With only RISCV64-I extension

1 files changed, 8 insertions, 3 deletions

diff --git a/kernel/spinlock.c b/kernel/spinlock.c
index 9840302..9603578 100644
--- a/kernel/spinlock.c
+++ b/kernel/spinlock.c
@@ -25,18 +25,23 @@ acquire(struct spinlock *lk)
   if(holding(lk))
     panic("acquire");
 
+  // TODO This depends on a macro that is only available in the Atomic extension that is
+  // not being implemented. Fix this.
+  // When NCPU is set to 1 (as is currently the case), disabling this shouldn't make a difference.
+  
   // On RISC-V, sync_lock_test_and_set turns into an atomic swap:
   //   a5 = 1
   //   s1 = &lk->locked
   //   amoswap.w.aq a5, a5, (s1)
-  while(__sync_lock_test_and_set(&lk->locked, 1) != 0)
-    ;
+  while (lk->locked == 1);
+  lk->locked = 1;  
+  /* while(__sync_lock_test_and_set(&lk->locked, 1) != 0); */
 
   // Tell the C compiler and the processor to not move loads or stores
   // past this point, to ensure that the critical section's memory
   // references happen strictly after the lock is acquired.
   // On RISC-V, this emits a fence instruction.
-  __sync_synchronize();
+  /* __sync_synchronize(); */
 
   // Record info about lock acquisition for holding() and debugging.
   lk->cpu = mycpu();