Table B-1 Armv8 Debug UNPREDICTABLE behaviors (continued)
Scenario
Behavior
Accessing reserved debug registers
The processor deviates from Preferred behavior because the hardware cost to decode
some of these addresses in debug power domain is significantly high:
Actual behavior:
1. For reserved debug and Performance Monitors registers the response is
CONSTRAINED UNPREDICTABLE
Error or
RES0
, when any of the following
error instead of preferred
RES0
for reserved debug registers
0x000
-
0xCFC
and reserved PMU registers
0x000
-
0xF00
:
Off
Core power domain is either completely off, or in a low-power
state where the Core power domain registers cannot be
accessed.
DLK
DoubleLockStatus()
is TRUE, OS double-lock is locked,
that is, EDPRSR.DLK is 1.
OSLK
OSLSR_EL1.OSLK is1, OS lock is locked.
2. In addition, for reserved debug registers in the address ranges
0x400
to
0x4FC
and
0x800
to
0x8FC
, the response is
CONSTRAINED
UNPREDICTABLE
Error or
RES0
EDAD
AllowExternalDebugAccess()
is FALSE, external debug
access is disabled.
3. For reserved Performance Monitor registers in the address ranges
0x000
to
0x0FC
and
0x400
to
0x47C
, the response is
CONSTRAINED
UNPREDICTABLE
Error, or
RES0
apply, and the following errors instead of preferred res0 for the these
registers:
EPMAD
AllowExternalPMUAccess()
is FALSE (external
Performance Monitors access is disabled).
Clearing the
clear-after-read
EDPRSR bits
when Core power domain is on, and
DoubleLockStatus()
is TRUE
The processor behaves as indicated in the sole Preference:
•
Bits are not cleared to zero.
B AArch32 UNPREDICTABLE Behaviors
B.4 Armv8 Debug UNPREDICTABLE behaviors
100236_0100_00_en
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Summary of Contents for Cortex-A35
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