B1.39
Cache Size ID Register
The CCSIDR characteristics are:
Purpose
Provides information about the architecture of the caches.
Usage constraints
This register is accessible as follows:
EL0
(NS)
EL0
(S)
EL1
(NS)
EL1
(S)
EL2 EL3
(SCR.NS = 1)
EL3
(SCR.NS = 0)
-
-
RO
RO
RO
RO
RO
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).
Configurations
CCSIDR is architecturally mapped to AArch64 register CCSIDR_EL1. See
.
There is one copy of this register that is used in both Secure and Non-secure states.
The implementation includes one CCSIDR for each cache that it can access. CSSELR selects
which Cache Size ID Register is accessible.
Attributes
CCSIDR is a 32-bit register.
WB
31
28 27
12
3
0
RA
LineSize
WT
30 29
13
2
WA
NumSets
Associativity
Figure B1-3 CCSIDR bit assignments
WT, [31]
Indicates support for Write-Through:
0
Cache level does not support Write-Through.
WB, [30]
Indicates support for Write-Back:
0
Cache level does not support Write-Back.
1
Cache level supports Write-Back.
RA, [29]
Indicates support for Read-Allocation:
0
Cache level does not support Read-Allocation.
1
Cache level supports Read-Allocation.
B1 AArch32 system registers
B1.39 Cache Size ID Register
100236_0100_00_en
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B1-201
Non-Confidential
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