How to make the kernel support NTFS?

[Parmenides]

The problem has been resolved by recovering an old .config file, which
once was deleted with the old kernel. I think this problem has not to
do with 'NTFS' options anywhere, but improper configrations of kernel.
The steps are as follows:

step 1. Copy the old .config to /boot/config-2.6.34. This .config is
from the old 2.6.25 kernel source directory.
step 2. Enter the new 2.6.34 kernel source directory, then 'make clean
&& make mrproper' to clean the directory.
step 3. 'make menuconfig' to select NTFS options.
step 4. 'make && make modules_install', then copy
arch/x86/boot/bzImage to /boot and modify /boot/grub/menu.lst.
step 5. Reboot successfully.

However, I have a further questions about the old .config file. At
step 1, I didn't copy the old .config into the new 2.6.34 kernel
source directory, and then 'make oldconfig' to activate old
configurations. The only place where the old .config exists is /boot.
At step 3, how can 'make' find the old .config file?