Copyright © 2013-2022 Arm Limited or its affiliates. All rights reserved.
ARM DDI 0487I.a (ID081822)
Arm
®
Architecture Reference Manual
for A-profile architecture
ii Copyright © 2013-2022 Arm Limited or its affiliates. All rights reserved. ARM DDI 0487I.a
Non-Confidential ID081822
Arm Architecture Reference Manual
Copyright © 2013-2022 Arm Limited or its affiliates. All rights reserved.
Release Information
The following releases of this document have been made.
Release history
Date Issue Confidentiality Change
30 April 2013 A.a-1 Confidential-Beta Draft Beta draft of first issue, limited circulation
12 June 2013 A.a-2 Confidential-Beta Draft Second beta draft of first issue, limited circulation
04 September 2013 A.a Non-Confidential Beta Beta release
24 December 2013 A.b Non-Confidential Beta Second beta release
18 July 2014 A.c Non-Confidential Beta Third beta release
09 October 2014 A.d Non-Confidential Beta Fourth beta release
17 December 2014 A.e Non-Confidential Beta Fifth beta release
25 March 2015 A.f Non-Confidential Beta Sixth beta release
10 July 2015 A.g Non-Confidential Beta Seventh beta release
30 September 2015 A.h Non-Confidential Beta Eighth beta release
28 January 2016 A.i Non-Confidential Beta Ninth beta release
03 June 2016 A.j Non-Confidential EAC EAC release
30 September 2016 A.k Non-Confidential Armv8.0 EAC Updated EAC release
31 March 2017 B.a Non-Confidential Armv8.1 EAC, v8.2 Beta Initial release incorporating Armv8.1 and Armv8.2
26 September 2017 B.b Non-Confidential Armv8.2 EAC Initial Armv8.2 EAC release, incorporating SPE
20 December 2017 C.a Non-Confidential Armv8.3 EAC Initial Armv8.3 EAC release
31 October 2018 D.a Non-Confidential Armv8.4 EAC Initial Armv8.4 EAC release
29 April 2019 D.b Non-Confidential Armv8.4 EAC Updated Armv8.4 EAC release incorporating accessibility changes
05 July 2019 E.a Non-Confidential Armv8.5 EAC Initial Armv8.5 EAC release
20 February 2020 F.a Non-Confidential Armv8.6 Beta Initial Armv8.6 Beta release
31 March 2020 F.b Non-Confidential Armv8.5 EAC, v8.6 Beta Armv8.5 EAC release, initial Armv8.6 Beta release
17 July 2020 F.c Non-Confidential Armv8.6 EAC Initial Armv8.6 EAC release
22 January 2021 G.a Non-Confidential Armv8.7 EAC Initial Armv8.7 EAC release
22 July 2021 G.b Non-Confidential Armv8.7 EAC Updated Armv8.7 EAC release
04 February 2022 H.a Non-Confidential Armv9 EAC Initial Armv9 EAC release
19 August 2022 I.a Non-Confidential Armv9 EAC release Updated Armv9 EAC release incorporating BRBE, ETE, and TRBE
ARM DDI 0487I.a Copyright © 2013-2022 Arm Limited or its affiliates. All rights reserved. iii
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iv Copyright © 2013-2022 Arm Limited or its affiliates. All rights reserved. ARM DDI 0487I.a
Non-Confidential ID081822
Limitations of this issue
This issue of the Arm Architecture Reference Manual contains many improvements and corrections. Validation of this document
has identified the following issues that Arm will address in future issues:
• Some diagrams in the register descriptions chapter have long field names that split over several lines. These are not wrong,
and the descriptions list the field name correctly.
•The Performance Monitors external register descriptions on page I5-10753 do not include updates to registers or fields
that change as a result of the optional 64-bit external access feature.
• Appendix K16 Arm Pseudocode Definition requires further review and update. Since this appendix is informative, rather
than being part of the architecture specification, this does not affect the quality status of this release.
• For a list of the known issues in this Manual, please refer to the Known Issues document on
https://developer.arm.com/documentation/102105/latest
.
• For a list of the known issues in the System register and instruction XML content, please refer to the Release Notes on
https://developer.arm.com/architectures/cpu-architecture/a-profile/exploration-tools
.
ARM DDI 0487I.a Copyright © 2013-2022 Arm Limited or its affiliates. All rights reserved. v
ID081822 Non-Confidential
Contents
Arm Architecture Reference Manual for A-profile
architecture
Preface
About this Manual ................................................................................................... xviii
Using this Manual ...................................................................................................... xx
Conventions ........................................................................................................... xxvii
Additional reading .................................................................................................... xxx
Feedback ............................................................................................................... xxxii
Part A Arm Architecture Introduction and Overview
Chapter A1 Introduction to the Arm Architecture
A1.1 About the Arm architecture ................................................................................. A1-36
A1.2 Architecture profiles ............................................................................................ A1-38
A1.3 Arm architectural concepts .................................................................................. A1-39
A1.4 Supported data types .......................................................................................... A1-42
A1.5 Floating-point support ......................................................................................... A1-55
A1.6 The Arm memory model ...................................................................................... A1-69
Chapter A2 Armv8-A Architecture Extensions
A2.1 Armv8.0 architecture extensions ......................................................................... A2-72
A2.2 Architectural features within Armv8.0 architecture .............................................. A2-76
A2.3 The Armv8 Cryptographic Extension ................................................................... A2-80
A2.4 The Armv8.1 architecture extension .................................................................... A2-82
A2.5 The Armv8.2 architecture extension .................................................................... A2-86
A2.6 The Armv8.3 architecture extension .................................................................... A2-96
A2.7 The Armv8.4 architecture extension .................................................................. A2-101
A2.8 The Armv8.5 architecture extension .................................................................. A2-107
