System Control
ARM DDI 0500D
Copyright © 2013-2014 ARM. All rights reserved.
4-41
ID021414
Non-Confidential
Table 4-49
shows the ID_AA64ISAR0_EL1 bit assignments.
To access the ID_AA64ISAR0_EL1:
MRS <Xt>, ID_AA64ISAR0_EL1 ; Read ID_AA64ISAR0_EL1 into Xt
Register access is encoded as follows:
4.3.21
AArch64 Memory Model Feature Register 0, EL1
The ID_AA64MMFR0_EL1 characteristics are:
Purpose
Provides information about the implemented memory model and memory
management support in the AArch64 Execution state.
Usage constraints
This register is accessible as follows:
Table 4-49 ID_AA64ISAR0_EL1 bit assignments
Bits
Name
Function
[63:20]
-
Reserved,
RES
0.
[19:16]
CRC32
0x1
CRC32 instructions are implemented.
[15:12]
SHA2
Indicates whether
SHA2
instructions are implemented. The possible values are:
0b0000
No
SHA2
instructions implemented. This is the value if the implementation does not include the
Cryptography Extension, or if it is disabled.
0b0001
SHA256H
,
SHA256H2
,
SHA256U0
, and
SHA256U1
implemented. This is the value if the implementation
includes the Cryptography Extension.
All other values reserved.
[11:8]
SHA1
Indicates whether
SHA1
instructions are implemented. The possible values are:
0b0000
No
SHA1
instructions implemented. This is the value if the implementation does not include the
Cryptography Extension.
0b0001
SHA1C
,
SHA1P
,
SHA1M
,
SHA1SU0
, and
SHA1SU1
implemented. This is the value if the implementation
includes the Cryptography Extension.
All other values reserved.
[7:4]
AES
Indicates whether
AES
instructions are implemented. The possible values are:
0b0000
No
AES
instructions implemented. This is the value if the implementation does not include the
Cryptography Extension.
0b0010
AESE
,
AESD
,
AESMC
, and
AESIMC
implemented, plus
PMULL
and
PMULL2
instructions operating on 64-bit
data. This is the value if the implementation includes the Cryptography Extension.
All other values reserved.
[3:0]
-
Reserved,
RES
0.
Table 4-50 ID_AA64ISAR0_EL1 access encoding
op0
op1
CRn
CRm
op2
11
000
0000
0110
000
EL0
EL1
(NS)
EL1
(S)
EL2
EL3
(SCR.NS = 1)
EL3
(SCR.NS = 0)
-
RO
RO
RO
RO
RO