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Let's think about the case that a master issues a exclusive write transaction to a slave.
On the AXI Specifiaction document, it says that if the slave doesn't support "Exclusive Accesss", then it will always update the target.
But what about the response?
If the slave respond with "OKAY", the master may think that target is not updated. ("OKAY" is error response for the exclusive write transaction)
But, as slave doesn't support "Exclusive Access", it can not respond with "EXOKAY".
How can slave handle this case?
The protocol does not allow an exclusive write before or without an exclusive read, so it is not a case of "in most case", this just cannot legally happen.
So then all your questions are irrelevant, you won't have to consider them in a correctly designed system.
To answer your questions, the master doesn't know if the OKAY response to an isolated exclusive write indicates the target was updated or not.
But if the master had CORRECTLY attempted an exclusive read beforehand, it would then know if the slave supports exclusives or not, so there wouldn't be any issue as to whether a subsequent exclusive write updated the target.
Can I ask what you are trying to achieve with this illegal sequence that will cause problems ?
I'm just wondering why this document cares about the case that master send an Exclusive write to the slave which does not support Exclusive access.
As you said if exclusvice read always precedes exclusive write, this will never happen.
I think I'm confused because Exclusive Write is permitted to be issued for AHB protocol.
But it is illegal for AXI protocol. Right?
The AHB5 protocol allows an exclusive write without an exclusive read, but it immediately says that this exclusive write must fail and HEXOKAY must be deasserted, so it would be a pointless thing to do.
The AXI spec in this area then seems more sensible in making this an illegal thing to do if it must always fail.
So in AHB5 it is legal (but pointless), and in AXI it is illegal.