uboot通过添加指令自动启动内核

我的uboot始终有些问题，总是不能自动启动内核（对uboot搞的还不太懂），内核烧到nand flash中，uboot不能自动启动，最后发现uboot中有一个nboot指令，可以将nand flash中的内容加载到sdram中，于是我把这个指令加到了uboot/include/configs/*.h中：
*是你板子的名字
在这里以sbc2410x.h为例 

#define CONFIG_BOOTDELAY    3
#define CONFIG_BOOTARGS        "console=ttySAC0 root=/dev/nfs nfsroot=192.168.0.1:/friendly-arm/rootfs_netserv ip=192.168.0.69:192.168.0.1:192.168.0.1:255.255.255.0:debian:eth0:off"
#define CONFIG_ETHADDR            08:00:3e:26:0a:5b
#define CONFIG_NETMASK          255.255.255.0
#define CONFIG_IPADDR        192.168.0.69
#define CONFIG_SERVERIP        192.168.0.1
/*#define CONFIG_BOOTFILE    "elinos-lart" */
// #define CONFIG_BOOTCOMMAND    "dhcp; bootm"
#define CONFIG_BOOTCOMMAND    "nboot 0x30400000 0 0x60000\;bootm"

将红的是注释掉，加上蓝的。
其中nboot是uboot指令－－将nand flash中的内容加载到sdram中，0x30400000是拷到的sdram的地址，0是nand flash设备号，0x60000是内核在nand flash的地址。在通过bootm从0x30400000启动内核。
虽然这样是可以自动启动内核了，但是这样还存在一些问题，会显示两次启动信息：

Loading from device 0: <NULL> at 0x4e000000 (offset 0x60000)                   
                                                                               
   Image Name:   Linux-2.6.13-utulinux2440                                     
                                                                               
   Created:      2007-11-04   6:37:51 UTC                                      
                                                                               
   Image Type:   ARM Linux Kernel Image (gzip compressed)                      
                                                                               
   Data Size:    1477940 Bytes =  1.4 MB                                       
                                                                               
   Load Address: 30008000                                                      
                                                                               
   Entry Point:  30008000                                                      
                                                                               
## Booting image at 30400000 ...                                               
                                                                               
   Image Name:   Linux-2.6.13-utulinux2440                                     
                                                                               
   Created:      2007-11-04   6:37:51 UTC                                      
                                                                               
   Image Type:   ARM Linux Kernel Image (gzip compressed)                      
                                                                               
   Data Size:    1477940 Bytes =  1.4 MB                                       
                                                                               
   Load Address: 30008000                                                      
                                                                               
   Entry Point:  30008000                                                      
                                                                               
   Verifying Checksum ... OK                                                   
                                                                               
   Uncompressing Kernel Image ... OK                                           
                                                                               
                                                                               
                                                                               
Starting kernel ...                     

这个问题有待进一步解决。。。