Merge branch 'IOTSYSTOOL-1290' into custom_target_filename

Author: Juho Hovila

mbed_flasher/flashers/FlasherMbed.py

@@ -220,9 +220,14 @@ def _copy_file_windows(self, source, destination):
     def _copy_file(self, aux_source, destination):
         destination_fd = None
         try:
-            destination_fd = os.open(
-                destination,
-                os.O_CREAT | os.O_TRUNC | os.O_RDWR | os.O_SYNC)
+            if os.uname()[4].startswith('arm'):
+                destination_fd = os.open(
+                    destination,
+                    os.O_CREAT | os.O_TRUNC | os.O_RDWR | os.O_DIRECT)
+            else:
+                destination_fd = os.open(
+                    destination,
+                    os.O_CREAT | os.O_TRUNC | os.O_RDWR | os.O_SYNC)
 
             self.logger.debug("Copying binary: %s (size=%i bytes)", destination, len(aux_source))
             os.write(destination_fd, aux_source)