I create a FAT32 partition and ext4 partitions on sd card with MiniTool partition Wizard, and mount them under /mnt directory.
Then, copy /system partition to sdcard, by cp -a /system /mnt/system.
Finally, I extract the boot partition, modified the init file in ramdisk directory, repack and flash back to internal memory.
The mount info located in init.smdk4x12.rc as mount_all fstab.smdk4x12. So I modify the mount point of /system as sdcard partition.
The phone cannot boot, and stay at logo screen.
However, I use the same method to /cache and /data partitions, it works very well.
So, is there anything wrong with this method for /system partition?
Thanks for your help!!!