1Arm Development Platform Build Options
2======================================
3
4Arm Platform Build Options
5--------------------------
6
7-  ``ARM_BL31_IN_DRAM``: Boolean option to select loading of BL31 in TZC secured
8   DRAM. By default, BL31 is in the secure SRAM. Set this flag to 1 to load
9   BL31 in TZC secured DRAM. If TSP is present, then setting this option also
10   sets the TSP location to DRAM and ignores the ``ARM_TSP_RAM_LOCATION`` build
11   flag.
12
13-  ``ARM_CONFIG_CNTACR``: boolean option to unlock access to the ``CNTBase<N>``
14   frame registers by setting the ``CNTCTLBase.CNTACR<N>`` register bits. The
15   frame number ``<N>`` is defined by ``PLAT_ARM_NSTIMER_FRAME_ID``, which
16   should match the frame used by the Non-Secure image (normally the Linux
17   kernel). Default is true (access to the frame is allowed).
18
19-  ``ARM_FW_CONFIG_LOAD_ENABLE``: Boolean option to enable the loading of
20   FW_CONFIG device trees from the Firmware Image Package (FIP). When enabled,
21   BL2 calls the platform specific function `arm_bl2_el3_plat_config_load`.
22   This function is responsible for loading, parsing, and validating the
23   FW_CONFIG device trees from the FIP. The option depends on RESET_TO_BL2.
24
25-  ``ARM_DISABLE_TRUSTED_WDOG``: boolean option to disable the Trusted Watchdog.
26   By default, Arm platforms use a watchdog to trigger a system reset in case
27   an error is encountered during the boot process (for example, when an image
28   could not be loaded or authenticated). The watchdog is enabled in the early
29   platform setup hook at BL1 and disabled in the BL1 prepare exit hook. The
30   Trusted Watchdog may be disabled at build time for testing or development
31   purposes.
32
33-  ``ARM_LINUX_KERNEL_AS_BL33``: The Linux kernel expects registers x0-x3 to
34   have specific values at boot. This boolean option allows the Trusted Firmware
35   to have a Linux kernel image as BL33 by preparing the registers to these
36   values before jumping to BL33. This option defaults to 0 (disabled). For
37   AArch64 ``RESET_TO_BL31`` and for AArch32 ``RESET_TO_SP_MIN`` must be 1 when
38   using it. If this option is set to 1, ``ARM_PRELOADED_DTB_BASE`` must be set
39   to the location of a device tree blob (DTB) already loaded in memory. The
40   Linux Image address must be specified using the ``PRELOADED_BL33_BASE``
41   option.
42
43-  ``ARM_PLAT_MT``: This flag determines whether the Arm platform layer has to
44   cater for the multi-threading ``MT`` bit when accessing MPIDR. When this flag
45   is set, the functions which deal with MPIDR assume that the ``MT`` bit in
46   MPIDR is set and access the bit-fields in MPIDR accordingly. Default value of
47   this flag is 0. Note that this option is not used on FVP platforms.
48
49-  ``ARM_RECOM_STATE_ID_ENC``: The PSCI1.0 specification recommends an encoding
50   for the construction of composite state-ID in the power-state parameter.
51   The existing PSCI clients currently do not support this encoding of
52   State-ID yet. Hence this flag is used to configure whether to use the
53   recommended State-ID encoding or not. The default value of this flag is 0,
54   in which case the platform is configured to expect NULL in the State-ID
55   field of power-state parameter.
56
57-  ``ARM_ROTPK_LOCATION``: used when ``TRUSTED_BOARD_BOOT=1``. It specifies the
58   location of the ROTPK returned by the function ``plat_get_rotpk_info()``
59   for Arm platforms. Depending on the selected option, the proper private key
60   must be specified using the ``ROT_KEY`` option when building the Trusted
61   Firmware. This private key will be used by the certificate generation tool
62   to sign the BL2 and Trusted Key certificates. Available options for
63   ``ARM_ROTPK_LOCATION`` are:
64
65   -  ``regs`` : return the ROTPK hash stored in the Trusted root-key storage
66      registers.
67   -  ``devel_rsa`` : return a development public key hash embedded in the BL1
68      and BL2 binaries. This hash has been obtained from the RSA public key
69      ``arm_rotpk_rsa.der``, located in ``plat/arm/board/common/rotpk``. To use
70      this option, ``arm_rotprivk_rsa.pem`` must be specified as ``ROT_KEY``
71      when creating the certificates.
72   -  ``devel_ecdsa`` : return a development public key hash embedded in the BL1
73      and BL2 binaries. This hash has been obtained from the ECDSA public key
74      ``arm_rotpk_ecdsa.der``, located in ``plat/arm/board/common/rotpk``. To
75      use this option, ``arm_rotprivk_ecdsa.pem`` must be specified as
76      ``ROT_KEY`` when creating the certificates.
77   -  ``devel_full_dev_rsa_key`` : returns a development public key embedded in
78      the BL1 and BL2 binaries. This key has been obtained from the RSA public
79      key ``arm_rotpk_rsa.der``, located in ``plat/arm/board/common/rotpk``.
80
81-  ``ARM_ROTPK_HASH``: used when ``ARM_ROTPK_LOCATION=devel_*``, excluding
82   ``devel_full_dev_rsa_key``. Specifies the location of the ROTPK hash. Not
83   expected to be a build option. This defaults to
84   ``plat/arm/board/common/rotpk/*_sha256.bin`` depending on the specified
85   algorithm. Providing ``ROT_KEY`` enforces generation of the hash from the
86   ``ROT_KEY`` and overwrites the default hash file.
87
88-  ``ARM_TSP_RAM_LOCATION``: location of the TSP binary. Options:
89
90   -  ``tsram`` : Trusted SRAM (default option when TBB is not enabled)
91   -  ``tdram`` : Trusted DRAM (if available)
92   -  ``dram`` : Secure region in DRAM (default option when TBB is enabled,
93      configured by the TrustZone controller)
94
95-  ``ARM_XLAT_TABLES_LIB_V1``: boolean option to compile TF-A with version 1
96   of the translation tables library instead of version 2. It is set to 0 by
97   default, which selects version 2.
98
99-  ``ARM_GPT_SUPPORT``: Enable GPT parser to get the entry address and length of
100   the various partitions present in the GPT image. This support is available
101   only for the BL2 component, and it is disabled by default.
102   The following diagram shows the view of the FIP partition inside the GPT
103   image:
104
105   |FIP in a GPT image|
106
107For a better understanding of these options, the Arm development platform memory
108map is explained in the :ref:`Firmware Design`.
109
110.. _build_options_arm_css_platform:
111
112Arm CSS Platform-Specific Build Options
113---------------------------------------
114
115-  ``CSS_DETECT_PRE_1_7_0_SCP``: Boolean flag to detect SCP version
116   incompatibility. Version 1.7.0 of the SCP firmware made a non-backwards
117   compatible change to the MTL protocol, used for AP/SCP communication.
118   TF-A no longer supports earlier SCP versions. If this option is set to 1
119   then TF-A will detect if an earlier version is in use. Default is 1.
120
121-  ``CSS_LOAD_SCP_IMAGES``: Boolean flag, which when set, adds SCP_BL2 and
122   SCP_BL2U to the FIP and FWU_FIP respectively, and enables them to be loaded
123   during boot. Default is 1.
124
125-  ``CSS_USE_SCMI_SDS_DRIVER``: Boolean flag which selects SCMI/SDS drivers
126   instead of SCPI/BOM driver for communicating with the SCP during power
127   management operations and for SCP RAM Firmware transfer. If this option
128   is set to 1, then SCMI/SDS drivers will be used. Default is 0.
129
130- ``CSS_SYSTEM_GRACEFUL_RESET``: Build option to enable graceful powerdown of
131   CPU core on reset. This build option can be used on CSS platforms that
132   require all the CPUs to execute the CPU specific power down sequence to
133   complete a warm reboot sequence in which only the CPUs are power cycled.
134
135Arm FVP Build Options
136---------------------
137
138- ``FVP_TRUSTED_SRAM_SIZE``: Size (in kilobytes) of the Trusted SRAM region to
139  utilize when building for the FVP platform. This option defaults to 256.
140
141Arm Juno Build Options
142----------------------
143
144-  ``JUNO_AARCH32_EL3_RUNTIME``: This build flag enables you to execute EL3
145   runtime software in AArch32 mode, which is required to run AArch32 on Juno.
146   By default this flag is set to '0'. Enabling this flag builds BL1 and BL2 in
147   AArch64 and facilitates the loading of ``SP_MIN`` and BL33 as AArch32 executable
148   images.
149
150Arm Neoverse RD Platform Build Options
151--------------------------------------
152
153 - ``NRD_CHIP_COUNT``: Configures the number of chips on a Neoverse RD platform
154   which supports multi-chip operation. If ``NRD_CHIP_COUNT`` is set to any
155   valid value greater than 1, the platform code performs required configuration
156   to support multi-chip operation.
157
158- ``NRD_PLATFORM_VARIANT``: Selects the variant of a Neoverse RD platform. A
159  particular Neoverse RD platform may have multiple variants which may differ in
160  core count, cluster count or other peripherals. This build option is used to
161  select the appropriate platform variant for the build. The range of valid
162  values is platform specific.
163
164--------------
165
166.. |FIP in a GPT image| image:: ../../resources/diagrams/FIP_in_a_GPT_image.png
167
168*Copyright (c) 2019-2024, Arm Limited. All rights reserved.*
169