Incorporate new understanding of/with Intel SMP spec.

Dropped cmpxchg in favor of xchg, to match lecture notes.

Use xchg to release lock, for future protection and to
keep gcc from acting clever.

1 files changed, 2 insertions, 1 deletions

diff --git a/main.c b/main.c
index 2108d95..6ec6d19 100644
--- a/main.c
+++ b/main.c
@@ -50,8 +50,9 @@ mpmain(void)
   if(cpu() != mp_bcpu())
     lapic_init(cpu());
   setupsegs(0);
-  cpus[cpu()].booted = 1;
+  xchg(&cpus[cpu()].booted, 1);
 
+  cprintf("cpu%d: scheduling\n");
   scheduler();
 }