An incoming read or write request on a port is checked against each XMPU region as described in this section.
Tip: When a memory space is included in more than one XMPU region, the higher region number has higher priority (that is, region 0 has the lowest priority). This determines the set of permissions used for the checks described in this section.
For the enabled regions, two checks are done:
- The AXI_ADDR address is within the region: START_ADDR ≤ AXI_ADDR ≤ END_ADDR.
- The incoming AXI_SMID is allowed by the SMID_xx registers: AXI_SMID & [MASK] == [SMID] & [MASK].
If these checks are true, then the region configuration is checked with regards to security and read and write permissions.
Note: Disabled regions do not grant permissions.