xen console: update the "to be written" count

bindings/xen/console.c

@@ -108,7 +108,7 @@ void console_write(const char *buf, size_t len)
     do
     {
         /* Try and put some data into the ring. */
-        written = console_write_some(&buf[written], len - written);
+        written += console_write_some(&buf[count], len);
 
         /* Signal xenconsoled that new data is available. */
         hypercall_evtchn_send(console_evtchn);
@@ -122,7 +122,6 @@ void console_write(const char *buf, size_t len)
             while (ACCESS_ONCE(console_ring->out_cons) == cons)
                 hypercall_yield();
         }
-
     } while (written < len);
 
     /* Wait for xenconsoled to consume all the data we gave. */