From 68a2145055dfbdf8a7038af7d202602f54d07a44 Mon Sep 17 00:00:00 2001
From: Eliza Weisman <eliza@buoyant.io>
Date: Thu, 1 Dec 2022 09:55:44 -0800
Subject: [PATCH] refac: move timer static from `arch` to `rt` (#375)

---
 src/arch/x86_64.rs           |  4 ----
 src/arch/x86_64/interrupt.rs |  7 ++-----
 src/arch/x86_64/shell.rs     |  5 -----
 src/lib.rs                   |  3 +++
 src/rt.rs                    | 16 ++++++++++++++--
 src/shell.rs                 |  8 ++++----
 6 files changed, 23 insertions(+), 20 deletions(-)

diff --git a/src/arch/x86_64.rs b/src/arch/x86_64.rs
index 2be21014..0da26af7 100644
--- a/src/arch/x86_64.rs
+++ b/src/arch/x86_64.rs
@@ -25,10 +25,6 @@ mod tests;
 
 pub type MinPageSize = mm::size::Size4Kb;
 
-pub fn tick_timer() {
-    interrupt::TIMER.advance_ticks(0);
-}
-
 #[cfg(target_os = "none")]
 bootloader::entry_point!(arch_entry);
 
diff --git a/src/arch/x86_64/interrupt.rs b/src/arch/x86_64/interrupt.rs
index 71d69e46..9fdf0eb6 100644
--- a/src/arch/x86_64/interrupt.rs
+++ b/src/arch/x86_64/interrupt.rs
@@ -25,8 +25,6 @@ pub fn enable_hardware_interrupts(acpi: Option<&acpi::InterruptModel>) {
     controller
         .start_periodic_timer(TIMER_INTERVAL)
         .expect("10ms should be a reasonable interval for the PIT or local APIC timer...");
-    time::set_global_timer(&TIMER)
-        .expect("`enable_hardware_interrupts` should only be called once!");
     tracing::info!(granularity = ?TIMER_INTERVAL, "global timer initialized")
 }
 
@@ -56,8 +54,7 @@ static TSS: sync::Lazy<task::StateSegment> = sync::Lazy::new(|| {
 
 pub(in crate::arch) static GDT: sync::InitOnce<Gdt> = sync::InitOnce::uninitialized();
 
-const TIMER_INTERVAL: time::Duration = time::Duration::from_millis(10);
-pub(super) static TIMER: time::Timer = time::Timer::new(TIMER_INTERVAL);
+pub const TIMER_INTERVAL: time::Duration = time::Duration::from_millis(10);
 
 static TEST_INTERRUPT_WAS_FIRED: AtomicUsize = AtomicUsize::new(0);
 
@@ -96,7 +93,7 @@ impl hal_core::interrupt::Handlers<Registers> for InterruptHandlers {
     }
 
     fn timer_tick() {
-        TIMER.pend_ticks(1);
+        crate::rt::TIMER.pend_ticks(1);
     }
 
     fn ps2_keyboard(scancode: u8) {
diff --git a/src/arch/x86_64/shell.rs b/src/arch/x86_64/shell.rs
index 1d488d6e..6bc31d76 100644
--- a/src/arch/x86_64/shell.rs
+++ b/src/arch/x86_64/shell.rs
@@ -18,8 +18,3 @@ pub const DUMP_ARCH: Command = Command::new("arch")
                 Ok(())
             }),
     ]);
-
-pub fn dump_timer(_: &str) -> Result<(), shell::Error> {
-    tracing::info!(timer = ?super::interrupt::TIMER);
-    Ok(())
-}
diff --git a/src/lib.rs b/src/lib.rs
index afd14063..a093000e 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -147,6 +147,9 @@ pub fn kernel_start(bootinfo: impl BootInfo, archinfo: crate::arch::ArchInfo) ->
     // tracing.
     arch::init(&bootinfo, &archinfo);
 
+    // initialize the kernel runtime.
+    rt::init();
+
     #[cfg(test)]
     arch::run_tests();
 
diff --git a/src/rt.rs b/src/rt.rs
index 793ee76a..7ad402fd 100644
--- a/src/rt.rs
+++ b/src/rt.rs
@@ -5,7 +5,10 @@ use core::{
     future::Future,
     sync::atomic::{AtomicBool, AtomicUsize, Ordering::*},
 };
-use maitake::scheduler::{self, StaticScheduler, Stealer};
+use maitake::{
+    scheduler::{self, StaticScheduler, Stealer},
+    time,
+};
 use mycelium_util::sync::InitOnce;
 use rand::Rng;
 
@@ -49,6 +52,8 @@ struct Runtime {
 /// 512 CPU cores ought to be enough for anybody...
 pub const MAX_CORES: usize = 512;
 
+pub static TIMER: time::Timer = time::Timer::new(arch::interrupt::TIMER_INTERVAL);
+
 static RUNTIME: Runtime = {
     // This constant is used as an array initializer; the clippy warning that it
     // contains interior mutability is not actually a problem here, since we
@@ -83,6 +88,13 @@ where
     })
 }
 
+/// Initialize the kernel runtime.
+pub fn init() {
+    time::set_global_timer(&TIMER).expect("`rt::init` should only be called once!");
+
+    tracing::info!("kernel runtime initialized");
+}
+
 static SCHEDULER: arch::LocalKey<Cell<Option<&'static StaticScheduler>>> =
     arch::LocalKey::new(|| Cell::new(None));
 
@@ -108,7 +120,7 @@ impl Core {
 
         // turn the timer wheel if it wasn't turned recently and no one else is
         // holding a lock, ensuring any pending timer ticks are consumed.
-        arch::tick_timer();
+        TIMER.advance_ticks(0);
 
         // if there are remaining tasks to poll, continue without stealing.
         if tick.has_remaining {
diff --git a/src/shell.rs b/src/shell.rs
index 4d223f4a..968695d0 100644
--- a/src/shell.rs
+++ b/src/shell.rs
@@ -42,10 +42,10 @@ pub fn eval(line: &str) {
                 .with_fn(|line| Err(Error::other(line, "not yet implemented"))),
             Command::new("timer")
                 .with_help("print the timer wheel")
-                .with_fn(crate::arch::shell::dump_timer),
-            Command::new("timer")
-                .with_help("print the timer wheel")
-                .with_fn(crate::arch::shell::dump_timer),
+                .with_fn(|_| {
+                    tracing::info!(timer = ?crate::rt::TIMER);
+                    Ok(())
+                }),
             crate::arch::shell::DUMP_ARCH,
             Command::new("heap")
                 .with_help("print kernel heap statistics")