feat(kernel): add dump rt command (#375)

This adds a shell command that prints the state of the kernel's async
runtime.

src/rt.rs

@@ -9,7 +9,7 @@ use maitake::{
     scheduler::{self, StaticScheduler, Stealer},
     time,
 };
-use mycelium_util::sync::InitOnce;
+use mycelium_util::{fmt, sync::InitOnce};
 use rand::Rng;
 
 pub use maitake::task::JoinHandle;
@@ -95,6 +95,13 @@ pub fn init() {
     tracing::info!("kernel runtime initialized");
 }
 
+pub const DUMP_RT: crate::shell::Command = crate::shell::Command::new("rt")
+    .with_help("print the kernel's async runtime")
+    .with_fn(|_| {
+        tracing::info!(runtime = ?RUNTIME);
+        Ok(())
+    });
+
 static SCHEDULER: arch::LocalKey<Cell<Option<&'static StaticScheduler>>> =
     arch::LocalKey::new(|| Cell::new(None));
 
@@ -281,3 +288,14 @@ impl Runtime {
         self.cores[idx].try_get()?.try_steal().ok()
     }
 }
+
+impl fmt::Debug for Runtime {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let cores = self.active_cores();
+        f.debug_struct("Runtime")
+            .field("active_cores", &cores)
+            .field("cores", &&self.cores[..cores])
+            .field("injector", &self.injector)
+            .finish()
+    }
+}

src/shell.rs

@@ -46,6 +46,7 @@ pub fn eval(line: &str) {
                     tracing::info!(timer = ?crate::rt::TIMER);
                     Ok(())
                 }),
+            crate::rt::DUMP_RT,
             crate::arch::shell::DUMP_ARCH,
             Command::new("heap")
                 .with_help("print kernel heap statistics")