Linux kernel for A20 cpu stuck at 'Starting kernel' - linux-kernel

Question

Linux kernel version: 4.1.8
board:cubietruck with A20 CPU.
compiled platform: os x 10.5.5
I do as follows:
First I use sunxi_defconfig as the default configuration, but 'byte_swap.h' not found error occurred. Then I use a sun7i_defconfig which offered by cubieboard, and then make -j4 ARCH=arm CROSS_COMPILE=arm-none-eabi- zImage,make -j4 ARCH=arm CROSS_COMPILE=arm-none-eabi- dtbs.
Then I burn the Uboot and the spl to the SDCard and make to partitions: one for boot and one for root file system. I put the zImage, script.bin and the dtb file on the boot partition.
Then I create boot.cmd as below:
fatload mmc 0 0x46000000 zImage
fatload mmc 0 0x49000000 sun7i-a20-cubietruck.dtb
setenv bootargs console=ttyS0,115200 earlyprintk root=/dev/mmcblk0p2 rootwait panic=10 ${extra}
bootz 0x46000000 - 0x49000000
and then mkimage -C none -A arm -T script -d boot.cmd boot.scr.
so there's three files on the boot partition:
boot.scr
script.bin
sun7i-a20-cubietruck.dtb
zImage
the Uboot works fine.(At least I think), here is the output
U-Boot SPL 2014.04 (Sep 29 2015 - 21:36:09)
Board: Cubietruck
DRAM: 2048 MiB
CPU: 960000000Hz, AXI/AHB/APB: 3/2/2
spl: not an uImage at 1600
U-Boot 2014.04 (Sep 29 2015 - 21:36:09) Allwinner Technology
CPU: Allwinner A20 (SUN7I)
Board: Cubietruck
I2C: ready
DRAM: 2 GiB
MMC: SUNXI SD/MMC: 0
*** Warning - bad CRC, using default environment
In: serial
Out: serial
Err: serial
Net: dwmac.1c50000
Hit any key to stop autoboot: 0
reading uEnv.txt
** Unable to read file uEnv.txt **
Failed to mount ext2 filesystem...
** Unrecognized filesystem type **
Failed to mount ext2 filesystem...
** Unrecognized filesystem type **
reading boot.scr
281 bytes read in 16 ms (16.6 KiB/s)
Jumping to boot.scr
## Executing script at 44000000
reading zImage
3446280 bytes read in 192 ms (17.1 MiB/s)
reading sun7i-a20-cubietruck.dtb
26288 bytes read in 30 ms (855.5 KiB/s)
Kernel image # 0x46000000 [ 0x000000 - 0x349608 ]
## Flattened Device Tree blob at 49000000
Booting using the fdt blob at 0x49000000
Loading Device Tree to 4fff6000, end 4ffff6af ... OK
Starting kernel ...
Any one could help?