my poky tree:

/poky
  ---/meta-bebot
     ---/recipes-kernel
    	' --linux.bbapend
	'
	'---/linux
		'
		---defconfig


my debconfig file:

#changed for vivi driver on 31-10-2013, 1152hrs
CONFIG_VIDEO_VIVI=y

my linux.bbappend file:

FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
PRINC := "${@int(PRINC) + 1}"
SRC_URI += "file://defconfig"
CONFIG_VIDEO_VIVI=y