What is the proper way of including linux kernel config?

I'm porting an old version of a software that is partly a linux kernel module to EL5, after doing the relevant hacks, the horrible GNU autotools mess that is used to compile the thing (no, it does not compile the kernel module via kbuild :( ) I keep getting lots of warnings 'Including config.h is deprecated' - I am told by google search results that I should be using -I flags instead, but cannot seem to find what flags and where I should put them.

The software is p开发者_开发问答roprietary, so can not link to it as it is not publicly available.

The version I am porting had support up to and including 2.6.16 (and I need 2.6.18-164 el5). The kernel space code is in the ballpark of 100k lines in dozens of files (and the compilation spans over a few Makefiles)

What is the proper way of fixing this?

Found it out eventually, I had to add "-include $LINUX_KERNEL_INCLUDE/linux/autoconf.h" to CPPFLAGS