[Buildroot] Building debug version of kernel

Is editing the top-level Linux Makefile the standard method for my host
machine to build a debug version (i.e. with "-g -O0" CFLAGS) of the Linux
2.6 kernel?  If so, should I make these flag changes to CFLAGS_KERNEL or
HOSTCFLAGS or both?

The build output only shows the format "CC <object-file-name>" without
flags, so I can't see what it's actually doing.

Best Regards,
Jerry