Intel® Arria® 10 Hard Processor System Technical Reference Manual

ID 683711
Date 1/10/2023
Public

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10.3.15.4. AXI Master Configuration for ACP Access

To use the ACP for coherent accesses, the following configurations apply:

ACP master configurations must be as follows:
  • For coherent ACP read accesses, the AXI bits must be programmed as follows to avoid compromising coherency:
    • AxCACHE[3:0] attributes must match the properties defined in the Cortex-A9 MPCore MMU page tables for the relevant memory region.
    • Shareable attribute AxUSER[0] must be set to 0x1
The Cortex*-A9 MPCore* configuration for ACP use should be as follows:
  • The Snoop Control Unit must be enabled (by setting the SCU enable bit in the SCU Control Register at 0xFFFFC000).
  • Coherent memory must be marked cacheable and shareable.
  • The SMP bit of the ACTLR register must be set in the Cortex*-A9 processor that shares data over the ACP.
Note: To achieve maximum performance on the ACP, avoid switching from shared to non-shared requests and vice-versa. When a shared request is latched in the ACP and there are non-shared requests still pending, the non-shared requests must be completed before the shared request can proceed.

The following sections detail the attribute configurations necessary to support coherency.