1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/buf.h b/kernel/buf.h
index 4616e9e..bbef407 100644
--- a/kernel/buf.h
+++ b/kernel/buf.h
@@ -8,5 +8,6 @@ struct buf {
   struct buf *prev; // LRU cache list
   struct buf *next;
   uchar data[BSIZE];
+  uint ticks;  // derived from global variable ticks (trap.c), record ticks when last modified
 };