Kernel debug about Linux for PowerPC

Hello,

I want to use the gdb to debug the kernel version 2.2.13 for my MPC860
board.
So I set the compiler configuration parameter CONFIG_KGDB = YES,
but when I re-compile the kernel, it complains that

arch/ppc/kernel/kernel.o(.text+0x68ac): undefined reference to
`getDebugChar'
arch/ppc/kernel/kernel.o(.text+0x6934): undefined reference to
`putDebugChar'

PROBLEM:
what's wrong? I find no define for function "getDebugChar" in arch/ppc
directory.

Any suggestion is appreciated!

BRs,
Shuangjun


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