添加DM9000网卡支持后，能ping通主机，无法TFTP下载文件，串口输出：
U-Boot 2009.08 ( 2鏈?19 2010 - 02:15:29)
DRAM: 64 MB
Flash: 2 MB
NAND: 128 MB
In: serial
Out: serial
Err: serial
Net: dm9000
[SMDK2440]# ping 192.168.1.8
dm9000 i/o: 0x20000300, id: 0x90000a46
DM9000: running in 16 bit mode
MAC: 08:00:3e:26:0a:5b
operating at unknown: 0 mode
Using dm9000 device
host 192.168.1.8 is alive
[SMDK2440]# tftp 0x30008000 zImage
dm9000 i/o: 0x20000300, id: 0x90000a46
DM9000: running in 16 bit mode
MAC: 08:00:3e:26:0a:5b
operating at unknown: 0 mode
Using dm9000 device
TFTP from server 192.168.1.8; our IP address is 192.168.1.15
Filename 'zImage'.
Load address: 0x30008000
Loading: T T T T T T T T T T
Retry count exceeded; starting again
dm9000 i/o: 0x20000300, id: 0x90000a46
DM9000: running in 16 bit mode
MAC: 08:00:3e:26:0a:5b
operating at unknown: 0 mode
Using dm9000 device
TFTP from server 192.168.1.8; our IP address is 192.168.1.15
Filename 'zImage'.
Load address: 0x30008000
Loading: T T T T T T T T T T
Retry count exceeded; starting again
dm9000 i/o: 0x20000300, id: 0x90000a46
DM9000: running in 16 bit mode
MAC: 08:00:3e:26:0a:5b
operating at unknown: 0 mode
Using dm9000 device
TFTP from server 192.168.1.8; our IP address is 192.168.1.15
Filename 'zImage'.
Load address: 0x30008000
Loading: T T T T T T T T T T
Retry count exceeded; starting again
dm9000 i/o: 0x20000300, id: 0x90000a46
DM9000: running in 16 bit mode
MAC: 08:00:3e:26:0a:5b
operating at unknown: 0 mode
Using dm9000 device
TFTP from server 192.168.1.8; our IP address is 192.168.1.15
Filename 'zImage'.
Load address: 0x30008000
Loading: T T T T T T T T T T
Retry count exceeded; starting again
dm9000 i/o: 0x20000300, id: 0x90000a46
DM9000: running in 16 bit mode
MAC: 08:00:3e:26:0a:5b
operating at unknown: 0 mode
Using dm9000 device
TFTP from server 192.168.1.8; our IP address is 192.168.1.15
Filename 'zImage'.
Load address: 0x30008000
Loading: T T T T T T T T T T
Retry count exceeded; starting again
dm9000 i/o: 0x20000300, id: 0x90000a46
DM9000: running in 16 bit mode
MAC: 08:00:3e:26:0a:5b
operating at unknown: 0 mode
........
