用sd卡启动，烧写uboot，出现错误如图，什么原因，请大神指教

NAND write: device 0 offset 0x280000, size 0x95c54
Writting at 0x315c54 -- 100% complete.
613460 bytes written: OK
ini_upgrade_linux:setName=linux_upgrade,keyName=system,keyVal=rootfs_4k.img
reading rootfs_4k.img
** Unable to read file rootfs_4k.img **

NAND erase.part: device 0 offset 0xc80000, size 0x3f380000
Erasing at 0x3ffc0000 -- 100% complete.
OK

NAND write: device 0 offset 0xc80000, size 0x95c54
Writting at 0xd15c54 -- 100% complete.
613460 bytes written: OK
Erasing NAND...
Erasing at 0x200000 -- 100% complete.
Writing to NAND... OK
Booting from nand ...
setting bootargs ...
bootargs=console=ttySAC0,115200n8 androidboot.console=ttySAC0 ubi.mtd=9 root=ubi0:rootfs rootfstype=ubifs rw rootwait=1 rw rootwait=1 init=/init ip=off lcd=X800Y480 uart1_d_can=uart1 uart2_i2c2=uart2

NAND read: device 0 offset 0x780000, size 0x500000
5242880 bytes read: OK
Bad Linux ARM zImage magic!
## Error: "bootcmd_nand(" not defined