adding preprocessor defines in module makefiles

[Christopher Harvey]

Hi,

I'm trying to build a kernel module for fun, and I can't figure out a 
clean way to add preprocessor defines that correspond to Kconfig values. 
I'm trying to set CONFIG_SND_DEBUG specifically. My module has only one 
file, and I've tried adding #define CONFIG_SND_DEBUG as the first line 
in the .c file, but now I'm getting the following warning:
WARNING: "__snd_printk" [/home/chris/snd/snd-foo.ko] undefined!

I haven't compiled the kernel running on my system with the 
CONFIG_SND_DEBUG option but I haven't been able to see a reason why that 
should change anything for my module.

thanks,
Chris