run idle kernel on flash

artiq/firmware/runtime/main.rs

@@ -29,9 +29,10 @@ extern crate riscv;
 extern crate tar_no_std;
 
 use alloc::collections::BTreeMap;
-use core::cell::RefCell;
+use core::cell::{RefCell, Cell};
 use core::convert::TryFrom;
 use smoltcp::wire::HardwareAddress;
+use urc::Urc;
 
 use board_misoc::{csr, ident, clock, spiflash, config, net_settings, pmp, boot};
 #[cfg(has_ethmac)]
@@ -196,6 +197,7 @@ fn startup() {
 
     let ddma_mutex = sched::Mutex::new();
     let subkernel_mutex = sched::Mutex::new();
+    let restart_idle = Urc::new(Cell::new(false));
 
     let mut scheduler = sched::Scheduler::new(interface);
     let io = scheduler.io();
@@ -205,15 +207,18 @@ fn startup() {
     }
 
     rtio_mgt::startup(&io, &aux_mutex, &drtio_routing_table, &up_destinations, &ddma_mutex, &subkernel_mutex);
-
+    {
-    io.spawn(4096, mgmt::thread);
+        let restart_idle = restart_idle.clone();
+        io.spawn(4096, move |io| { mgmt::thread(io, &restart_idle) });
+    }
     {
         let aux_mutex = aux_mutex.clone();
         let drtio_routing_table = drtio_routing_table.clone();
         let up_destinations = up_destinations.clone();
         let ddma_mutex = ddma_mutex.clone();
         let subkernel_mutex = subkernel_mutex.clone();
-        io.spawn(32768, move |io| { session::thread(io, &aux_mutex, &drtio_routing_table, &up_destinations, &ddma_mutex, &subkernel_mutex) });
+        let restart_idle = restart_idle.clone();
+        io.spawn(32768, move |io| { session::thread(io, &aux_mutex, &drtio_routing_table, &up_destinations, &ddma_mutex, &subkernel_mutex, &restart_idle) });
     }
     #[cfg(any(has_rtio_moninj, has_drtio))]
     {

artiq/firmware/runtime/mgmt.rs

@@ -1,10 +1,12 @@
 use log::{self, LevelFilter};
+use core::cell::Cell;
 
 use io::{Write, ProtoWrite, Error as IoError};
 use board_misoc::{config, spiflash};
 use logger_artiq::BufferLogger;
 use mgmt_proto::*;
 use sched::{Io, TcpListener, TcpStream, Error as SchedError};
+use urc::Urc;
 
 impl From<SchedError> for Error<SchedError> {
     fn from(value: SchedError) -> Error<SchedError> {
@@ -12,7 +14,7 @@ impl From<SchedError> for Error<SchedError> {
     }
 }
 
-fn worker(io: &Io, stream: &mut TcpStream) -> Result<(), Error<SchedError>> {
+fn worker(io: &Io, stream: &mut TcpStream, restart_idle: &Urc<Cell<bool>>) -> Result<(), Error<SchedError>> {
     read_magic(stream)?;
     Write::write_all(stream, "e".as_bytes())?;
     info!("new connection from {}", stream.remote_endpoint());
@@ -84,7 +86,13 @@ fn worker(io: &Io, stream: &mut TcpStream) -> Result<(), Error<SchedError>> {
             }
             Request::ConfigWrite { ref key, ref value } => {
                 match config::write(key, value) {
-                    Ok(_)  => Reply::Success.write_to(stream),
+                    Ok(_)  => { 
+                        if key == "idle_kernel" {
+                            io.until(|| !restart_idle.get())?;
+                            restart_idle.set(true);
+                        }
+                        Reply::Success.write_to(stream)
+                    },
                     Err(_) => Reply::Error.write_to(stream)
                 }?;
             }
@@ -117,16 +125,17 @@ fn worker(io: &Io, stream: &mut TcpStream) -> Result<(), Error<SchedError>> {
     }
 }
 
-pub fn thread(io: Io) {
+pub fn thread(io: Io, restart_idle: &Urc<Cell<bool>>) {
     let listener = TcpListener::new(&io, 8192);
     listener.listen(1380).expect("mgmt: cannot listen");
     info!("management interface active");
 
     loop {
         let stream = listener.accept().expect("mgmt: cannot accept").into_handle();
+        let restart_idle = restart_idle.clone();
         io.spawn(4096, move |io| {
             let mut stream = TcpStream::from_handle(&io, stream);
-            match worker(&io, &mut stream) {
+            match worker(&io, &mut stream, &restart_idle) {
                 Ok(()) => (),
                 Err(Error::Io(IoError::UnexpectedEnd)) => (),
                 Err(err) => error!("aborted: {}", err)

artiq/firmware/runtime/session.rs

@@ -839,7 +839,7 @@ fn flash_kernel_worker(io: &Io, aux_mutex: &Mutex,
                        routing_table: &drtio_routing::RoutingTable,
                        up_destinations: &Urc<RefCell<[bool; drtio_routing::DEST_COUNT]>>,
                        ddma_mutex: &Mutex, subkernel_mutex: &Mutex, congress: &mut Congress,
-                       config_key: &str) -> Result<(), Error<SchedError>> {
+                       config_key: &str, restart_idle: Option<&Urc<Cell<bool>>>) -> Result<(), Error<SchedError>> {
     let mut session = Session::new(congress);
 
     config::read(config_key, |result| {
@@ -859,12 +859,17 @@ fn flash_kernel_worker(io: &Io, aux_mutex: &Mutex,
         }
     })?;
     kern_run(&mut session)?;
-
     loop {
         if !rpc_queue::empty() {
             unexpected!("unexpected background RPC in flash kernel")
         }
         
+        if let Some(r_idle) = restart_idle {
+            if r_idle.get() {
+                return Err(Error::KernelNotFound) 
+            }
+        }
+
         if mailbox::receive() != 0 {
             if process_kern_message(io, aux_mutex, routing_table, up_destinations, ddma_mutex, subkernel_mutex, None, &mut session)? {
                 return Ok(())
@@ -897,7 +902,7 @@ fn respawn<F>(io: &Io, handle: &mut Option<ThreadHandle>, f: F)
 pub fn thread(io: Io, aux_mutex: &Mutex,
         routing_table: &Urc<RefCell<drtio_routing::RoutingTable>>,
         up_destinations: &Urc<RefCell<[bool; drtio_routing::DEST_COUNT]>>,
-        ddma_mutex: &Mutex, subkernel_mutex: &Mutex) {
+        ddma_mutex: &Mutex, subkernel_mutex: &Mutex, restart_idle: &Urc<Cell<bool>>) {
     let listener = TcpListener::new(&io, 65535);
     listener.listen(1381).expect("session: cannot listen");
     info!("accepting network sessions");
@@ -910,7 +915,7 @@ pub fn thread(io: Io, aux_mutex: &Mutex,
         let mut congress = congress.borrow_mut();
         info!("running startup kernel");
         match flash_kernel_worker(&io, &aux_mutex, &routing_table, &up_destinations, 
-                ddma_mutex, subkernel_mutex, &mut congress, "startup_kernel") {
+                ddma_mutex, subkernel_mutex, &mut congress, "startup_kernel", None) {
             Ok(()) =>
                 info!("startup kernel finished"),
             Err(Error::KernelNotFound) =>
@@ -994,11 +999,13 @@ pub fn thread(io: Io, aux_mutex: &Mutex,
             let congress = congress.clone();
             let ddma_mutex = ddma_mutex.clone();
             let subkernel_mutex = subkernel_mutex.clone();
+            let restart_idle = restart_idle.clone();
+            restart_idle.set(false);
             respawn(&io, &mut kernel_thread, move |io| {
                 let routing_table = routing_table.borrow();
                 let mut congress = congress.borrow_mut();
                 match flash_kernel_worker(&io, &aux_mutex, &routing_table, &up_destinations, 
-                    &ddma_mutex, &subkernel_mutex, &mut *congress, "idle_kernel") {
+                    &ddma_mutex, &subkernel_mutex, &mut *congress, "idle_kernel", Some(&restart_idle)) {
                     Ok(()) =>
                         info!("idle kernel finished, standing by"),
                     Err(Error::Protocol(host::Error::Io(
@@ -1010,7 +1017,9 @@ pub fn thread(io: Io, aux_mutex: &Mutex,
                     }
                     Err(Error::KernelNotFound) => {
                         info!("no idle kernel found");
-                        while io.relinquish().is_ok() {}
+                        loop {
+                            if !io.relinquish().is_ok() || restart_idle.get() { break; }
+                        }
                     }
                     Err(err) => {
                         error!("idle kernel aborted: {}", err);