A.4
Other UNPREDICTABLE behaviors
This section describes other
UNPREDICTABLE
behaviors.
Table A-2 Other UNPREDICTABLE behaviors
Scenario
Description
CSSELR indicates a cache that
is not implemented.
If CSSELR indicates a cache that is not implemented, then on a read of the CCSIDR the behavior is
CONSTRAINED UNPREDICTABLE
, and can be one of the following:
•
The CCSIDR read is treated as
NOP
.
•
The CCSIDR read is
UNDEFINED
.
•
The CCSIDR read returns an
UNKNOWN
value (preferred).
HDCR.HPMN is set to 0, or to
a value larger than PMCR.N.
If HDCR.HPMN is set to 0, or to a value larger than PMCR.N, then the behavior in Non-secure EL0
and EL1 is
CONSTRAINED UNPREDICTABLE
, and one of the following must happen:
•
The number of counters accessible is an
UNKNOWN
non-zero value less than PMCR.N.
•
There is no access to any counters.
For reads of HDCR.HPMN by EL2 or higher, if this field is set to 0 or to a value larger than
PMCR.N, the core must return a
CONSTRAINED UNPREDICTABLE
value that is one of:
•
PMCR.N.
•
The value that was written to HDCR.HPMN.
•
(The value that was written to HDCR.HPMN) modulo 2h, where h is the smallest number of bits
required for a value in the range 0 to PMCR.N.
CRC32 or CRC32C instruction
with
size==64
.
On read of the instruction, the behavior is
CONSTRAINED UNPREDICTABLE
, and the instruction executes
with the additional decode:
size==32
.
CRC32 or CRC32C instruction
with
cond!=1110
in the A1
encoding.
The core implements the following option:
•
Executed unconditionally.
A Cortex
®
-A76 Core AArch32 unpredictable behaviors
A.4 Other UNPREDICTABLE behaviors
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Summary of Contents for Cortex-A76 Core
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