板子启动信息如下：
U-Boot 2015.07 (Dec 09 2015 - 23:34:09 +0800)
Model: Zynq Zed Development Board
DRAM: ECC disabled 512 MiB
MMC: zynq_sdhci: 0
SF: Detected S25FL256S_64K with page size 256 Bytes, erase size 64 KiB, total 32
MiB
*** Warning - bad CRC, using default environment
In: serial
Out: serial
Err: serial
Model: Zynq Zed Development Board
Net: Gem.e000b000
Hit any key to stop autoboot: 0
Device: zynq_sdhci
Manufacturer ID: 41
OEM: 3432
Name: SD8GB
Tran Speed: 50000000
Rd Block Len: 512
SD version 2.0
High Capacity: Yes
Capacity: 7.4 GiB
Bus Width: 4-bit
Erase Group Size: 512 Bytes
reading uEnv.txt
** Unable to read file uEnv.txt **
Copying Linux from SD to RAM...
reading uImage
** Unable to read file uImage **
zynq-uboot>
