undefined reference

[Anthony Chee]

The case is quite complicated.

I am now developing a module. This module need communicate with the kernel.
So I exported a function func(), by using EXPORT_SYMBOL(func). In the header
file, I set "extern int func()".

I also modified the kernel source code, which is inode.c, and insert the
func() and the module header file.

After the above procedure, I use "make bzImage" to build the kernel. At the
compile stage, it does not appear warning message, but it appears in the
linking object stage, which is

fs/fs.o(.text+0x1377d): undefined reference to `func'

How can I solve this issue? Or any parameter for "ld" to avoid checking the
undefined reference?
Thanks.