Intel® Arria® 10 Hard Processor System Technical Reference Manual

ID 683711
Date 1/10/2023
Public

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10.4.1.3. L2 Cache Parity

Because the L2 data RAM is ECC-protected, parity checking on the data RAM is not required. However, because the tag RAM is not ECC protected, it requires parity checking. Because parity cannot be configured independently, parity checking for both the data RAM and tag RAM must be enabled.

Ideally, parity should be enabled before the L2 cache is enabled. If the cache is already enabled, you must clean the cache and disable it before parity is enabled. After enabling parity, the cache is invalidated and enabled. To enable parity:

  1. Set the Parity_on bit in the L2 Auxiliary Control register.
  2. Invalidate the L2 cache through the Cache Maintenance Operations registers.
  3. Enable the cache through the L2_Cache_enable bit of the L2 Control register.
Note: If you would like the parity errors to be reported you must enable the parity interrupts in the L2 Interrupt Mask register along with the corresponding interrupts in the general interrupt controller (GIC).

Refer to the Arm* Infocenter website for more information regarding L2 cache registers and programming.

Parity Error Handling

If a parity error occurs in the tag or data RAM during AXI read transactions, a SLVERR response is reported through the event bus and interrupt signals. If a parity error occurs on tag or data RAM during AXI write transactions, a SLVERR response is reported back through a SLVERRINTR interrupt signal. For cache maintenance operations, if a parity error occurs on tag or data RAM, the error is reported back through the interrupt lines only. In addition, the L2 Cache cannot refill a line from external memory due to a parity error.