As per the CHI-B Spec Page number: 2-71:
The figure 2-24 shows the Streaming ordered WriteUnique transaction flow. It says that this flow prevents a read acquiring the new value of write-B before write-A is completed. Based on this diagram I have the below queries:
a) What data would be returned to the requester if the read is made to the same address that is used in the stream of writeunique txns before any of the CompAcks received?
b) What data would be returned to the requester if the read (Can be any read variant) is made to the same address that is used in the stream of writeunique txns after receiving the CompAck-A but before receiving the CompAck-B?
Before answering the above queries : please take into consideration the fact the Data is made visible only after receiving the corresponding compAck and also if you say that in the part (b) the data-A would be returned then how the coherency would be retained if the read also store the data in its cache after Comp-B is received.
Please let me know if I need to explain it bit more.
A read of location does not return the value of a write until all Requesters observe that write.