U-Boot 2014.07 (Oct 09 2015 - 22:29:06)
I2C: ready
DRAM: 512 MiB
NAND: 1024 MiB
MMC: OMAP SD/MMC: 0, OMAP SD/MMC: 1
reading uboot.env
** Unable to read "uboot.env" from mmc0:1 **
Using default environment
Net: <ethaddr> not set. Validating first E-fuse MAC
cpsw, usb_ether
Hit any key to stop autoboot: 0
WARNING: Could not determine device tree to use
switch to partitions #0, OK
mmc0 is current device
SD/MMC found on device 0
reading uEnv.txt
** Unable to read file uEnv.txt **
4337552 bytes read in 307 ms (13.5 MiB/s)
** File not found /boot/undefined **
Kernel image @ 0x82000000 [ 0x000000 - 0x422f90 ]
Starting kernel ...
SD卡启动时卡在这了，并会自动这样循环，请求高手指点
