kernel compile error and some questions

Dear group,

I'm a student doing an internship. My task is to port linux to a custom
made powerpc(405)board. After reading a lot about embedded linux (also
this group), i'm really trying to compile the kernel. As root i want to
use the initramfs (the board has to be up in 4sec), the bootloader is
already in place (u-boot)from the normal (selfmade)OS running the
board. I builded a selfmade crossgcc and one from the buildroot project
(how can i verify that they really work?).

When compiling the kernel i have some questions:
*Do i have to set the memory map in the .config file?
(CONFIG_KERNEL_START...)?
*And what does the board option do (walnut, oak, ...) can't seem to
find any information what to do with a custom board.

When compiling the kernel i get the following errors (using the
buildroot gcc):
...
LD init/built-in.o
LD .tmp_vmlinux1
drivers/built-in.o: In function `init_one_smi':
ipmi_si_intf.c:(.text+0x26de0): undefined reference to
`is_new_interface'
ipmi_si_intf.c:(.text+0x26f10): undefined reference to
`is_new_interface'
drivers/built-in.o: In function `wbsd_release_resources':
wbsd.c:(.text+0x5fef8): undefined reference to `free_dma'
drivers/built-in.o: In function `wbsd_probe':
wbsd.c:(.text+0x60480): undefined reference to `request_dma'
wbsd.c:(.text+0x60508): undefined reference to `free_dma'
make: *** [.tmp_vmlinux1] Fout 1

my command was:

make vmlinux ARCH=ppc CROSS_COMPILE=powerpc-linux-

(vmlinux because it is a very stripped version of u-boot that cannot
load compressed kernels)
Is this a fault in my coonfiguration or in my gcc?

Thanks,
Joachim Denil
Student Karel de Grote Hogeschool Antwerpen - Belgium