1.7.1. About Cortex-A9 MPCore coherency

Memory coherency in a Cortex-A9 MPCore processor is maintained following a weakly ordered memory consistency model.

Cache coherency among L1 data caches of the Cortex-A9 processors in the cluster is maintained when the Cortex-A9 processors are operating in Symmetric Multi-Processing (SMP) mode. This mode is controlled by the SMP bit of the Auxiliary Control Register.

To be kept coherent, the memory must be marked as Write-Back, Shareable, Normal memory.

Note

When the Shareable attribute is applied to a memory region that is not Write-Back Normal memory, data held in this region is treated as Noncacheable.

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