Table A-1 Armv8 Debug UNPREDICTABLE behaviors (continued)
Scenario Behavior
P ≥ M and P ≠31: reads and writes of PM
XEVTYPER_EL0 and PMXEVCNTR_EL0
The core implements:
• A simple implementation where all of SEL[4:0] are implemented, and if P ≥
M and P ≠31 then the register is RES0.
P ≥ M and P ≠31: value read in
PMSELR_EL0.SEL
The core implements:
• A simple implementation where all of SEL[4:0] are implemented, and if P ≥
M and P ≠31 then the register is RES0.
P = 31: reads and writes of PMXEVCNTR_EL0 The core implements:
• RES0.
n ≥ M: Direct access to PMEVCNTRn_EL0 and
PMEVTYPERn_EL0
The core implements:
• If n ≥ N, then the instruction is UNALLOCATED.
• Otherwise if n ≥ M, then the register is RES0.
Exiting Debug state while instruction issued
through EDITR is in flight
The core implements the following option:
• The instruction completes in Debug state before executing the restart.
Using memory-access mode with a non-word-
aligned address
The core behaves as indicated in the sole Preference:
• Does unaligned accesses, faulting if these are not permitted for the memory
type.
Access to memory-mapped registers mapped to
Normal memory
The core behaves as indicated in the sole Preference:
• The access is generated, and accesses might be repeated, gathered, split or
resized, in accordance with the rules for Normal memory, meaning the effect is
UNPREDICTABLE.
Not word-sized accesses or (AArch64 only)
doubleword-sized accesses
>
The core behaves as indicated in the sole Preference:
• Reads occur and return UNKNOWN data.
• Writes set the accessed register(s) to UNKNOWN.
External debug write to register that is being reset The core behaves as indicated in the sole Preference:
• Takes reset value.
A Cortex
®
-A76 Core AArch32 unpredictable behaviors
A.3 Armv8 Debug UNPREDICTABLE behaviors
100798_0300_00_en Copyright © 2016–2018 Arm Limited or its affiliates. All rights
reserved.
Appx-A-595
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