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IFSR has a specific format when using the Long-descriptor translation table format.
The following figure shows the IFSR bit assignments when using the Long-descriptor translation table format.
External abort type. This field indicates whether an AXI Decode or Slave error caused an abort:
|External abort marked as DECERR.|
|External abort marked as SLVERR.|
For aborts other than external aborts this bit always returns 0.
Fault Status bits. This field indicates the type of exception generated. Any encoding not listed is reserved.
|Address size fault in TTBR0 or TTBR1.|
|Translation fault, LL bits indicate level.|
|Access fault flag, LL bits indicate level.|
|Permission fault, LL bits indicate level.|
|Synchronous external abort.|
|Synchronous external abort on translation table walk, LL bits indicate level.|
|Synchronous parity error on memory access.|
|Synchronous parity error on memory access on translation table walk, LL bits indicate level.|
|TLB conflict abort.|
Table B1-69 Encodings of LL bits associated with the MMU fault
If a Data Abort exception is generated by an instruction cache maintenance operation when the Long-descriptor translation table format is selected, the fault is reported as a Cache Maintenance fault in the DFSR or HSR with the appropriate Fault Status code. For such exceptions reported in the DFSR, the corresponding IFSR is unknown.
To access the IFSR:
MRC p15, 0, <Rt>, c5, c0, 1; Read IFSR into Rt MCR p15, 0, <Rt>, c5, c0, 1; Write Rt to IFSR
Register access is encoded as follows:
Table B1-70 IFSR access encoding