毕业班u-boot移植视频出现如图的错误该怎么办？

在ubuntu14中跟着毕业班u-boot移的视频做，上次能够操作成功，今天当修改u-boot支持Nand启动时出现如图所示的错误

drivers/i2c/libi2c.o drivers/input/libinput.o drivers/misc/libmisc.o drivers/mmc/libmmc.o drivers/mtd/libmtd.o drivers/mtd/nand/libnand.o drivers/mtd/onenand/libonenand.o drivers/mtd/spi/libspi_flash.o drivers/mtd/ubi/libubi.o drivers/net/libnet.o drivers/net/phy/libphy.o drivers/pci/libpci.o drivers/pcmcia/libpcmcia.o drivers/power/libpower.o drivers/rtc/librtc.o drivers/serial/libserial.o drivers/spi/libspi.o drivers/twserial/libtws.o drivers/u***/eth/libu***_eth.o drivers/u***/gadget/libu***_gadget.o drivers/u***/host/libu***_host.o drivers/u***/mu***/libu***_mu***.o drivers/u***/phy/libu***_phy.o drivers/u***/ulpi/libu***_ulpi.o drivers/video/libvideo.o drivers/watchdog/libwatchdog.o fs/cramfs/libcramfs.o fs/ext2/libext2fs.o fs/fat/libfat.o fs/fdos/libfdos.o fs/jffs2/libjffs2.o fs/reiserfs/libreiserfs.o fs/ubifs/libubifs.o fs/yaffs2/libyaffs2.o lib/libfdt/libfdt.o lib/libgeneric.o lib/lzma/liblzma.o lib/lzo/liblzo.o lib/zlib/libz.o net/libnet.o post/libpost.o board/samsung/smdk2440/libsmdk2440.o --end-group /work/u-boot_new/u-boot-2012.04.01/arch/ARM/lib/eabi_compat.o  -L /usr/local/arm/4.3.2/bin/../lib/gcc/arm-none-linux-gnueabi/4.3.2/armv4t -lgcc -Map u-boot.map -o u-boot
fs/yaffs2/libyaffs2.o: In function `yaffs_StartUp':
/work/u-boot_new/u-boot-2012.04.01/fs/yaffs2/yaffscfg.c:210: undefined reference to `nand_info'
make: *** [u-boot] Error 1

而且在修改文件的过程中没有修改过ysffs2相关个文件
求高手指点