使用uboot當中的fdisk命令將硬盤份擴大后，如下所示:
root@iTOP4412-ubuntu-desktop:/media/U_eMMC# fdisk -l
Disk /dev/mmcblk0: 15.6 GB, 15634268160 bytes
255 heads, 63 sectors/track, 1900 cylinders, total 30535680 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Device Boot Start End Blocks Id System
/dev/mmcblk0p1 25837568 30515199 2338816 c W95 FAT32 (LBA)
/dev/mmcblk0p2 32768 24608767 12288000 83 Linux
/dev/mmcblk0p3 24608768 25223167 307200 83 Linux
/dev/mmcblk0p4 25223168 25837567 307200 83 Linux
可以看到/dev/mmcblk0p2 有12G多的空間。但是Ubunutu系統運行起來后只有2.6G。
使用SD卡啟動Ubuntu系統，將板卡上的eMMC掛載后，查看了一下:
root@iTOP4412-ubuntu-desktop:/media/U_eMMC/var/log/cups# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/root 2.6G 1.5G 1.1G 59% /
none 804M 4.0K 804M 1% /dev
none 161M 680K 161M 1% /run
none 5.0M 0 5.0M 0% /run/lock
none 804M 24K 804M 1% /run/shm
/dev/mmcblk0p2 2.6G 1.5G 1.1G 59% /media/U_eMMC
/dev/mmcblk0p2確實只有2.6G，不是磁盤空間上的12.3G。
怎么把2.6G的空間擴大呢？ 用一個命令 resize2fs
root@iTOP4412-ubuntu-desktop:/media/U_eMMC/var/log/cups# resize2fs /dev/mmcblk0p2 10G
resize2fs 1.42 (29-Nov-2011)
Filesystem at /dev/mmcblk0p2 is mounted on /media/U_eMMC; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 1
Performing an on-line resize of /dev/mmcblk0p2 to 2621440 (4k) blocks.
The filesystem on /dev/mmcblk0p2 is now 2621440 blocks long.
root@iTOP4412-ubuntu-desktop:/media/U_eMMC/var/log/cups#
root@iTOP4412-ubuntu-desktop:/media/U_eMMC/var/log/cups# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/root 2.6G 1.5G 1.1G 59% /
none 804M 4.0K 804M 1% /dev
none 161M 680K 161M 1% /run
none 5.0M 0 5.0M 0% /run/lock
none 804M 24K 804M 1% /run/shm
/dev/mmcblk0p2 9.9G 1.5G 8.0G 16% /media/U_eMMC
root@iTOP4412-ubuntu-desktop:/media/U_eMMC/var/log/cups#
擴大/dev/mmcblk0p2空間成功。
最后，重新從板卡上的/dev/mmcblk0p2啟動Ubuntu系統，啟動成功，查看剩余的空間，還有8G多。。完美。。