/***********************************************************************
 *                       I.MX6 32G SD卡测试
 * 说明：
 *     这是刘涛测试32G卡的情况。
 * 
 *                                    2016-10-17 深圳 南山平山村 曾剑锋
 **********************************************************************/

一、参考文档：
    [solved] couldn‘t mount because of unsupported optional
        https://forums.gentoo.org/viewtopic-p-7259024.html

二、32G SD卡挂载情况测试：
    1. fat     
        ok
    2. ext2    
        ok
    3. ext3    
        root@freescale ~$ mount -t ext3 /dev/mmcblk1p1
        root@freescale ~$ mount /dev/mmcblk1p1 /mnt/mount/
        root@freescale ~$ mount -t ext3 /dev/mmcblk1p1 /mnt/mount/
        EXT3-fs: barriers not enabled
        kjournald starting.  Commit interval 5 seconds
        EXT3-fs (mmcblk1p1): using internal journal
        EXT3-fs (mmcblk1p1): mounted filesystem with writeback data mode
    4. ext4    
        root@freescale ~$ mount /dev/mmcblk1p1 /mnt/mount/
        EXT3-fs (mmcblk1p1): error: couldn‘t mount because of unsupported optional features (240)
        EXT2-fs (mmcblk1p1): error: couldn‘t mount because of unsupported optional features (240)
        EXT4-fs (mmcblk1p1): mounted filesystem with ordered data mode. Opts: (null)