The OCM memory is protected by the OCM_XMPU protection unit using SMID, TrustZone status, and address ranges that are configured as read and/or write.
The XMPU defines 16 address regions where each region is configured for read or write protection for a set of SMIDs, and it can be configured as a secure or non-secure TrustZone region. The base address and upper address for each region is defined with a 4 KB granularity.
If a write, SMID, or TrustZone violation occurs, the XMPU returns an APB bus error signal back to the interconnect. Valid data is not returned to the source on a read operation and no data is written to the OCM on a write operation.