        pub length: size_t,
+        pub elements: *const u32
+    }
+
+    #[repr(C)]
+    #[derive(Debug)]
+    pub struct CachePutRequest {
+        pub ty: Type,
+        pub key: *const c_char,
+        pub length: size_t,
+        pub elements: *const u32
+    }
+
+    #[repr(C)]
+    #[derive(Debug)]
+    pub struct CachePutReply {
+        pub ty: Type,
+        pub succeeded: c_int
+    }
+
+    #[repr(C)]
+    #[derive(Debug)]
+    pub struct Log {
+        pub ty: Type,
+        pub buf: *const c_char,
+        pub len: size_t
+    }
+
+    // Supplementary structures
+
+    #[repr(C)]
+    #[derive(Debug)]
+    pub struct Exception {
+        pub name:     *const c_char, // or typeinfo
+        pub file:     *const c_char,
+        pub line:     u32,
+        pub column:   u32,
+        pub function: *const c_char,
+        pub message:  *const c_char,
+        pub param:    [u64; 3],
+    }
+
+    #[repr(C)]
+    #[derive(Debug)]
+    pub struct BacktraceItem {
+        pub function: usize,
+        pub offset: usize
+    }
+
+    pub unsafe fn from_c_str_len<'a>(ptr: *const c_char, len: size_t) -> &'a str {
+        use core::{str, slice};
+        str::from_utf8_unchecked(slice::from_raw_parts(ptr as *const u8, len))
+    }
+
+    pub unsafe fn from_c_str<'a>(ptr: *const c_char) -> &'a str {
+        extern { fn strlen(cs: *const c_char) -> size_t; }
+        from_c_str_len(ptr, strlen(ptr))
+    }
+}

artiq/runtime.rs/src/lib.rs

@@ -20,7 +20,10 @@ mod mailbox;
 
 mod logger;
 
+mod kernel_proto;
 mod session_proto;
+
+mod kernel;
 mod session;
 
 extern {
@@ -42,9 +45,10 @@ pub unsafe extern fn rust_main() {
         network_init();
 
         let mut scheduler = sched::Scheduler::new();
-        scheduler.spawn(4096, move |waiter| {
+        scheduler.spawn(8192, move |waiter| {
             session::handler(waiter, logger)
         });
+
         loop {
             lwip_service();
             scheduler.run()

artiq/runtime.rs/src/logger.rs

@@ -48,9 +48,9 @@ impl Log for BufferLogger {
         if self.enabled(record.metadata()) {
             use core::fmt::Write;
             writeln!(self.buffer.borrow_mut(), "{:>5}({}): {}",
-                     record.level(), record.location().module_path(), record.args()).unwrap();
+                     record.level(), record.target(), record.args()).unwrap();
             println!("{:>5}({}): {}",
-                     record.level(), record.location().module_path(), record.args());
+                     record.level(), record.target(), record.args());
         }
     }
 }

artiq/runtime.rs/src/mailbox.rs

@@ -1,14 +1,12 @@
 use core::ptr::{read_volatile, write_volatile};
 use board;
 
-const MAILBOX: *mut u32 = board::mem::MAILBOX_BASE as *mut u32;
-static mut last: u32 = 0;
+const MAILBOX: *mut usize = board::mem::MAILBOX_BASE as *mut usize;
+static mut last: usize = 0;
 
-pub fn send(data: u32) {
-    unsafe {
-        last = data;
-        write_volatile(MAILBOX, data)
-    }
+pub unsafe fn send(data: usize) {
+    last = data;
+    write_volatile(MAILBOX, data)
 }
 
 pub fn acknowledged() -> bool {
@@ -18,12 +16,7 @@ pub fn acknowledged() -> bool {
     }
 }
 
-pub fn send_and_wait(data: u32) {
-    send(data);
-    while !acknowledged() {}
-}
-
-pub fn receive() -> u32 {
+pub fn receive() -> usize {
     unsafe {
         let data = read_volatile(MAILBOX);
         if data == last {
@@ -37,15 +30,6 @@ pub fn receive() -> u32 {
     }
 }
 
-pub fn wait_and_receive() -> u32 {
-    loop {
-        let data = receive();
-        if data != 0 {
-            return data
-        }
-    }
-}
-
 pub fn acknowledge() {
     unsafe { write_volatile(MAILBOX, 0) }
 }

artiq/runtime.rs/src/sched.rs

@@ -104,8 +104,8 @@ impl Scheduler {
     }
 }
 
-#[derive(Debug)]
 enum WaitEvent {
+    Completion(*const (Fn() -> bool + 'static)),
     UdpReadable(*const RefCell<lwip::UdpSocketState>),
     TcpAcceptable(*const RefCell<lwip::TcpListenerState>),
     TcpWriteable(*const RefCell<lwip::TcpStreamState>),
@@ -115,6 +115,8 @@ enum WaitEvent {
 impl WaitEvent {
     fn completed(&self) -> bool {
         match *self {
+            WaitEvent::Completion(f) =>
+                unsafe { (*f)() },
             WaitEvent::UdpReadable(state) =>
                 unsafe { (*state).borrow().readable() },
             WaitEvent::TcpAcceptable(state) =>
@@ -127,12 +129,27 @@ impl WaitEvent {
     }
 }
 
+// *const DST doesn't have impl Debug
+impl ::core::fmt::Debug for WaitEvent {
+    fn fmt(&self, f: &mut ::core::fmt::Formatter) ->
+            ::core::result::Result<(), ::core::fmt::Error> {
+        write!(f, "WaitEvent...")
+    }
+}
+
 unsafe impl Send for WaitEvent {}
 
 #[derive(Debug, Clone, Copy)]
 pub struct Waiter<'a>(&'a Yielder<WaitResult, WaitRequest, OwnedStack>);
 
 impl<'a> Waiter<'a> {
+    pub fn relinquish(&self) {
+        self.0.suspend(WaitRequest {
+            timeout: None,
+            event:   None
+        });
+    }
+
     pub fn sleep(&self, duration: Duration) -> Result<()> {
         let request = WaitRequest {
             timeout: Some(Instant::now() + duration),
@@ -154,6 +171,13 @@ impl<'a> Waiter<'a> {
         }
     }
 
+    pub fn until<F: Fn() -> bool + 'static>(&self, f: F) -> Result<()> {
+        self.suspend(WaitRequest {
+            timeout: None,
+            event:   Some(WaitEvent::Completion(&f as *const _))
+        })
+    }
+
     pub fn udp_readable(&self, socket: &lwip::UdpSocket) -> Result<()> {
         self.suspend(WaitRequest {
             timeout: None,
@@ -239,6 +263,10 @@ impl<'a> UdpSocket<'a> {
         (&mut buf[..len]).copy_from_slice(&pbuf.as_slice()[..len]);
         Ok(len)
     }
+
+    pub fn readable(&self) -> bool {
+        self.lower.state().borrow().readable()
+    }
 }
 
 #[derive(Debug)]
@@ -265,6 +293,10 @@ impl<'a> TcpListener<'a> {
             buffer: None
         }, addr))
     }
+
+    pub fn acceptable(&self) -> bool {
+        self.lower.state().borrow().acceptable()
+    }
 }
 
 pub use self::lwip::Shutdown;
@@ -280,6 +312,14 @@ impl<'a> TcpStream<'a> {
     pub fn shutdown(&self, how: Shutdown) -> Result<()> {
         Ok(try!(self.lower.shutdown(how)))
     }
+
+    pub fn readable(&self) -> bool {
+        self.buffer.is_some() || self.lower.state().borrow().readable()
+    }
+
+    pub fn writeable(&self) -> bool {
+        self.lower.state().borrow().writeable()
+    }
 }
 
 impl<'a> Read for TcpStream<'a> {

artiq/runtime.rs/src/session.rs

@@ -1,12 +1,23 @@
 use std::prelude::v1::*;
 use std::str;
-use std::io::{self, Read, ErrorKind};
-use {config, rtio_crg};
+use std::io::{self, Read};
+use {config, rtio_crg, clock, mailbox, kernel};
 use logger::BufferLogger;
 use sched::{Waiter, TcpListener, TcpStream, SocketAddr, IP_ANY};
-use session_proto::*;
 
-#[derive(Debug, Clone, Copy)]
+use session_proto as host;
+use kernel_proto as kern;
+
+macro_rules! unexpected {
+    ($($arg:tt)*) => {
+        {
+            error!($($arg)*);
+            return Err(io::Error::new(io::ErrorKind::InvalidData, "protocol error"))
+        }
+    };
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
 enum KernelState {
     Absent,
     Loaded,
@@ -17,19 +28,16 @@ enum KernelState {
 #[derive(Debug)]
 pub struct Session {
     kernel_state: KernelState,
-}
-
-extern {
-    fn kloader_stop();
-    fn watchdog_init();
-    fn kloader_start_idle_kernel();
+    watchdog_set: clock::WatchdogSet,
+    now: u64
 }
 
 impl Session {
     pub fn new() -> Session {
-        unsafe { kloader_stop(); }
         Session {
-            kernel_state: KernelState::Absent
+            kernel_state: KernelState::Absent,
+            watchdog_set: clock::WatchdogSet::new(),
+            now: 0
         }
     }
 
@@ -41,16 +49,6 @@ impl Session {
     }
 }
 
-impl Drop for Session {
-    fn drop(&mut self) {
-        unsafe {
-            kloader_stop();
-            watchdog_init();
-            kloader_start_idle_kernel();
-        }
-    }
-}
-
 fn check_magic(stream: &mut TcpStream) -> io::Result<()> {
     const MAGIC: &'static [u8] = b"ARTIQ coredev\n";
 
@@ -63,89 +61,203 @@ fn check_magic(stream: &mut TcpStream) -> io::Result<()> {
     }
 }
 
-fn handle_request(stream: &mut TcpStream,
-                  logger: &BufferLogger,
-                  session: &mut Session) -> io::Result<()> {
-    fn read_request(stream: &mut TcpStream) -> io::Result<Request> {
-        let request = try!(Request::read_from(stream));
-        match &request {
-            &Request::LoadLibrary(_) => trace!("comm<-host LoadLibrary(...)"),
-            _ => trace!("comm<-host {:?}", request)
-        }
-        Ok(request)
+fn host_read(stream: &mut TcpStream) -> io::Result<host::Request> {
+    let request = try!(host::Request::read_from(stream));
+    match &request {
+        &host::Request::LoadLibrary(_) => trace!("comm<-host LoadLibrary(...)"),
+        _ => trace!("comm<-host {:?}", request)
     }
+    Ok(request)
+}
 
-    fn write_reply(stream: &mut TcpStream, reply: Reply) -> io::Result<()> {
-        trace!("comm->host {:?}", reply);
-        reply.write_to(stream)
+fn host_write(stream: &mut TcpStream, reply: host::Reply) -> io::Result<()> {
+    trace!("comm->host {:?}", reply);
+    reply.write_to(stream)
+}
+
+fn kern_send<'a>(waiter: Waiter, request: kern::Message<'a>) -> io::Result<()> {
+    match &request {
+        &kern::LoadRequest(_) => trace!("comm->kern LoadRequest(...)"),
+        _ => trace!("comm->kern {:?}", request)
     }
+    request.send_and_wait(waiter)
+}
 
-    match try!(read_request(stream)) {
-        Request::Ident =>
-            write_reply(stream, Reply::Ident(::board::ident(&mut [0; 64]))),
+fn kern_recv<R, F>(waiter: Waiter, f: F) -> io::Result<R>
+        where F: FnOnce(kern::Message) -> io::Result<R> {
+    kern::Message::wait_and_receive(waiter, |reply| {
+        trace!("comm<-kern {:?}", reply);
+        f(reply)
+    })
+}
+
+fn kern_acknowledge() -> io::Result<()> {
+    kern::Message::acknowledge();
+    Ok(())
+}
+
+fn comm_handle(waiter: Waiter,
+               stream: &mut TcpStream,
+               logger: &BufferLogger,
+               session: &mut Session) -> io::Result<()> {
+    match try!(host_read(stream)) {
+        host::Request::Ident =>
+            host_write(stream, host::Reply::Ident(::board::ident(&mut [0; 64]))),
 
         // artiq_corelog
-        Request::Log => {
+        host::Request::Log => {
             // Logging the packet with the log is inadvisable
             trace!("comm->host Log(...)");
             logger.extract(move |log| {
-                Reply::Log(log).write_to(stream)
+                host::Reply::Log(log).write_to(stream)
             })
         }
 
-        Request::LogClear => {
+        host::Request::LogClear => {
             logger.clear();
-            write_reply(stream, Reply::Log(""))
+            host_write(stream, host::Reply::Log(""))
         }
 
         // artiq_coreconfig
-        Request::FlashRead { ref key } => {
+        host::Request::FlashRead { ref key } => {
             let value = config::read_to_end(key);
-            write_reply(stream, Reply::FlashRead(&value))
+            host_write(stream, host::Reply::FlashRead(&value))
         }
 
-        Request::FlashWrite { ref key, ref value } => {
+        host::Request::FlashWrite { ref key, ref value } => {
             match config::write(key, value) {
-                Ok(_)  => write_reply(stream, Reply::FlashOk),
-                Err(_) => write_reply(stream, Reply::FlashError)
+                Ok(_)  => host_write(stream, host::Reply::FlashOk),
+                Err(_) => host_write(stream, host::Reply::FlashError)
             }
         }
 
-        Request::FlashRemove { ref key } => {
+        host::Request::FlashRemove { ref key } => {
             config::remove(key);
-            write_reply(stream, Reply::FlashOk)
+            host_write(stream, host::Reply::FlashOk)
         }
 
-        Request::FlashErase => {
+        host::Request::FlashErase => {
             config::erase();
-            write_reply(stream, Reply::FlashOk)
+            host_write(stream, host::Reply::FlashOk)
         }
 
         // artiq_run/artiq_master
-        Request::SwitchClock(clk) => {
+        host::Request::SwitchClock(clk) => {
             if session.running() {
-                error!("attempted to switch RTIO clock while kernel was running");
-                write_reply(stream, Reply::ClockSwitchFailed)
+                error!("attempted to switch RTIO clock while a kernel was running");
+                return host_write(stream, host::Reply::ClockSwitchFailed)
+            }
+
+            if rtio_crg::switch_clock(clk) {
+                host_write(stream, host::Reply::ClockSwitchCompleted)
             } else {
-                if rtio_crg::switch_clock(clk) {
-                    write_reply(stream, Reply::ClockSwitchCompleted)
-                } else {
-                    write_reply(stream, Reply::ClockSwitchFailed)
-                }
+                host_write(stream, host::Reply::ClockSwitchFailed)
             }
         }
 
-        _ => unreachable!()
+        host::Request::LoadLibrary(library) => {
+            if session.running() {
+                error!("attempted to load a new kernel while a kernel was running");
+                return host_write(stream, host::Reply::LoadFailed)
+            }
+
+            unsafe { kernel::start() }
+
+            try!(kern_send(waiter, kern::LoadRequest(&library)));
+            kern_recv(waiter, |reply| {
+                match reply {
+                    kern::LoadReply { error: None } => {
+                        session.kernel_state = KernelState::Loaded;
+                        host_write(stream, host::Reply::LoadCompleted)
+                    }
+                    kern::LoadReply { error: Some(cause) } => {
+                        error!("cannot load kernel: {}", cause);
+                        host_write(stream, host::Reply::LoadFailed)
+                    }
+                    other => unexpected!("unexpected reply from kernel CPU: {:?}", other)
+                }
+            })
+        }
+
+        host::Request::RunKernel => {
+            if session.kernel_state != KernelState::Loaded {
+                error!("attempted to run a kernel while not in Loaded state");
+                return host_write(stream, host::Reply::KernelStartupFailed)
+            }
+
+            session.kernel_state = KernelState::Running;
+            kern_acknowledge()
+        }
+
+        request => unexpected!("unexpected {:?}", request)
     }
 }
 
-fn handle_requests(stream: &mut TcpStream,
-                   logger: &BufferLogger) -> io::Result<()> {
+fn kern_handle(waiter: Waiter,
+               stream: &mut TcpStream,
+               session: &mut Session) -> io::Result<()> {
+    kern::Message::wait_and_receive(waiter, |request| {
+        match (&request, session.kernel_state) {
+            (&kern::LoadReply { .. }, KernelState::Loaded) |
+            (&kern::RpcRecvRequest { .. }, KernelState::RpcWait) => {
+                // We're standing by; ignore the message.
+                return Ok(())
+            }
+            (_, KernelState::Running) => (),
+            _ => {
+                unexpected!("unexpected request {:?} from kernel CPU in {:?} state",
+                            request, session.kernel_state)
+            }
+        }
+
+        trace!("comm<-kern {:?}", request);
+        match request {
+            kern::Log(log) => {
+                info!(target: "kernel", "{}", log);
+                kern_acknowledge()
+            }
+
+            kern::NowInitRequest =>
+                kern_send(waiter, kern::NowInitReply(session.now)),
+
+            kern::NowSave(now) => {
+                session.now = now;
+                kern_acknowledge()
+            }
+
+            request => unexpected!("unexpected {:?}", request)
+        }
+    })
+}
+
+fn handle(waiter: Waiter,
+          stream: &mut TcpStream,
+          logger: &BufferLogger) -> io::Result<()> {
     try!(check_magic(stream));
 
     let mut session = Session::new();
     loop {
-        try!(handle_request(stream, logger, &mut session))
+        if stream.readable() {
+            try!(comm_handle(waiter, stream, logger, &mut session))
+        }
+
+        if mailbox::receive() != 0 {
+            try!(kern_handle(waiter, stream, &mut session))
+        }
+
+        if session.kernel_state == KernelState::Running {
+            if session.watchdog_set.expired() {
+                try!(host_write(stream, host::Reply::WatchdogExpired));
+                return Err(io::Error::new(io::ErrorKind::Other, "watchdog expired"))
+            }
+
+            if !rtio_crg::check() {
+                try!(host_write(stream, host::Reply::ClockFailure));
+                return Err(io::Error::new(io::ErrorKind::Other, "RTIO clock failure"))
+            }
+        }
+
+        waiter.relinquish()
     }
 }
 
@@ -159,13 +271,13 @@ pub fn handler(waiter: Waiter,
         let (mut stream, addr) = listener.accept().unwrap();
         info!("new connection from {:?}", addr);
 
-        match handle_requests(&mut stream, logger) {
+        match handle(waiter, &mut stream, logger) {
             Ok(()) => (),
             Err(err) => {
-                if err.kind() == ErrorKind::UnexpectedEof {
+                if err.kind() == io::ErrorKind::UnexpectedEof {
                     info!("connection closed");
                 } else {
-                    error!("cannot handle network request: {:?}", err);
+                    error!("session aborted: {:?}", err);
                 }
             }
         }

artiq/runtime/Makefile

@@ -27,7 +27,7 @@ all: runtime.bin runtime.fbi
 %.fbi: %.bin
 	@echo " MSCIMG  " $@ && $(PYTHON) -m misoc.tools.mkmscimg -f -o $@ $<
 
-runtime.elf: $(OBJECTS) libartiq_rust.a
+runtime.elf: $(OBJECTS) libruntime.a
 	$(LD) $(LDFLAGS) \
 		--gc-sections \
 		-T $(RUNTIME_DIRECTORY)/runtime.ld \
@@ -40,7 +40,7 @@ runtime.elf: $(OBJECTS) libartiq_rust.a
 		-L../liballoc \
 		-L../liblwip \
 		-Lcargo/or1k-unknown-none/debug/ \
-		-lartiq_rust -lbase -lm -lcompiler-rt -lalloc -llwip
+		-lruntime -lbase -lm -lcompiler-rt -lalloc -llwip
 	@chmod -x $@
 
 ksupport.elf: $(OBJECTS_KSUPPORT)
@@ -60,7 +60,7 @@ ksupport.elf: $(OBJECTS_KSUPPORT)
 ksupport_data.o: ksupport.elf
 	$(LD) -r -b binary -o $@ $<
 
-libartiq_rust.a:
+libruntime.a:
 	CARGO_TARGET_DIR="./cargo" \
 		cargo rustc --verbose \
 			--manifest-path $(RUNTIME_DIRECTORY)/../runtime.rs/Cargo.toml \

artiq/runtime/kloader.c

@@ -167,7 +167,7 @@ void kloader_service_essential_kmsg(void)
             case MESSAGE_TYPE_LOG: {
                 struct msg_log *msg = (struct msg_log *)umsg;
 
-                core_log_va(msg->fmt, msg->args);
+                core_log("%s", msg->buf);
                 mailbox_acknowledge();
                 break;
             }