A data processing system (100, 600) has a memory hierarchy including a cache (124, 624) and a lower-level memory system (170, 650). A data element having a special write with inject attribute is received from a data producer (160, 640), such as an Ethernet controller. The data element is forwarded to the cache (124, 624) without accessing the lower-level memory system (170, 650). Subsequently at least one cache line containing the data element is updated in the cache (124, 624).