本人菜鸟一枚，在做国嵌实验手册上4-2-5实验网卡驱动移植后，编译u-boot时出现了如下错误，不知道什么原因，恳请高手指点一二，不胜感激！在做网卡驱动移植之前，u-boot是可以正确编译和运行的
et/libnet.a(net.o)(.text+0x1cc): In function `ArpRequest':
/home/uboot/u-boot-2009.08/net/net.c:250: undefined reference to `eth_send'
net/libnet.a(net.o)(.text+0x29c): In function `NetStartAgain':
/home/uboot/u-boot-2009.08/net/net.c:568: undefined reference to `eth_halt'
net/libnet.a(net.o)(.text+0x36c): In function `NetSendPacket':
/home/uboot/u-boot-2009.08/net/net.c:623: undefined reference to `eth_send'
net/libnet.a(net.o)(.text+0x630): In function `NetSendUDPPacket':
/home/uboot/u-boot-2009.08/net/net.c:668: undefined reference to `eth_send'
net/libnet.a(net.o)(.text+0x7f4): In function `PingTimeout':
/home/uboot/u-boot-2009.08/net/net.c:732: undefined reference to `eth_halt'
net/libnet.a(net.o)(.text+0xb70): In function `NetReceive':
/home/uboot/u-boot-2009.08/net/net.c:1295: undefined reference to `eth_send'
net/libnet.a(net.o)(.text+0xdfc):/home/uboot/u-boot-2009.08/net/net.c:1420: undefined reference to `eth_send'
net/libnet.a(net.o)(.text+0x11ac): In function `NetLoop':
/home/uboot/u-boot-2009.08/net/net.c:342: undefined reference to `eth_halt'
net/libnet.a(net.o)(.text+0x11b4):/home/uboot/u-boot-2009.08/net/net.c:346: undefined reference to `eth_init'
net/libnet.a(net.o)(.text+0x12e4):/home/uboot/u-boot-2009.08/net/net.c:370: undefined reference to `eth_halt'
