Intel® Quartus® Prime Pro Edition User Guide: Platform Designer

ID 683609
Date 10/04/2021
Public

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1.9.3. Accessing Undefined Memory Regions

Access to an undefined memory region occurs when a transaction from a master targets a memory region unspecified in the slave memory map. To ensure predictable response behavior when this condition occurs, you must specify a default slave, as Specifying a Default Slave describes.

You can designate any memory-mapped slave as a default slave. Have only one default slave for each interconnect domain in your system. Platform Designer then routes undefined memory region accesses to the default slave, which terminates the transaction with an error response.

Note:

If you do not specify the default slave, Platform Designer automatically assigns the slave at the lowest address within the memory map for the master that issues the request as the default slave.

Accessing undefined memory regions can occur in the following cases:

  • When there are gaps within the accessible memory map region that are within the addressable range of slaves, but are not mapped.
  • Accesses by a master to a region that does not belong to any slaves that is mapped to the master.
  • When a non-secured transaction is accessing a secured slave. This applies to only slaves that are secured at compilation time.
  • When a read-only slave is accessed with a write command, or a write-only slave is accessed with a read command.