suppress write() output after panic()

kernel/console.c

@@ -66,6 +66,12 @@ int
 consolewrite(int user_src, uint64 src, int n)
 {
   int i;
+  extern volatile int panicked; // from printf.c
+
+  if(panicked){
+    for(;;)
+      ;
+  }
 
   acquire(&cons.lock);
   for(i = 0; i < n; i++){

kernel/printf.c

@@ -121,7 +121,7 @@ panic(char *s)
   printf("panic: ");
   printf(s);
   printf("\n");
-  panicked = 1; // freeze other CPUs
+  panicked = 1; // freeze output from other CPUs
   for(;;)
     ;
 }