XPC850SR from 48M to 80M

Hi all,
i am going to raise xpc850SR freq from 48M to 80M.
with the ppcboot-1.1.6, i still set the freq to 48M,
and i change the freq to 80M in linux kernel file m8xx_setup.c, but when the kernel booting, the console outputs mass characters. i think there must be something wrong about the serial setup. But where is it?
And if it can work i set the different cpu freq in boot an in kernel?
Thanks in advance!
Li


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