klog: [ssss.mmm] millisecond timestamps from the PIT

- interrupts::uptime_ms(): monotonic ms since boot — the 100 Hz PIT
  tick (10 ms) plus interpolation from the PIT's live 1.19 MHz
  down-counter (read twice around the tick load; a count jump means a
  tick fired between reads) for true sub-ms resolution.  TICKS widened
  AtomicU16 -> AtomicU64 (u16 wrapped after ~11 min).
- PIT_READY gates interpolation until interrupts::init configures the
  timer, so early-boot lines are deterministically [0000.000] instead
  of uninitialised-PIT noise; klog clamps timestamps monotonic.
- The CMOS RTC cannot provide milliseconds (1 Hz BCD device, seconds
  only) — millis come from the PIT.
- klog stores ms per line at append time; dump format is now
  '[0000.123] 000000  === rsnix boot ===' (user-specified format).

Verified in QEMU: first line [0000.000], Phase-2 lines show real
monotonic ms (fs: vfs ready at [0000.519], self-test [0000.524]),
per-dump monotonicity, boot.log persists timestamps, test-disk round
trip fsck-clean.

1 files changed, 9 insertions, 3 deletions

diff --git a/rsnix/src/vt.rs b/rsnix/src/vt.rs
index 709ea71..53821b7 100644
--- a/rsnix/src/vt.rs
+++ b/rsnix/src/vt.rs
@@ -224,7 +224,13 @@ fn put_byte(b: u8) {
 }
 
 fn param(i: usize, default: usize) -> usize {
-    unsafe { if i < NPARAMS { PARAMS[i] } else { default } }
+    unsafe {
+        if i < NPARAMS {
+            PARAMS[i]
+        } else {
+            default
+        }
+    }
 }
 
 /// Place a printable glyph at the cursor and advance (wrapping/scrolling).
@@ -409,7 +415,7 @@ fn newline() {
 /// only the newly-exposed rows.
 const SCROLL_BATCH: usize = 16;
 static mut PENDING_SCROLLS: usize = 0;
-static mut LAST_SYNC_TICK: u16 = 0;
+static mut LAST_SYNC_TICK: u64 = 0;
 
 /// Shift the logical grid up one row; defer the framebuffer shift.
 fn scroll_up() {
@@ -424,7 +430,7 @@ fn scroll_up() {
         // Batch: sync when enough scrolls piled up, or when the stream
         // pauses (~40 ms at the 100 Hz timer) so interactive output still
         // appears promptly.
-        const TICK_LIMIT: u16 = 4;
+        const TICK_LIMIT: u64 = 4;
         let now = crate::interrupts::TICKS.load(core::sync::atomic::Ordering::Relaxed);
         if PENDING_SCROLLS >= SCROLL_BATCH || now.wrapping_sub(LAST_SYNC_TICK) > TICK_LIMIT {
             sync_scroll();