Each XMPU has 16 regions, numbered from 0 to 15. Each region is defined by a start address and an end address. There are two region address alignment types. The 4 KB granularity is used for all XMPUs except the one in the DDRMC.
When a memory space is included in more than one XMPU region configuration, the higher region number has higher priority (that is, region 0 has lowest priority). Each region can be independently enabled or disabled. If a region is disabled, it does not include protection checking.
If none of the regions are enabled or the request does not match any of the regions, then a subtractive decode determines whether or not the request is allowed. That is, the XMPU takes the default action as specified in the XMPU control register.