1Feature Overview
2================
3
4This page provides an overview of the current |TF-A| feature set. For a full
5description of these features and their implementation details, please see
6the documents that are part of the *Components* and *System Design* chapters.
7
8The :ref:`Change Log & Release Notes` provides details of changes made since the
9last release.
10
11Current features
12----------------
13
14-  Initialization of the secure world, for example exception vectors, control
15   registers and interrupts for the platform.
16
17-  Library support for CPU specific reset and power down sequences. This
18   includes support for errata workarounds and the latest Arm DynamIQ CPUs.
19
20-  Drivers to enable standard initialization of Arm System IP, for example
21   Generic Interrupt Controller (GIC), Cache Coherent Interconnect (CCI),
22   Cache Coherent Network (CCN), Network Interconnect (NIC) and TrustZone
23   Controller (TZC).
24
25-  A generic |SCMI| driver to interface with conforming power controllers, for
26   example the Arm System Control Processor (SCP).
27
28-  SMC (Secure Monitor Call) handling, conforming to the `SMC Calling
29   Convention`_ using an EL3 runtime services framework.
30
31-  |PSCI| library support for CPU, cluster and system power management
32   use-cases.
33   This library is pre-integrated with the AArch64 EL3 Runtime Software, and
34   is also suitable for integration with other AArch32 EL3 Runtime Software,
35   for example an AArch32 Secure OS.
36
37-  A minimal AArch32 Secure Payload (*SP_MIN*) to demonstrate |PSCI| library
38   integration with AArch32 EL3 Runtime Software.
39
40-  Secure Monitor library code such as world switching, EL1 context management
41   and interrupt routing.
42   When a Secure-EL1 Payload (SP) is present, for example a Secure OS, the
43   AArch64 EL3 Runtime Software must be integrated with a Secure Payload
44   Dispatcher (SPD) component to customize the interaction with the SP.
45
46-  A Test SP and SPD to demonstrate AArch64 Secure Monitor functionality and SP
47   interaction with PSCI.
48
49-  SPDs for the `OP-TEE Secure OS`_, `NVIDIA Trusted Little Kernel`_
50   and `Trusty Secure OS`_.
51
52-  A Trusted Board Boot implementation, conforming to all mandatory TBBR
53   requirements. This includes image authentication, Firmware Update (or
54   recovery mode), and packaging of the various firmware images into a
55   Firmware Image Package (FIP).
56
57-  Pre-integration of TBB with the Arm CryptoCell product, to take advantage of
58   its hardware Root of Trust and crypto acceleration services.
59
60-  Reliability, Availability, and Serviceability (RAS) functionality, including
61
62   -  A Secure Partition Manager (SPM) to manage Secure Partitions in
63      Secure-EL0, which can be used to implement simple management and
64      security services.
65
66   -  An |SDEI| dispatcher to route interrupt-based |SDEI| events.
67
68   -  An Exception Handling Framework (EHF) that allows dispatching of EL3
69      interrupts to their registered handlers, to facilitate firmware-first
70      error handling.
71
72-  A dynamic configuration framework that enables each of the firmware images
73   to be configured at runtime if required by the platform. It also enables
74   loading of a hardware configuration (for example, a kernel device tree)
75   as part of the FIP, to be passed through the firmware stages.
76   This feature is now incorporated inside the firmware configuration framework
77   (fconf), which is still flagged as experimental.
78
79-  Support for alternative boot flows, for example to support platforms where
80   the EL3 Runtime Software is loaded using other firmware or a separate
81   secure system processor, or where a non-TF-A ROM expects BL2 to be loaded
82   at EL3.
83
84-  Support for the GCC, LLVM and Arm Compiler 6 toolchains.
85
86-  Support for combining several libraries into a "romlib" image that may be
87   shared across images to reduce memory footprint. The romlib image is stored
88   in ROM but is accessed through a jump-table that may be stored
89   in read-write memory, allowing for the library code to be patched.
90
91-  Support for the Secure Partition Manager Dispatcher (SPMD) component as a
92   new standard service.
93
94-  Support for ARMv8.3 pointer authentication in the normal and secure worlds.
95   The use of pointer authentication in the normal world is enabled whenever
96   architectural support is available, without the need for additional build
97   flags. Use of pointer authentication in the secure world remains an
98   experimental configuration at this time and requires the
99   ``BRANCH_PROTECTION`` option to be set to non-zero.
100
101-  Position-Independent Executable (PIE) support. Currently for BL2, BL31, and
102   TSP, with further support to be added in a future release.
103
104Still to come
105-------------
106
107-  Support for additional platforms.
108
109-  Refinements to Position Independent Executable (PIE) support.
110
111-  Continued support for the FF-A v1.0 (formally known as SPCI) specification, to enable the
112   use of secure partition management in the secure world.
113
114-  Documentation enhancements.
115
116-  Ongoing support for new architectural features, CPUs and System IP.
117
118-  Ongoing support for new Arm system architecture specifications.
119
120-  Ongoing security hardening, optimization and quality improvements.
121
122.. _SMC Calling Convention: https://developer.arm.com/docs/den0028/latest
123.. _OP-TEE Secure OS: https://github.com/OP-TEE/optee_os
124.. _NVIDIA Trusted Little Kernel: http://nv-tegra.nvidia.com/gitweb/?p=3rdparty/ote_partner/tlk.git;a=summary
125.. _Trusty Secure OS: https://source.android.com/security/trusty
126
127--------------
128
129*Copyright (c) 2019-2021, Arm Limited. All rights reserved.*
130