http://www.unixresources.net/linux/clf/embedded/archive/00/00/62/23/622399.html
http://blogold.chinaunix.net/u/31100/showart_244622.html
限制512m内存之后就可以跑起来，奇怪啊！
setenv bootcmd 'setenv bootargs init=/sbin/init ip=192.168.73.59:192.168.73.1:192.168.73.1:255.255.255.0:target:eth0:off console=ttyS0,115200 console=tty1 mtdparts=spi_flash:0x100000@0(uboot),0x700000@0x100000(linux-root) mac=00:11:65:34:43:22 video=dovefb:lcd0:$(lcd0_params) clcd.lcd0_enable=$(lcd0_enable) mem=512m; sflash read 0x100000 $(loadaddr) 0x500000; bootm $(loadaddr);'