A cache coherent data processing system includes at least first and second
coherency domains. In a first cache memory within the first coherency
domain of the data processing system, a coherency state field associated
with a storage location and an address tag is set to a first data-invalid
coherency state that indicates that the address tag is valid and that the
storage location does not contain valid data. In response to snooping an
exclusive access operation, the exclusive access request specifying a
target address matching the address tag and indicating a relative domain
location of a requester that initiated the exclusive access operation,
the first cache memory updates the coherency state field from the first
data-invalid coherency state to a second data-invalid coherency state
that indicates that the address tag is valid, that the storage location
does not contain valid data, and whether a target memory block associated
with the address tag is cached within the first coherency domain upon
successful completion of the exclusive access operation based upon the
relative location of the requestor.