start kernel failed

[li]

Hi all,
i am running kernel 2.4.18(hhl) with XPC850SR and everything is ok. But if i modified the 8xx_immap.h, add "utmode" unit in the io_port struct, after booting the board with ppcboot and tftp the kernel image(zImage.embedded under arch/ppc/boot/images), i use go #address to boot image, the console output start application at #address...
and nothing happened more!
If i comment the utmode unit, everything got back!
Any advice is encouraged!
Regards!
Li


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