Patent ID: 7991964

Claim:
An apparatus comprising: a pre-coherence channel; one or more cache agents coupled to the pre-coherence channel to communicate messages corresponding to cache operations including requests, writebacks, snoop data hit messages, snoop no data messages, and data acknowledgements; a protocol agent coupled to the pre-coherence channel to receive the messages, wherein the protocol agent is separated from the one or more cache agents, wherein at least one of a request followed by a writeback, the request followed by a snoop data hit message, and the request followed by a snoop no data message on the pre-coherence channel is re-ordered to avoid deadlock, wherein a data acknowledgment is capable to trigger a coherence protocol to enter a conflict phase, and wherein ordering at least one of a snoop data hit message followed by the data acknowledgement, and a snoop no data message followed by the data acknowledgement is communicated on the pre-coherence channel to ensure conflicts are properly detected.