Cortex-A8 Technical Reference Manual - ARM Information Center

System Control Coprocessor
Table 3-79 shows how the bit values correspond with the PAR for an unsuccessful translation.
Bits Field Function
[31:7] - Reserved. UNP, SBZ.
Attempts to access the PAR in User mode results in an Undefined Instruction exception.
Note
The VA to PA translation can only generate an abort to the core if the operation failed because
an external abort occurred on the possible translation table request. In this case, the processor
does not update the PA Register. The processor updates the Data Fault Status Register and the
Fault Address Register:
• if the EA bit in the Secure Configuration Register is set to 1, the secure versions of the
two registers are updated and the processor traps the abort into Monitor mode
• if the EA bit in the Secure Configuration Register is not set to 1, the processor updates the
secure or nonsecure versions of the two registers, depends whether the core is in Secure
or Nonsecure state when the operation was issued.
For all other cases when the VA to PA operation fails, the processor only updates the PA
Register, secure or nonsecure version, depends whether the core is in Secure or Nonsecure state
when the operation was issued, with the Fault Status Register encoding and bit [0] set to 1. The
Data Fault Status Register and Fault Address Register remain unchanged and the processor does
not send an abort to the core.
To access the PA Register, read or write CP15 c7 with:
MRC p15, 0, , c7, c4, 0 ; Read PA Register
MCR p15, 0, , c7, c4, 0 ; Write PA Register
Table 3-79 PA Register for unsuccessful translation bit functions
[6:1] FSR[12,10,3:0] Holds the FSR bits for the aborted address. See c5, Data Fault Status Register on page 3-63
and c5, Auxiliary Fault Status Registers on page 3-66.
[0] - Indicates that the translation aborted:
1 = translation aborted.
VA to PA translation in the current Secure or Nonsecure state
The purpose of the VA to PA translation in the current Secure or Nonsecure state is to translate
the address with the current virtual mapping for either Secure or Nonsecure state.
The VA to PA translation in the current Secure or Nonsecure state use:
• CP15 c7
• four, write-only operations common to the Secure and Nonsecure states
• operations accessible in privileged modes only.
The operations work for privileged or User access permissions and returns information in the
PA Register for aborts, when the translation is unsuccessful, or translation table information,
when the translation succeeds.
Attempts to access the VA to PA translation operations in the current Secure or Nonsecure state
in User mode result in an Undefined Instruction exception.
To access the VA to PA translation in the current Secure or Nonsecure state, write CP15 c7 with:
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