网口可以检测到，但无法ping通 ，有谁知道为什么吗？
U-Boot 2013.01.01-svn131 (Apr 28 2015 - 15:18:02)
I2C: ready
DRAM: 512 MiB
WARNING: Caches not enabled
board_init
NAND: 1024 MiB
MMC: OMAP SD/MMC: 0, OMAP SD/MMC: 1
ERROR: import c0750930= f2907ce8
at env_common.c:174/env_import()
*** Warning - bad CRC, using default environment
musb-hdrc: ConfigData=0xde (UTMI-8, dyn FIFOs, bulk combine, bulk split, HB-ISO Rx, HB-ISO Tx, SoftConn)
musb-hdrc: MHDRC RTL version 2.0
musb-hdrc: setup fifo_mode 4
musb-hdrc: 28/31 max ep, 16384/16384 memory
USB Peripheral mode controller at 47401000 using PIO, IRQ 0
musb-hdrc: ConfigData=0xde (UTMI-8, dyn FIFOs, bulk combine, bulk split, HB-ISO Rx, HB-ISO Tx, SoftConn)
musb-hdrc: MHDRC RTL version 2.0
musb-hdrc: setup fifo_mode 4
musb-hdrc: 28/31 max ep, 16384/16384 memory
USB Host mode controller at 47401800 using PIO, IRQ 0
Net: mac 54 4a 16 c0 e5 55
<ethaddr> not set. Validating first E-fuse MAC
cpsw
Hit any key to stop autoboot: 0
Card did not respond to voltage select!
mmc0(part 0) is current device
Card did not respond to voltage select!
Booting from nand ...
NAND read: device 0 offset 0x280000, size 0x500000
5242880 bytes read: OK
Wrong Image Format for bootm command
ERROR: can't get kernel image!
U-Boot# setenv ipaddr 172.16.45.200
U-Boot# setenv netmask 255.255.255.0
U-Boot# ping 172.16.45.31
link up on port 0, speed 100, full duplex
Using cpsw device
ping failed; host 172.16.45.31 is not alive
U-Boot# dhcp
link up on port 0, speed 100, full duplex
BOOTP broadcast 1
## Warning: gatewayip needed but not set
BOOTP broadcast 2
## Warning: gatewayip needed but not set
BOOTP broadcast 3
BOOTP broadcast 4
## Warning: gatewayip needed but not set
