#### Defined in the .inc
# Set a variable in .configure
# $1 - Configure variable to be set
# $2 - value [n/y/value]
kernel_configure_variable() {
    # Remove the config
    CONF_SED_SCRIPT="$CONF_SED_SCRIPT /CONFIG_$1[ =]/d;"
    if test "$2" = "n"
    then
        echo "# CONFIG_$1 is not set" >> ${B}/.config
    else
        echo "CONFIG_$1=$2" >> ${B}/.config
    fi
}

#### In my .bbappend:
kernel_configure_variable "RD_GZIP" "y"

#### Error:
ERROR: ParseError at FILE_PATH:3: unparsed line: 'kernel_configure_variable "BLK_DEV_INITRD" "y"'