1. Android升級到較新的版本後，想用.zip升級包升回舊的版本時，在升級時會發錯。這是由於android系統時對升級檔案有版本檢測。

2. build/tools/releasetools/ota_from_target_files:

def main(argv):

  def option_handler(o, a):
    if o == "--board_config":
      pass   # deprecated
    elif o in ("-k", "--package_key"):
      OPTIONS.package_key = a
    elif o in ("-i", "--incremental_from"):
      OPTIONS.incremental_source = a
    elif o in ("-w", "--wipe_user_data"):
      OPTIONS.wipe_user_data = True
    elif o in ("-n", "--no_prereq"):
      OPTIONS.omit_prereq = True
    elif o in ("-o", "--oem_settings"):
      OPTIONS.oem_source = a
    elif o in ("-e", "--extra_script"):
      OPTIONS.extra_script = a
    elif o in ("-a", "--aslr_mode"):
      if a in ("on", "On", "true", "True", "yes", "Yes"):
        OPTIONS.aslr_mode = True
      else:
        OPTIONS.aslr_mode = False
    elif o in ("-t", "--worker_threads"):
 

3. build/tools/releasetools/edify_generator.py 比較時間戳就是在這裡

  def AssertOlderBuild(self, timestamp, timestamp_text):
    """Assert that the build on the device is older (or the same as)
    the given timestamp."""
    self.script.append(
        ('(!less_than_int(%s, getprop("ro.build.date.utc"))) || '
         'abort("Can\'t install this package (%s) over newer '
         'build (" + getprop("ro.build.date") + ").");'
         ) % (timestamp, timestamp_text))

4. 如果不想系統檢測版本，將ota_from_target_files檔案中改為OPTIONS.omit_prereq = False