How to understand Device-nGRE?

Hello,

The three device attributes are G, R, and E, with the following definitions:

• Gathering (G/nG)
  - Determines whether multiple accesses can be merged into a single bus transaction
  - nG: Number/size of accesses on the bus = number/size of accesses in code

• Reordering (R/nR)
  - Determines whether accesses to the same device can be reordered
  - nR: Accesses to the same IMPLEMENTATION DEFINED block size will appear on the bus in program order

• Early Write Acknowledgement (E/nE)
  - Indicates to the memory system whether a buffer can send acknowledgements
  - nE: The response should come from the end slave, not buffering in the interconnect

So with the above said:

• Device-nGRE is device memory where Reordering and Early Write Acknowledgements are allowed, but multiple accesses cannot be merged into a single bus transaction

• Device-nGnRE is device memory where Early Write Acknowledgements are allowed, but multiple accesses cannot be merged into a single bus transaction, and accesses to the same IMPLEMENTATION DEFINED block size will appear on the bus in program order

I hope that helps,

Ash.