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Should slaves/bridges which have some form of write buffer capability also include forwarding logic to return the result of a read transaction when a write to the same location is stored in the write buffer?

Applies to: AXI

Answer

Slaves/bridges may need additional logic if they are going to provide an early write response (before the write is fully completed). The minimum that it needs is hazard detection, which detects a read to an address that is stored within the write buffer.

If a read-after-write hazard is detected then the slave/bridge can either stall the read operation until the write has fully completed, or implement forwarding logic to provide the correct read data prior to the write fully completing.

The above complexity is avoided if a slave only provides a write response when the write has fully completed.

Article last edited on: 2008-09-09 15:47:45

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