在u-boot1.1.6中将内核(2.6.22及其以上版本)的调试串口改为2,系统竟然不能启动??

pcl001

在u-boot1.1.6中将内核(2.6.22及其以上版本)的调试串口改为2,系统竟然不能启动??
用串口0作为调试串口 , 能正常启动,原因何在??

请教大侠 :

启动参数:
#define CONFIG_BOOTARGS        "noinitrd root=/dev/mtdblock2 init=/linuxrc console=ttySAC2"

u-boot也配置为串口2输出信息

//#define CONFIG_SERIAL1          1    /* we use SERIAL 1 on SMDK2410 */
#define CONFIG_SERIAL3          1      /* we use SERIAL 1 on SMDK2410 */

启动信息:
U-Boot 1.1.6 (Jun 25 2009 - 15:54:41)
DRAM:  64 MB
Flash:  0 kB
NAND:  128 MiB
*** Warning - bad CRC or NAND, using default environment
In:    serial
Out:  serial
Err:  serial
UPLLVal [M:3ch,P:4h,S:2h]
MPLLVal [M:6eh,P:3h,S:1h]
CLKDIVN:5h

+---------------------------------------------+
| S3C2440A USB Downloader ver R0.03 2004 Jan  |
+---------------------------------------------+
USB: IN_ENDPOINT:1 OUT_ENDPOINT:3
FORMAT: <ADDR(DATA):4>+<SIZE(n+10):4>+<DATA:n>+<CS:2>
NOTE: Power off/on or press the reset button for 1 sec
      in order to get a valid USB device address.
Hit any key to stop autoboot:  0
Booting Linux ...
NAND read: device 0 offset 0x60000, size 0x200000
Reading data from 0x25f800 -- 100% complete.
2097152 bytes read: OK
## Booting image at 30007fc0 ...
  Image Name:  Linux-2.6.22.6
  Created:      2009-06-25  2:32:07 UTC
  Image Type:  ARM Linux Kernel Image (uncompressed)
  Data Size:    1584708 Bytes =  1.5 MB
  Load Address: 30008000
  Entry Point:  30008000
  Verifying Checksum ... OK
  XIP Kernel Image ... OK
Starting kernel ...

到Starting kernel ...就走不下去那


在内核2.6.13中, 照上面更改(调试串口2)能正常启动, 请教大侠怎样判断问题