5.8.3. TCM arbitration

The TCU contains arbitration logic to arbitrate between TCM access requests for the LSU, PFU, AHBS and SQ. In most cases, the LSU has the highest priority, followed by the PFU, AHBs, and the SQ having the lowest priority.

When a higher-priority requestor is accessing a TCM, an access from a lower-priority device stalls.

In some circumstances the SQ can have the highest priority temporarily, for example, when a RAW hazard occurs because of a load from the same address as a store in the SQ. This ensures that the hazard is cleared as quickly as possible allowing the load to proceed. The AHBS interface might have the highest priority because of AHBS priority boosting, see AHBS interface arbitration. If the SQ and AHBS are priority boosted at the same time, the SQ then has the highest priority.

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