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ARM DDI 0301H
ID012310
External abort on data read/write
Externally generated errors during a data read or write can be imprecise. This means that
R14_abt on entry into the abort handler on such an abort might not hold an address that is related
to the instruction that caused the exception. Correspondingly, external aborts can be
unrecoverable. See Aborts on page 2-45 for more details.
The Fault Address Register is updated with an invalid value, all zeros, on an imprecise external
abort on a data access.
In case a precise external abort occurs during a multiple load or store operation, the FAR in the
appropriate world is always updated with the base address of an AXI burst.
External abort on VA to PA translation operation
For VA to PA translation operations, the only case when an external abort can be asserted is
during the page table walk.
In this case, the external abort is precise, and both the DFSR and the FAR are updated in the
world, Secure or Non-secure, that generated the VA to PA translation operation. This is in
addition to the standard abort mechanism occurring during VA to PA translation operations, that
update the PA register of the corresponding world with the appropriate FSR encoding.
External abort on a hardware page table walk
An external abort occurring on a hardware page table access must be returned with the page
table data. Such aborts are precise. The FAR is updated on an external abort on a hardware page
table walk on a data access, and the IFAR is updated on an external abort on a hardware page
table walk on an instruction access. The appropriate Fault Status Register indicates that this has
occurred.
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Memory Management Unit
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