def get_block_devices(bdms=None):
    """
    @type bdms: list
    """
    ret = ''
    if bdms:
        for bdm in bdms:
            ret += '{0}\n'.format(bdm.get('DeviceName', '-'))
            ebs = bdm.get('Ebs')
            if ebs:
                ret += ' Status: {0}\n'.format(ebs.get('Status', '-'))
                ret += ' Snapshot Id: {0}\n'.format(ebs.get('SnapshotId', '-'))
                ret += ' Volume Size: {0}\n'.format(ebs.get('VolumeSize', '-'))
                ret += ' Volume Type: {0}\n'.format(ebs.get('VolumeType', '-'))
                ret += ' Encrypted: {0}\n'.format(str(ebs.get('Encrypted',
                    '-')))
                ret += ' Delete on Termination: {0}\n'.format(ebs.get(
                    'DeleteOnTermination', '-'))
                ret += ' Attach Time: {0}\n'.format(str(ebs.get(
                    'AttachTime', '-')))
        return ret.rstrip()
    else:
        return ret
