为什么老u-boot刷入新u-boot后再刷入自已后会无限重启？

u-boot无限重启中:

U-Boot 2012.04.01 (Mar 16 2016 - 10:53:44)

CPUID: 32440001
FCLK:      400 MHz
HCLK:      100 MHz
PCLK:       50 MHz
DRAM:  64 MiB


U-Boot 2012.04.01 (Mar 16 2016 - 10:53:44)

CPUID: 32440001
FCLK:      400 MHz
HCLK:      100 MHz
PCLK:       50 MHz
DRAM:  64 MiB


U-Boot 2012.04.01 (Mar 16 2016 - 10:53:44)

CPUID: 32440001
FCLK:      400 MHz
HCLK:      100 MHz
PCLK:       50 MHz
DRAM:  64 MiB


U-Boot 2012.04.01 (Mar 16 2016 - 10:53:44)

CPUID: 32440001
FCLK:      400 MHz
HCLK:      100 MHz
PCLK:       50 MHz
DRAM:  64 MiB




我是照着毕业班教程这样操作的，先用老的uboot下载新的uboot,再用新的uboot再下载自已，内存我都比较过了，没错，但重新上电就无限重启：

SMDK2410 # loady 33000000
## Ready for binary (ymodem) download to 0x33000000 at 115200 bps...
CCCCCCCCCC
Starting ymodem transfer.  Press Ctrl+C to cancel.
Transferring /work/system/u-boot-2012.04.01/u-boot.bin...
  100%     329 KB       9 KBfile:///C:usersrootTempV7(XMWRN]{G8~CI}BCCR3QC.gifc    00:00:35       0 Errors  

xyzModem - Cksum mode, 2640(SOH)/0(STX)/0(CAN) packets, 14 retries
## Total Size      = 0x00052698 = 337560 Bytes
SMDK2410 # protect off all
Un-Protect Flash Bank # 1
SMDK2410 # cmp.b 33000000 0 52698 //第一次比较nor flash 与sdram内容 相符
byte at 0x33000000 (0x13) != byte at 0x00000000 (0x14)
Total of 0 bytes were the same
SMDK2410 # erase 0 7ffff  

........... done
Erased 11 sectors
SMDK2410 # cp.b 33000000 0 80000
Copy to Flash... 9....8....7....6....5....4....3....2....1....done
SMDK2410 # cmp.b 33000000 0 80000  //第二次比较sdram与nor flash内容 相符
Total of 524288 bytes were the same
SMDK2410 #  
重新上电，无限重启。