The AMD memory protection unit (XMPU) verifies that a transaction is explicitly allowed to access a memory address. The XMPU is a region-based memory protection unit. This section describes the XMPU in detail, including configuration and functionality.
System protection is applied to incoming AXI transaction requests. The transaction is checked for:
- System management identification (SMID)
- TrustZone secure or non-secure (NS)
- Read or write access type
XMPUs are associated with the interconnect. Examples include:
- PMC_XMPU on IOP flash and CFU
- OCM_XMPU for the OCM memory
- FPD_XMPU on destinations
- DDR memory controllers
Use Case Example
In this system protection use case, the RPU runs a safety application where a certain region of the OCM might be required to be protected and dedicated for use by the RPU. To accomplish these requirements, the following are required:
- RPU generates secure transactions
- An XMPU can protect a region of the OCM for exclusive use by the RPU and makes the rest of memory available for use by allowed others