# $(2): (optional) pipe command to extract firmware, e.g. dd bs=n skip=m
default_do_upgrade() {
sync
+ echo 3 > /proc/sys/vm/drop_caches
if [ -n "$UPGRADE_BACKUP" ]; then
get_image "$1" "$2" | mtd $MTD_ARGS $MTD_CONFIG_ARGS -j "$UPGRADE_BACKUP" write - "${PART_NAME:-image}"
else