am335x在uboot使用TFTP时只能传输较小的文件，超过1M文件就会变得很慢，传输过程断断续续，导致无法使用TFTP加载内核，这可能由什么导致的，电脑和板子直连且在同一网段内，分别用Windows和虚拟机Ubuntu作为server端都是这种现象

=> tftp 0x80000000 uEnv.txt

**************_cpsw_init**************

link up on port 0, speed 100, full duplex

Using ethernet@4a100000device

TFTP from server 192.168.1.200; our IP address is 192.168.1.201 Filename 'uEnv.txt'.

Load address: 0x80000000

Loading: # 55.7 KiB/s done

Bytes transferred = 285 (11d hex)

=> tftp 0x80000000 MLO

**************_cpsw_init**************

link up on port 0, speed 100, full duplex Using ethernet@4a100000 device

TFTP from server 192.168.1.200; our IP address is 192.168.1.201 Filename 'MLO'.

Load address: 0x80000000

Loading: #

Abort

=> tftp 0x80000000 am335x-boneblack.dtb

**************_cpsw_init************** link up on port 0, speed 100, full duplex

Using ethernet@4a100000 device

TFTP from server 192.168.1.200; our IP address is 192.168.1.201 Filename 'am335x-boneblack.dtb'.

Load address: 0x80000000 Loading: #T T T T

Abort

=> tftp 0x80000000 am335x-boneblack.dtb

**************_cpsw_init************** link up on port 0, speed 100, full duplex

Using ethernet@4a100000 device

TFTP from server 192.168.1.200; our IP address is 192.168.1.201 Filename 'am335x-boneblack.dtb'.

Load address: 0x80000000

Loading: T #T T T #T T T T T #T T T