Intel® Arria® 10 Hard Processor System Technical Reference Manual

ID 683711
Date 8/28/2023
Public
Document Table of Contents

10.3.15.2. AxPROT Attributes

AxPROT specifies the secure state of the transaction, and must match the security state of the target memory to ensure a cache hit; otherwise, it is a cache miss. ARPROT applies to read transactions, and AWPROT applies to write transactions.

The Cortex*-A9 MPU interprets ARPROT[1] and AWPROT[1] from ACP requests.

AxPROT[1] is used to protect against illegal transactions and to specify which address space is being accessed. This is important because in a Secure state, software can access both physical address spaces. The security of the access is not necessarily the same as the Security state of the processor that generated that access.

All ACP requests with AxPROT[0] identifies an access as unprivileged or privileged. When AxPROT[0] is set to 0, then access is 'Unprivileged'. When AxPROT[0] is set to 1, then access is 'Privileged'.

All ACP requests with AxPROT[2] indicates whether the transaction is a data access request or an instruction access. When AxPROT[2] is set to 0, then the request is a 'Data Access'. When AxPROT[2] is set to 1, then access is 'Instruction Access'.

The table below shows how the AxPROT[1] bit determines whether the access is secured or non-secured. When AxPROT[1] is set to 0, then the access is Secure. When AxPROT[1] is set to 1, then the access is Non-secure.

Table 91.  Protection Encoding
AxPROT Value Function
[0] 0 Unprivileged access
1 Privileged access
[1] 0 Secure access
1 Non-secure access
[2] 0 Data access
1 Instruction access