xref: /rk3399_ARM-atf/docs/getting_started/build-options.rst (revision dc78e62d80e64bf4fe5d5bf4844a7bd1696b7c92)
1Build Options
2=============
3
4The TF-A build system supports the following build options. Unless mentioned
5otherwise, these options are expected to be specified at the build command
6line and are not to be modified in any component makefiles. Note that the
7build system doesn't track dependency for build options. Therefore, if any of
8the build options are changed from a previous build, a clean build must be
9performed.
10
11.. _build_options_common:
12
13Common build options
14--------------------
15
16-  ``AARCH32_INSTRUCTION_SET``: Choose the AArch32 instruction set that the
17   compiler should use. Valid values are T32 and A32. It defaults to T32 due to
18   code having a smaller resulting size.
19
20-  ``AARCH32_SP`` : Choose the AArch32 Secure Payload component to be built as
21   as the BL32 image when ``ARCH=aarch32``. The value should be the path to the
22   directory containing the SP source, relative to the ``bl32/``; the directory
23   is expected to contain a makefile called ``<aarch32_sp-value>.mk``.
24
25-  ``AMU_RESTRICT_COUNTERS``: Register reads to the group 1 counters will return
26   zero at all but the highest implemented exception level.  Reads from the
27   memory mapped view are unaffected by this control.
28
29-  ``ARCH`` : Choose the target build architecture for TF-A. It can take either
30   ``aarch64`` or ``aarch32`` as values. By default, it is defined to
31   ``aarch64``.
32
33-  ``ARM_ARCH_FEATURE``: Optional Arm Architecture build option which specifies
34   one or more feature modifiers. This option has the form ``[no]feature+...``
35   and defaults to ``none``. It translates into compiler option
36   ``-march=armvX[.Y]-a+[no]feature+...``. See compiler's documentation for the
37   list of supported feature modifiers.
38
39-  ``ARM_ARCH_MAJOR``: The major version of Arm Architecture to target when
40   compiling TF-A. Its value must be numeric, and defaults to 8 . See also,
41   *Armv8 Architecture Extensions* and *Armv7 Architecture Extensions* in
42   :ref:`Firmware Design`.
43
44-  ``ARM_ARCH_MINOR``: The minor version of Arm Architecture to target when
45   compiling TF-A. Its value must be a numeric, and defaults to 0. See also,
46   *Armv8 Architecture Extensions* in :ref:`Firmware Design`.
47
48-  ``BL2``: This is an optional build option which specifies the path to BL2
49   image for the ``fip`` target. In this case, the BL2 in the TF-A will not be
50   built.
51
52-  ``BL2U``: This is an optional build option which specifies the path to
53   BL2U image. In this case, the BL2U in TF-A will not be built.
54
55-  ``BL2_AT_EL3``: This is an optional build option that enables the use of
56   BL2 at EL3 execution level.
57
58-  ``BL2_ENABLE_SP_LOAD``: Boolean option to enable loading SP packages from the
59   FIP. Automatically enabled if ``SP_LAYOUT_FILE`` is provided.
60
61-  ``BL2_IN_XIP_MEM``: In some use-cases BL2 will be stored in eXecute In Place
62   (XIP) memory, like BL1. In these use-cases, it is necessary to initialize
63   the RW sections in RAM, while leaving the RO sections in place. This option
64   enable this use-case. For now, this option is only supported when BL2_AT_EL3
65   is set to '1'.
66
67-  ``BL31``: This is an optional build option which specifies the path to
68   BL31 image for the ``fip`` target. In this case, the BL31 in TF-A will not
69   be built.
70
71-  ``BL31_KEY``: This option is used when ``GENERATE_COT=1``. It specifies the
72   file that contains the BL31 private key in PEM format. If ``SAVE_KEYS=1``,
73   this file name will be used to save the key.
74
75-  ``BL32``: This is an optional build option which specifies the path to
76   BL32 image for the ``fip`` target. In this case, the BL32 in TF-A will not
77   be built.
78
79-  ``BL32_EXTRA1``: This is an optional build option which specifies the path to
80   Trusted OS Extra1 image for the  ``fip`` target.
81
82-  ``BL32_EXTRA2``: This is an optional build option which specifies the path to
83   Trusted OS Extra2 image for the ``fip`` target.
84
85-  ``BL32_KEY``: This option is used when ``GENERATE_COT=1``. It specifies the
86   file that contains the BL32 private key in PEM format. If ``SAVE_KEYS=1``,
87   this file name will be used to save the key.
88
89-  ``BL33``: Path to BL33 image in the host file system. This is mandatory for
90   ``fip`` target in case TF-A BL2 is used.
91
92-  ``BL33_KEY``: This option is used when ``GENERATE_COT=1``. It specifies the
93   file that contains the BL33 private key in PEM format. If ``SAVE_KEYS=1``,
94   this file name will be used to save the key.
95
96-  ``BRANCH_PROTECTION``: Numeric value to enable ARMv8.3 Pointer Authentication
97   and ARMv8.5 Branch Target Identification support for TF-A BL images themselves.
98   If enabled, it is needed to use a compiler that supports the option
99   ``-mbranch-protection``. Selects the branch protection features to use:
100-  0: Default value turns off all types of branch protection
101-  1: Enables all types of branch protection features
102-  2: Return address signing to its standard level
103-  3: Extend the signing to include leaf functions
104-  4: Turn on branch target identification mechanism
105
106   The table below summarizes ``BRANCH_PROTECTION`` values, GCC compilation options
107   and resulting PAuth/BTI features.
108
109   +-------+--------------+-------+-----+
110   | Value |  GCC option  | PAuth | BTI |
111   +=======+==============+=======+=====+
112   |   0   |     none     |   N   |  N  |
113   +-------+--------------+-------+-----+
114   |   1   |   standard   |   Y   |  Y  |
115   +-------+--------------+-------+-----+
116   |   2   |   pac-ret    |   Y   |  N  |
117   +-------+--------------+-------+-----+
118   |   3   | pac-ret+leaf |   Y   |  N  |
119   +-------+--------------+-------+-----+
120   |   4   |     bti      |   N   |  Y  |
121   +-------+--------------+-------+-----+
122
123   This option defaults to 0.
124   Note that Pointer Authentication is enabled for Non-secure world
125   irrespective of the value of this option if the CPU supports it.
126
127-  ``BUILD_MESSAGE_TIMESTAMP``: String used to identify the time and date of the
128   compilation of each build. It must be set to a C string (including quotes
129   where applicable). Defaults to a string that contains the time and date of
130   the compilation.
131
132-  ``BUILD_STRING``: Input string for VERSION_STRING, which allows the TF-A
133   build to be uniquely identified. Defaults to the current git commit id.
134
135-  ``BUILD_BASE``: Output directory for the build. Defaults to ``./build``
136
137-  ``CFLAGS``: Extra user options appended on the compiler's command line in
138   addition to the options set by the build system.
139
140-  ``COLD_BOOT_SINGLE_CPU``: This option indicates whether the platform may
141   release several CPUs out of reset. It can take either 0 (several CPUs may be
142   brought up) or 1 (only one CPU will ever be brought up during cold reset).
143   Default is 0. If the platform always brings up a single CPU, there is no
144   need to distinguish between primary and secondary CPUs and the boot path can
145   be optimised. The ``plat_is_my_cpu_primary()`` and
146   ``plat_secondary_cold_boot_setup()`` platform porting interfaces do not need
147   to be implemented in this case.
148
149-  ``COT``: When Trusted Boot is enabled, selects the desired chain of trust.
150   Defaults to ``tbbr``.
151
152-  ``CRASH_REPORTING``: A non-zero value enables a console dump of processor
153   register state when an unexpected exception occurs during execution of
154   BL31. This option defaults to the value of ``DEBUG`` - i.e. by default
155   this is only enabled for a debug build of the firmware.
156
157-  ``CREATE_KEYS``: This option is used when ``GENERATE_COT=1``. It tells the
158   certificate generation tool to create new keys in case no valid keys are
159   present or specified. Allowed options are '0' or '1'. Default is '1'.
160
161-  ``CTX_INCLUDE_AARCH32_REGS`` : Boolean option that, when set to 1, will cause
162   the AArch32 system registers to be included when saving and restoring the
163   CPU context. The option must be set to 0 for AArch64-only platforms (that
164   is on hardware that does not implement AArch32, or at least not at EL1 and
165   higher ELs). Default value is 1.
166
167-  ``CTX_INCLUDE_EL2_REGS`` : This boolean option provides context save/restore
168   operations when entering/exiting an EL2 execution context. This is of primary
169   interest when Armv8.4-SecEL2 extension is implemented. Default is 0 (disabled).
170   This option must be equal to 1 (enabled) when ``SPD=spmd`` and
171   ``SPMD_SPM_AT_SEL2`` is set.
172
173-  ``CTX_INCLUDE_FPREGS``: Boolean option that, when set to 1, will cause the FP
174   registers to be included when saving and restoring the CPU context. Default
175   is 0.
176
177-  ``CTX_INCLUDE_NEVE_REGS``: Boolean option that, when set to 1, will cause the
178   Armv8.4-NV registers to be saved/restored when entering/exiting an EL2
179   execution context. Default value is 0.
180
181-  ``CTX_INCLUDE_PAUTH_REGS``: Boolean option that, when set to 1, enables
182   Pointer Authentication for Secure world. This will cause the ARMv8.3-PAuth
183   registers to be included when saving and restoring the CPU context as
184   part of world switch. Default value is 0.
185   Note that Pointer Authentication is enabled for Non-secure world irrespective
186   of the value of this flag if the CPU supports it.
187
188-  ``DEBUG``: Chooses between a debug and release build. It can take either 0
189   (release) or 1 (debug) as values. 0 is the default.
190
191-  ``DECRYPTION_SUPPORT``: This build flag enables the user to select the
192   authenticated decryption algorithm to be used to decrypt firmware/s during
193   boot. It accepts 2 values: ``aes_gcm`` and ``none``. The default value of
194   this flag is ``none`` to disable firmware decryption which is an optional
195   feature as per TBBR.
196
197-  ``DISABLE_BIN_GENERATION``: Boolean option to disable the generation
198   of the binary image. If set to 1, then only the ELF image is built.
199   0 is the default.
200
201-  ``DISABLE_MTPMU``: Boolean option to disable FEAT_MTPMU if implemented
202   (Armv8.6 onwards). Its default value is 0 to keep consistency with platforms
203   that do not implement FEAT_MTPMU. For more information on FEAT_MTPMU,
204   check the latest Arm ARM.
205
206-  ``DYN_DISABLE_AUTH``: Provides the capability to dynamically disable Trusted
207   Board Boot authentication at runtime. This option is meant to be enabled only
208   for development platforms. ``TRUSTED_BOARD_BOOT`` flag must be set if this
209   flag has to be enabled. 0 is the default.
210
211-  ``E``: Boolean option to make warnings into errors. Default is 1.
212
213-  ``EL3_PAYLOAD_BASE``: This option enables booting an EL3 payload instead of
214   the normal boot flow. It must specify the entry point address of the EL3
215   payload. Please refer to the "Booting an EL3 payload" section for more
216   details.
217
218-  ``ENABLE_AMU``: Boolean option to enable Activity Monitor Unit extensions.
219   This is an optional architectural feature available on v8.4 onwards. Some
220   v8.2 implementations also implement an AMU and this option can be used to
221   enable this feature on those systems as well. Default is 0.
222
223-  ``ENABLE_AMU_AUXILIARY_COUNTERS``: Enables support for AMU auxiliary counters
224   (also known as group 1 counters). These are implementation-defined counters,
225   and as such require additional platform configuration. Default is 0.
226
227-  ``ENABLE_AMU_FCONF``: Enables configuration of the AMU through FCONF, which
228   allows platforms with auxiliary counters to describe them via the
229   ``HW_CONFIG`` device tree blob. Default is 0.
230
231-  ``ENABLE_ASSERTIONS``: This option controls whether or not calls to ``assert()``
232   are compiled out. For debug builds, this option defaults to 1, and calls to
233   ``assert()`` are left in place. For release builds, this option defaults to 0
234   and calls to ``assert()`` function are compiled out. This option can be set
235   independently of ``DEBUG``. It can also be used to hide any auxiliary code
236   that is only required for the assertion and does not fit in the assertion
237   itself.
238
239-  ``ENABLE_BACKTRACE``: This option controls whether to enable backtrace
240   dumps or not. It is supported in both AArch64 and AArch32. However, in
241   AArch32 the format of the frame records are not defined in the AAPCS and they
242   are defined by the implementation. This implementation of backtrace only
243   supports the format used by GCC when T32 interworking is disabled. For this
244   reason enabling this option in AArch32 will force the compiler to only
245   generate A32 code. This option is enabled by default only in AArch64 debug
246   builds, but this behaviour can be overridden in each platform's Makefile or
247   in the build command line.
248
249-  ``ENABLE_FEAT_HCX``: This option sets the bit SCR_EL3.HXEn in EL3 to allow
250   access to HCRX_EL2 (extended hypervisor control register) from EL2 as well as
251   adding HCRX_EL2 to the EL2 context save/restore operations.
252
253-  ``ENABLE_LTO``: Boolean option to enable Link Time Optimization (LTO)
254   support in GCC for TF-A. This option is currently only supported for
255   AArch64. Default is 0.
256
257-  ``ENABLE_MPAM_FOR_LOWER_ELS``: Boolean option to enable lower ELs to use MPAM
258   feature. MPAM is an optional Armv8.4 extension that enables various memory
259   system components and resources to define partitions; software running at
260   various ELs can assign themselves to desired partition to control their
261   performance aspects.
262
263   When this option is set to ``1``, EL3 allows lower ELs to access their own
264   MPAM registers without trapping into EL3. This option doesn't make use of
265   partitioning in EL3, however. Platform initialisation code should configure
266   and use partitions in EL3 as required. This option defaults to ``0``.
267
268-  ``ENABLE_MPMM``: Boolean option to enable support for the Maximum Power
269   Mitigation Mechanism supported by certain Arm cores, which allows the SoC
270   firmware to detect and limit high activity events to assist in SoC processor
271   power domain dynamic power budgeting and limit the triggering of whole-rail
272   (i.e. clock chopping) responses to overcurrent conditions. Defaults to ``0``.
273
274-  ``ENABLE_MPMM_FCONF``: Enables configuration of MPMM through FCONF, which
275   allows platforms with cores supporting MPMM to describe them via the
276   ``HW_CONFIG`` device tree blob. Default is 0.
277
278-  ``ENABLE_PIE``: Boolean option to enable Position Independent Executable(PIE)
279   support within generic code in TF-A. This option is currently only supported
280   in BL2_AT_EL3, BL31, and BL32 (TSP) for AARCH64 binaries, and in BL32
281   (SP_min) for AARCH32. Default is 0.
282
283-  ``ENABLE_PMF``: Boolean option to enable support for optional Performance
284   Measurement Framework(PMF). Default is 0.
285
286-  ``ENABLE_PSCI_STAT``: Boolean option to enable support for optional PSCI
287   functions ``PSCI_STAT_RESIDENCY`` and ``PSCI_STAT_COUNT``. Default is 0.
288   In the absence of an alternate stat collection backend, ``ENABLE_PMF`` must
289   be enabled. If ``ENABLE_PMF`` is set, the residency statistics are tracked in
290   software.
291
292- ``ENABLE_RME``: Boolean option to enable support for the ARMv9 Realm
293   Management Extension. Default value is 0. This is currently an experimental
294   feature.
295
296-  ``ENABLE_RUNTIME_INSTRUMENTATION``: Boolean option to enable runtime
297   instrumentation which injects timestamp collection points into TF-A to
298   allow runtime performance to be measured. Currently, only PSCI is
299   instrumented. Enabling this option enables the ``ENABLE_PMF`` build option
300   as well. Default is 0.
301
302-  ``ENABLE_SME_FOR_NS``: Boolean option to enable Scalable Matrix Extension
303   (SME), SVE, and FPU/SIMD for the non-secure world only. These features share
304   registers so are enabled together. Using this option without
305   ENABLE_SME_FOR_SWD=1 will cause SME, SVE, and FPU/SIMD instructions in secure
306   world to trap to EL3. SME is an optional architectural feature for AArch64
307   and TF-A support is experimental. At this time, this build option cannot be
308   used on systems that have SPD=spmd or ENABLE_RME, and attempting to build
309   with these options will fail. Default is 0.
310
311-  ``ENABLE_SME_FOR_SWD``: Boolean option to enable the Scalable Matrix
312   Extension for secure world use along with SVE and FPU/SIMD, ENABLE_SME_FOR_NS
313   must also be set to use this. If enabling this, the secure world MUST
314   handle context switching for SME, SVE, and FPU/SIMD registers to ensure that
315   no data is leaked to non-secure world. This is experimental. Default is 0.
316
317-  ``ENABLE_SPE_FOR_LOWER_ELS`` : Boolean option to enable Statistical Profiling
318   extensions. This is an optional architectural feature for AArch64.
319   The default is 1 but is automatically disabled when the target architecture
320   is AArch32.
321
322-  ``ENABLE_SVE_FOR_NS``: Boolean option to enable Scalable Vector Extension
323   (SVE) for the Non-secure world only. SVE is an optional architectural feature
324   for AArch64. Note that when SVE is enabled for the Non-secure world, access
325   to SIMD and floating-point functionality from the Secure world is disabled by
326   default and controlled with ENABLE_SVE_FOR_SWD.
327   This is to avoid corruption of the Non-secure world data in the Z-registers
328   which are aliased by the SIMD and FP registers. The build option is not
329   compatible with the ``CTX_INCLUDE_FPREGS`` build option, and will raise an
330   assert on platforms where SVE is implemented and ``ENABLE_SVE_FOR_NS`` set to
331   1. The default is 1 but is automatically disabled when ENABLE_SME_FOR_NS=1
332   since SME encompasses SVE.
333
334-  ``ENABLE_SVE_FOR_SWD``: Boolean option to enable SVE for the Secure world.
335   SVE is an optional architectural feature for AArch64. Note that this option
336   requires ENABLE_SVE_FOR_NS to be enabled.  The default is 0 and it is
337   automatically disabled when the target architecture is AArch32.
338
339-  ``ENABLE_STACK_PROTECTOR``: String option to enable the stack protection
340   checks in GCC. Allowed values are "all", "strong", "default" and "none". The
341   default value is set to "none". "strong" is the recommended stack protection
342   level if this feature is desired. "none" disables the stack protection. For
343   all values other than "none", the ``plat_get_stack_protector_canary()``
344   platform hook needs to be implemented. The value is passed as the last
345   component of the option ``-fstack-protector-$ENABLE_STACK_PROTECTOR``.
346
347-  ``ENCRYPT_BL31``: Binary flag to enable encryption of BL31 firmware. This
348   flag depends on ``DECRYPTION_SUPPORT`` build flag.
349
350-  ``ENCRYPT_BL32``: Binary flag to enable encryption of Secure BL32 payload.
351   This flag depends on ``DECRYPTION_SUPPORT`` build flag.
352
353-  ``ENC_KEY``: A 32-byte (256-bit) symmetric key in hex string format. It could
354   either be SSK or BSSK depending on ``FW_ENC_STATUS`` flag. This value depends
355   on ``DECRYPTION_SUPPORT`` build flag.
356
357-  ``ENC_NONCE``: A 12-byte (96-bit) encryption nonce or Initialization Vector
358   (IV) in hex string format. This value depends on ``DECRYPTION_SUPPORT``
359   build flag.
360
361-  ``ERROR_DEPRECATED``: This option decides whether to treat the usage of
362   deprecated platform APIs, helper functions or drivers within Trusted
363   Firmware as error. It can take the value 1 (flag the use of deprecated
364   APIs as error) or 0. The default is 0.
365
366-  ``EL3_EXCEPTION_HANDLING``: When set to ``1``, enable handling of exceptions
367   targeted at EL3. When set ``0`` (default), no exceptions are expected or
368   handled at EL3, and a panic will result. This is supported only for AArch64
369   builds.
370
371-  ``EVENT_LOG_LEVEL``: Chooses the log level to use for Measured Boot when
372   ``MEASURED_BOOT`` is enabled. For a list of valid values, see ``LOG_LEVEL``.
373   Default value is 40 (LOG_LEVEL_INFO).
374
375-  ``FAULT_INJECTION_SUPPORT``: ARMv8.4 extensions introduced support for fault
376   injection from lower ELs, and this build option enables lower ELs to use
377   Error Records accessed via System Registers to inject faults. This is
378   applicable only to AArch64 builds.
379
380   This feature is intended for testing purposes only, and is advisable to keep
381   disabled for production images.
382
383-  ``FIP_NAME``: This is an optional build option which specifies the FIP
384   filename for the ``fip`` target. Default is ``fip.bin``.
385
386-  ``FWU_FIP_NAME``: This is an optional build option which specifies the FWU
387   FIP filename for the ``fwu_fip`` target. Default is ``fwu_fip.bin``.
388
389-  ``FW_ENC_STATUS``: Top level firmware's encryption numeric flag, values:
390
391   ::
392
393     0: Encryption is done with Secret Symmetric Key (SSK) which is common
394        for a class of devices.
395     1: Encryption is done with Binding Secret Symmetric Key (BSSK) which is
396        unique per device.
397
398   This flag depends on ``DECRYPTION_SUPPORT`` build flag.
399
400-  ``GENERATE_COT``: Boolean flag used to build and execute the ``cert_create``
401   tool to create certificates as per the Chain of Trust described in
402   :ref:`Trusted Board Boot`. The build system then calls ``fiptool`` to
403   include the certificates in the FIP and FWU_FIP. Default value is '0'.
404
405   Specify both ``TRUSTED_BOARD_BOOT=1`` and ``GENERATE_COT=1`` to include support
406   for the Trusted Board Boot feature in the BL1 and BL2 images, to generate
407   the corresponding certificates, and to include those certificates in the
408   FIP and FWU_FIP.
409
410   Note that if ``TRUSTED_BOARD_BOOT=0`` and ``GENERATE_COT=1``, the BL1 and BL2
411   images will not include support for Trusted Board Boot. The FIP will still
412   include the corresponding certificates. This FIP can be used to verify the
413   Chain of Trust on the host machine through other mechanisms.
414
415   Note that if ``TRUSTED_BOARD_BOOT=1`` and ``GENERATE_COT=0``, the BL1 and BL2
416   images will include support for Trusted Board Boot, but the FIP and FWU_FIP
417   will not include the corresponding certificates, causing a boot failure.
418
419-  ``GICV2_G0_FOR_EL3``: Unlike GICv3, the GICv2 architecture doesn't have
420   inherent support for specific EL3 type interrupts. Setting this build option
421   to ``1`` assumes GICv2 *Group 0* interrupts are expected to target EL3, both
422   by :ref:`platform abstraction layer<platform Interrupt Controller API>` and
423   :ref:`Interrupt Management Framework<Interrupt Management Framework>`.
424   This allows GICv2 platforms to enable features requiring EL3 interrupt type.
425   This also means that all GICv2 Group 0 interrupts are delivered to EL3, and
426   the Secure Payload interrupts needs to be synchronously handed over to Secure
427   EL1 for handling. The default value of this option is ``0``, which means the
428   Group 0 interrupts are assumed to be handled by Secure EL1.
429
430-  ``HANDLE_EA_EL3_FIRST``: When set to ``1``, External Aborts and SError
431   Interrupts will be always trapped in EL3 i.e. in BL31 at runtime. When set to
432   ``0`` (default), these exceptions will be trapped in the current exception
433   level (or in EL1 if the current exception level is EL0).
434
435-  ``HW_ASSISTED_COHERENCY``: On most Arm systems to-date, platform-specific
436   software operations are required for CPUs to enter and exit coherency.
437   However, newer systems exist where CPUs' entry to and exit from coherency
438   is managed in hardware. Such systems require software to only initiate these
439   operations, and the rest is managed in hardware, minimizing active software
440   management. In such systems, this boolean option enables TF-A to carry out
441   build and run-time optimizations during boot and power management operations.
442   This option defaults to 0 and if it is enabled, then it implies
443   ``WARMBOOT_ENABLE_DCACHE_EARLY`` is also enabled.
444
445   If this flag is disabled while the platform which TF-A is compiled for
446   includes cores that manage coherency in hardware, then a compilation error is
447   generated. This is based on the fact that a system cannot have, at the same
448   time, cores that manage coherency in hardware and cores that don't. In other
449   words, a platform cannot have, at the same time, cores that require
450   ``HW_ASSISTED_COHERENCY=1`` and cores that require
451   ``HW_ASSISTED_COHERENCY=0``.
452
453   Note that, when ``HW_ASSISTED_COHERENCY`` is enabled, version 2 of
454   translation library (xlat tables v2) must be used; version 1 of translation
455   library is not supported.
456
457-  ``INVERTED_MEMMAP``: memmap tool print by default lower addresses at the
458   bottom, higher addresses at the top. This build flag can be set to '1' to
459   invert this behavior. Lower addresses will be printed at the top and higher
460   addresses at the bottom.
461
462-  ``JUNO_AARCH32_EL3_RUNTIME``: This build flag enables you to execute EL3
463   runtime software in AArch32 mode, which is required to run AArch32 on Juno.
464   By default this flag is set to '0'. Enabling this flag builds BL1 and BL2 in
465   AArch64 and facilitates the loading of ``SP_MIN`` and BL33 as AArch32 executable
466   images.
467
468-  ``KEY_ALG``: This build flag enables the user to select the algorithm to be
469   used for generating the PKCS keys and subsequent signing of the certificate.
470   It accepts 3 values: ``rsa``, ``rsa_1_5`` and ``ecdsa``. The option
471   ``rsa_1_5`` is the legacy PKCS#1 RSA 1.5 algorithm which is not TBBR
472   compliant and is retained only for compatibility. The default value of this
473   flag is ``rsa`` which is the TBBR compliant PKCS#1 RSA 2.1 scheme.
474
475-  ``KEY_SIZE``: This build flag enables the user to select the key size for
476   the algorithm specified by ``KEY_ALG``. The valid values for ``KEY_SIZE``
477   depend on the chosen algorithm and the cryptographic module.
478
479   +-----------+------------------------------------+
480   |  KEY_ALG  |        Possible key sizes          |
481   +===========+====================================+
482   |    rsa    | 1024 , 2048 (default), 3072, 4096* |
483   +-----------+------------------------------------+
484   |   ecdsa   |            unavailable             |
485   +-----------+------------------------------------+
486
487   * Only 2048 bits size is available with CryptoCell 712 SBROM release 1.
488     Only 3072 bits size is available with CryptoCell 712 SBROM release 2.
489
490-  ``HASH_ALG``: This build flag enables the user to select the secure hash
491   algorithm. It accepts 3 values: ``sha256``, ``sha384`` and ``sha512``.
492   The default value of this flag is ``sha256``.
493
494-  ``LDFLAGS``: Extra user options appended to the linkers' command line in
495   addition to the one set by the build system.
496
497-  ``LOG_LEVEL``: Chooses the log level, which controls the amount of console log
498   output compiled into the build. This should be one of the following:
499
500   ::
501
502       0  (LOG_LEVEL_NONE)
503       10 (LOG_LEVEL_ERROR)
504       20 (LOG_LEVEL_NOTICE)
505       30 (LOG_LEVEL_WARNING)
506       40 (LOG_LEVEL_INFO)
507       50 (LOG_LEVEL_VERBOSE)
508
509   All log output up to and including the selected log level is compiled into
510   the build. The default value is 40 in debug builds and 20 in release builds.
511
512-  ``MEASURED_BOOT``: Boolean flag to include support for the Measured Boot
513   feature. If this flag is enabled ``TRUSTED_BOARD_BOOT`` must be set as well
514   in order to provide trust that the code taking the measurements and recording
515   them has not been tampered with.
516
517   This option defaults to 0.
518
519-  ``NON_TRUSTED_WORLD_KEY``: This option is used when ``GENERATE_COT=1``. It
520   specifies the file that contains the Non-Trusted World private key in PEM
521   format. If ``SAVE_KEYS=1``, this file name will be used to save the key.
522
523-  ``NS_BL2U``: Path to NS_BL2U image in the host file system. This image is
524   optional. It is only needed if the platform makefile specifies that it
525   is required in order to build the ``fwu_fip`` target.
526
527-  ``NS_TIMER_SWITCH``: Enable save and restore for non-secure timer register
528   contents upon world switch. It can take either 0 (don't save and restore) or
529   1 (do save and restore). 0 is the default. An SPD may set this to 1 if it
530   wants the timer registers to be saved and restored.
531
532-  ``OVERRIDE_LIBC``: This option allows platforms to override the default libc
533   for the BL image. It can be either 0 (include) or 1 (remove). The default
534   value is 0.
535
536-  ``PL011_GENERIC_UART``: Boolean option to indicate the PL011 driver that
537   the underlying hardware is not a full PL011 UART but a minimally compliant
538   generic UART, which is a subset of the PL011. The driver will not access
539   any register that is not part of the SBSA generic UART specification.
540   Default value is 0 (a full PL011 compliant UART is present).
541
542-  ``PLAT``: Choose a platform to build TF-A for. The chosen platform name
543   must be subdirectory of any depth under ``plat/``, and must contain a
544   platform makefile named ``platform.mk``. For example, to build TF-A for the
545   Arm Juno board, select PLAT=juno.
546
547-  ``PRELOADED_BL33_BASE``: This option enables booting a preloaded BL33 image
548   instead of the normal boot flow. When defined, it must specify the entry
549   point address for the preloaded BL33 image. This option is incompatible with
550   ``EL3_PAYLOAD_BASE``. If both are defined, ``EL3_PAYLOAD_BASE`` has priority
551   over ``PRELOADED_BL33_BASE``.
552
553-  ``PROGRAMMABLE_RESET_ADDRESS``: This option indicates whether the reset
554   vector address can be programmed or is fixed on the platform. It can take
555   either 0 (fixed) or 1 (programmable). Default is 0. If the platform has a
556   programmable reset address, it is expected that a CPU will start executing
557   code directly at the right address, both on a cold and warm reset. In this
558   case, there is no need to identify the entrypoint on boot and the boot path
559   can be optimised. The ``plat_get_my_entrypoint()`` platform porting interface
560   does not need to be implemented in this case.
561
562-  ``PSCI_EXTENDED_STATE_ID``: As per PSCI1.0 Specification, there are 2 formats
563   possible for the PSCI power-state parameter: original and extended State-ID
564   formats. This flag if set to 1, configures the generic PSCI layer to use the
565   extended format. The default value of this flag is 0, which means by default
566   the original power-state format is used by the PSCI implementation. This flag
567   should be specified by the platform makefile and it governs the return value
568   of PSCI_FEATURES API for CPU_SUSPEND smc function id. When this option is
569   enabled on Arm platforms, the option ``ARM_RECOM_STATE_ID_ENC`` needs to be
570   set to 1 as well.
571
572-  ``RAS_EXTENSION``: When set to ``1``, enable Armv8.2 RAS features. RAS features
573   are an optional extension for pre-Armv8.2 CPUs, but are mandatory for Armv8.2
574   or later CPUs.
575
576   When ``RAS_EXTENSION`` is set to ``1``, ``HANDLE_EA_EL3_FIRST`` must also be
577   set to ``1``.
578
579   This option is disabled by default.
580
581-  ``RESET_TO_BL31``: Enable BL31 entrypoint as the CPU reset vector instead
582   of the BL1 entrypoint. It can take the value 0 (CPU reset to BL1
583   entrypoint) or 1 (CPU reset to BL31 entrypoint).
584   The default value is 0.
585
586-  ``RESET_TO_SP_MIN``: SP_MIN is the minimal AArch32 Secure Payload provided
587   in TF-A. This flag configures SP_MIN entrypoint as the CPU reset vector
588   instead of the BL1 entrypoint. It can take the value 0 (CPU reset to BL1
589   entrypoint) or 1 (CPU reset to SP_MIN entrypoint). The default value is 0.
590
591-  ``ROT_KEY``: This option is used when ``GENERATE_COT=1``. It specifies the
592   file that contains the ROT private key in PEM format and enforces public key
593   hash generation. If ``SAVE_KEYS=1``, this
594   file name will be used to save the key.
595
596-  ``SAVE_KEYS``: This option is used when ``GENERATE_COT=1``. It tells the
597   certificate generation tool to save the keys used to establish the Chain of
598   Trust. Allowed options are '0' or '1'. Default is '0' (do not save).
599
600-  ``SCP_BL2``: Path to SCP_BL2 image in the host file system. This image is optional.
601   If a SCP_BL2 image is present then this option must be passed for the ``fip``
602   target.
603
604-  ``SCP_BL2_KEY``: This option is used when ``GENERATE_COT=1``. It specifies the
605   file that contains the SCP_BL2 private key in PEM format. If ``SAVE_KEYS=1``,
606   this file name will be used to save the key.
607
608-  ``SCP_BL2U``: Path to SCP_BL2U image in the host file system. This image is
609   optional. It is only needed if the platform makefile specifies that it
610   is required in order to build the ``fwu_fip`` target.
611
612-  ``SDEI_SUPPORT``: Setting this to ``1`` enables support for Software
613   Delegated Exception Interface to BL31 image. This defaults to ``0``.
614
615   When set to ``1``, the build option ``EL3_EXCEPTION_HANDLING`` must also be
616   set to ``1``.
617
618-  ``SEPARATE_CODE_AND_RODATA``: Whether code and read-only data should be
619   isolated on separate memory pages. This is a trade-off between security and
620   memory usage. See "Isolating code and read-only data on separate memory
621   pages" section in :ref:`Firmware Design`. This flag is disabled by default
622   and affects all BL images.
623
624-  ``SEPARATE_NOBITS_REGION``: Setting this option to ``1`` allows the NOBITS
625   sections of BL31 (.bss, stacks, page tables, and coherent memory) to be
626   allocated in RAM discontiguous from the loaded firmware image. When set, the
627   platform is expected to provide definitions for ``BL31_NOBITS_BASE`` and
628   ``BL31_NOBITS_LIMIT``. When the option is ``0`` (the default), NOBITS
629   sections are placed in RAM immediately following the loaded firmware image.
630
631-  ``SMC_PCI_SUPPORT``: This option allows platforms to handle PCI configuration
632   access requests via a standard SMCCC defined in `DEN0115`_. When combined with
633   UEFI+ACPI this can provide a certain amount of OS forward compatibility
634   with newer platforms that aren't ECAM compliant.
635
636-  ``SPD``: Choose a Secure Payload Dispatcher component to be built into TF-A.
637   This build option is only valid if ``ARCH=aarch64``. The value should be
638   the path to the directory containing the SPD source, relative to
639   ``services/spd/``; the directory is expected to contain a makefile called
640   ``<spd-value>.mk``. The SPM Dispatcher standard service is located in
641   services/std_svc/spmd and enabled by ``SPD=spmd``. The SPM Dispatcher
642   cannot be enabled when the ``SPM_MM`` option is enabled.
643
644-  ``SPIN_ON_BL1_EXIT``: This option introduces an infinite loop in BL1. It can
645   take either 0 (no loop) or 1 (add a loop). 0 is the default. This loop stops
646   execution in BL1 just before handing over to BL31. At this point, all
647   firmware images have been loaded in memory, and the MMU and caches are
648   turned off. Refer to the "Debugging options" section for more details.
649
650-  ``SPMD_SPM_AT_SEL2`` : this boolean option is used jointly with the SPM
651   Dispatcher option (``SPD=spmd``). When enabled (1) it indicates the SPMC
652   component runs at the S-EL2 execution state provided by the Armv8.4-SecEL2
653   extension. This is the default when enabling the SPM Dispatcher. When
654   disabled (0) it indicates the SPMC component runs at the S-EL1 execution
655   state. This latter configuration supports pre-Armv8.4 platforms (aka not
656   implementing the Armv8.4-SecEL2 extension).
657
658-  ``SPM_MM`` : Boolean option to enable the Management Mode (MM)-based Secure
659   Partition Manager (SPM) implementation. The default value is ``0``
660   (disabled). This option cannot be enabled (``1``) when SPM Dispatcher is
661   enabled (``SPD=spmd``).
662
663-  ``SP_LAYOUT_FILE``: Platform provided path to JSON file containing the
664   description of secure partitions. The build system will parse this file and
665   package all secure partition blobs into the FIP. This file is not
666   necessarily part of TF-A tree. Only available when ``SPD=spmd``.
667
668-  ``SP_MIN_WITH_SECURE_FIQ``: Boolean flag to indicate the SP_MIN handles
669   secure interrupts (caught through the FIQ line). Platforms can enable
670   this directive if they need to handle such interruption. When enabled,
671   the FIQ are handled in monitor mode and non secure world is not allowed
672   to mask these events. Platforms that enable FIQ handling in SP_MIN shall
673   implement the api ``sp_min_plat_fiq_handler()``. The default value is 0.
674
675-  ``TRUSTED_BOARD_BOOT``: Boolean flag to include support for the Trusted Board
676   Boot feature. When set to '1', BL1 and BL2 images include support to load
677   and verify the certificates and images in a FIP, and BL1 includes support
678   for the Firmware Update. The default value is '0'. Generation and inclusion
679   of certificates in the FIP and FWU_FIP depends upon the value of the
680   ``GENERATE_COT`` option.
681
682   .. warning::
683      This option depends on ``CREATE_KEYS`` to be enabled. If the keys
684      already exist in disk, they will be overwritten without further notice.
685
686-  ``TRUSTED_WORLD_KEY``: This option is used when ``GENERATE_COT=1``. It
687   specifies the file that contains the Trusted World private key in PEM
688   format. If ``SAVE_KEYS=1``, this file name will be used to save the key.
689
690-  ``TSP_INIT_ASYNC``: Choose BL32 initialization method as asynchronous or
691   synchronous, (see "Initializing a BL32 Image" section in
692   :ref:`Firmware Design`). It can take the value 0 (BL32 is initialized using
693   synchronous method) or 1 (BL32 is initialized using asynchronous method).
694   Default is 0.
695
696-  ``TSP_NS_INTR_ASYNC_PREEMPT``: A non zero value enables the interrupt
697   routing model which routes non-secure interrupts asynchronously from TSP
698   to EL3 causing immediate preemption of TSP. The EL3 is responsible
699   for saving and restoring the TSP context in this routing model. The
700   default routing model (when the value is 0) is to route non-secure
701   interrupts to TSP allowing it to save its context and hand over
702   synchronously to EL3 via an SMC.
703
704   .. note::
705      When ``EL3_EXCEPTION_HANDLING`` is ``1``, ``TSP_NS_INTR_ASYNC_PREEMPT``
706      must also be set to ``1``.
707
708-  ``USE_ARM_LINK``: This flag determines whether to enable support for ARM
709   linker. When the ``LINKER`` build variable points to the armlink linker,
710   this flag is enabled automatically. To enable support for armlink, platforms
711   will have to provide a scatter file for the BL image. Currently, Tegra
712   platforms use the armlink support to compile BL3-1 images.
713
714-  ``USE_COHERENT_MEM``: This flag determines whether to include the coherent
715   memory region in the BL memory map or not (see "Use of Coherent memory in
716   TF-A" section in :ref:`Firmware Design`). It can take the value 1
717   (Coherent memory region is included) or 0 (Coherent memory region is
718   excluded). Default is 1.
719
720-  ``USE_DEBUGFS``: When set to 1 this option activates an EXPERIMENTAL feature
721   exposing a virtual filesystem interface through BL31 as a SiP SMC function.
722   Default is 0.
723
724-  ``ARM_IO_IN_DTB``: This flag determines whether to use IO based on the
725   firmware configuration framework. This will move the io_policies into a
726   configuration device tree, instead of static structure in the code base.
727
728-  ``COT_DESC_IN_DTB``: This flag determines whether to create COT descriptors
729   at runtime using fconf. If this flag is enabled, COT descriptors are
730   statically captured in tb_fw_config file in the form of device tree nodes
731   and properties. Currently, COT descriptors used by BL2 are moved to the
732   device tree and COT descriptors used by BL1 are retained in the code
733   base statically.
734
735-  ``SDEI_IN_FCONF``: This flag determines whether to configure SDEI setup in
736   runtime using firmware configuration framework. The platform specific SDEI
737   shared and private events configuration is retrieved from device tree rather
738   than static C structures at compile time. This is only supported if
739   SDEI_SUPPORT build flag is enabled.
740
741-  ``SEC_INT_DESC_IN_FCONF``: This flag determines whether to configure Group 0
742   and Group1 secure interrupts using the firmware configuration framework. The
743   platform specific secure interrupt property descriptor is retrieved from
744   device tree in runtime rather than depending on static C structure at compile
745   time.
746
747-  ``USE_ROMLIB``: This flag determines whether library at ROM will be used.
748   This feature creates a library of functions to be placed in ROM and thus
749   reduces SRAM usage. Refer to :ref:`Library at ROM` for further details. Default
750   is 0.
751
752-  ``V``: Verbose build. If assigned anything other than 0, the build commands
753   are printed. Default is 0.
754
755-  ``VERSION_STRING``: String used in the log output for each TF-A image.
756   Defaults to a string formed by concatenating the version number, build type
757   and build string.
758
759-  ``W``: Warning level. Some compiler warning options of interest have been
760   regrouped and put in the root Makefile. This flag can take the values 0 to 3,
761   each level enabling more warning options. Default is 0.
762
763-  ``WARMBOOT_ENABLE_DCACHE_EARLY`` : Boolean option to enable D-cache early on
764   the CPU after warm boot. This is applicable for platforms which do not
765   require interconnect programming to enable cache coherency (eg: single
766   cluster platforms). If this option is enabled, then warm boot path
767   enables D-caches immediately after enabling MMU. This option defaults to 0.
768
769-  ``SUPPORT_STACK_MEMTAG``: This flag determines whether to enable memory
770   tagging for stack or not. It accepts 2 values: ``yes`` and ``no``. The
771   default value of this flag is ``no``. Note this option must be enabled only
772   for ARM architecture greater than Armv8.5-A.
773
774-  ``ERRATA_SPECULATIVE_AT``: This flag determines whether to enable ``AT``
775   speculative errata workaround or not. It accepts 2 values: ``1`` and ``0``.
776   The default value of this flag is ``0``.
777
778   ``AT`` speculative errata workaround disables stage1 page table walk for
779   lower ELs (EL1 and EL0) in EL3 so that ``AT`` speculative fetch at any point
780   produces either the correct result or failure without TLB allocation.
781
782   This boolean option enables errata for all below CPUs.
783
784   +---------+--------------+-------------------------+
785   | Errata  |      CPU     |     Workaround Define   |
786   +=========+==============+=========================+
787   | 1165522 |  Cortex-A76  |  ``ERRATA_A76_1165522`` |
788   +---------+--------------+-------------------------+
789   | 1319367 |  Cortex-A72  |  ``ERRATA_A72_1319367`` |
790   +---------+--------------+-------------------------+
791   | 1319537 |  Cortex-A57  |  ``ERRATA_A57_1319537`` |
792   +---------+--------------+-------------------------+
793   | 1530923 |  Cortex-A55  |  ``ERRATA_A55_1530923`` |
794   +---------+--------------+-------------------------+
795   | 1530924 |  Cortex-A53  |  ``ERRATA_A53_1530924`` |
796   +---------+--------------+-------------------------+
797
798   .. note::
799      This option is enabled by build only if platform sets any of above defines
800      mentioned in ’Workaround Define' column in the table.
801      If this option is enabled for the EL3 software then EL2 software also must
802      implement this workaround due to the behaviour of the errata mentioned
803      in new SDEN document which will get published soon.
804
805- ``RAS_TRAP_LOWER_EL_ERR_ACCESS``: This flag enables/disables the SCR_EL3.TERR
806  bit, to trap access to the RAS ERR and RAS ERX registers from lower ELs.
807  This flag is disabled by default.
808
809- ``OPENSSL_DIR``: This flag is used to provide the installed openssl directory
810  path on the host machine which is used to build certificate generation and
811  firmware encryption tool.
812
813- ``USE_SP804_TIMER``: Use the SP804 timer instead of the Generic Timer for
814  functions that wait for an arbitrary time length (udelay and mdelay). The
815  default value is 0.
816
817- ``ENABLE_TRBE_FOR_NS``: This flag is used to enable access of trace buffer
818  control registers from NS ELs, NS-EL2 or NS-EL1(when NS-EL2 is implemented
819  but unused) when FEAT_TRBE is implemented. TRBE is an optional architectural
820  feature for AArch64. The default is 0 and it is automatically disabled when
821  the target architecture is AArch32.
822
823- ``ENABLE_SYS_REG_TRACE_FOR_NS``: Boolean option to enable trace system
824  registers access from NS ELs, NS-EL2 or NS-EL1 (when NS-EL2 is implemented
825  but unused). This feature is available if trace unit such as ETMv4.x, and
826  ETE(extending ETM feature) is implemented. This flag is disabled by default.
827
828- ``ENABLE_TRF_FOR_NS``: Boolean option to enable trace filter control registers
829  access from NS ELs, NS-EL2 or NS-EL1 (when NS-EL2 is implemented but unused),
830  if FEAT_TRF is implemented. This flag is disabled by default.
831
832GICv3 driver options
833--------------------
834
835GICv3 driver files are included using directive:
836
837``include drivers/arm/gic/v3/gicv3.mk``
838
839The driver can be configured with the following options set in the platform
840makefile:
841
842-  ``GICV3_SUPPORT_GIC600``: Add support for the GIC-600 variants of GICv3.
843   Enabling this option will add runtime detection support for the
844   GIC-600, so is safe to select even for a GIC500 implementation.
845   This option defaults to 0.
846
847- ``GICV3_SUPPORT_GIC600AE_FMU``: Add support for the Fault Management Unit
848   for GIC-600 AE. Enabling this option will introduce support to initialize
849   the FMU. Platforms should call the init function during boot to enable the
850   FMU and its safety mechanisms. This option defaults to 0.
851
852-  ``GICV3_IMPL_GIC600_MULTICHIP``: Selects GIC-600 variant with multichip
853   functionality. This option defaults to 0
854
855-  ``GICV3_OVERRIDE_DISTIF_PWR_OPS``: Allows override of default implementation
856   of ``arm_gicv3_distif_pre_save`` and ``arm_gicv3_distif_post_restore``
857   functions. This is required for FVP platform which need to simulate GIC save
858   and restore during SYSTEM_SUSPEND without powering down GIC. Default is 0.
859
860-  ``GIC_ENABLE_V4_EXTN`` : Enables GICv4 related changes in GICv3 driver.
861   This option defaults to 0.
862
863-  ``GIC_EXT_INTID``: When set to ``1``, GICv3 driver will support extended
864   PPI (1056-1119) and SPI (4096-5119) range. This option defaults to 0.
865
866Debugging options
867-----------------
868
869To compile a debug version and make the build more verbose use
870
871.. code:: shell
872
873    make PLAT=<platform> DEBUG=1 V=1 all
874
875AArch64 GCC uses DWARF version 4 debugging symbols by default. Some tools (for
876example DS-5) might not support this and may need an older version of DWARF
877symbols to be emitted by GCC. This can be achieved by using the
878``-gdwarf-<version>`` flag, with the version being set to 2 or 3. Setting the
879version to 2 is recommended for DS-5 versions older than 5.16.
880
881When debugging logic problems it might also be useful to disable all compiler
882optimizations by using ``-O0``.
883
884.. warning::
885   Using ``-O0`` could cause output images to be larger and base addresses
886   might need to be recalculated (see the **Memory layout on Arm development
887   platforms** section in the :ref:`Firmware Design`).
888
889Extra debug options can be passed to the build system by setting ``CFLAGS`` or
890``LDFLAGS``:
891
892.. code:: shell
893
894    CFLAGS='-O0 -gdwarf-2'                                     \
895    make PLAT=<platform> DEBUG=1 V=1 all
896
897Note that using ``-Wl,`` style compilation driver options in ``CFLAGS`` will be
898ignored as the linker is called directly.
899
900It is also possible to introduce an infinite loop to help in debugging the
901post-BL2 phase of TF-A. This can be done by rebuilding BL1 with the
902``SPIN_ON_BL1_EXIT=1`` build flag. Refer to the :ref:`build_options_common`
903section. In this case, the developer may take control of the target using a
904debugger when indicated by the console output. When using DS-5, the following
905commands can be used:
906
907::
908
909    # Stop target execution
910    interrupt
911
912    #
913    # Prepare your debugging environment, e.g. set breakpoints
914    #
915
916    # Jump over the debug loop
917    set var $AARCH64::$Core::$PC = $AARCH64::$Core::$PC + 4
918
919    # Resume execution
920    continue
921
922Firmware update options
923-----------------------
924
925-  ``NR_OF_FW_BANKS``: Define the number of firmware banks. This flag is used
926   in defining the firmware update metadata structure. This flag is by default
927   set to '2'.
928
929-  ``NR_OF_IMAGES_IN_FW_BANK``: Define the number of firmware images in each
930   firmware bank. Each firmware bank must have the same number of images as per
931   the `PSA FW update specification`_.
932   This flag is used in defining the firmware update metadata structure. This
933   flag is by default set to '1'.
934
935-  ``PSA_FWU_SUPPORT``: Enable the firmware update mechanism as per the
936   `PSA FW update specification`_. The default value is 0, and this is an
937   experimental feature.
938   PSA firmware update implementation has some limitations, such as BL2 is
939   not part of the protocol-updatable images, if BL2 needs to be updated, then
940   it should be done through another platform-defined mechanism, and it assumes
941   that the platform's hardware supports CRC32 instructions.
942
943--------------
944
945*Copyright (c) 2019-2021, Arm Limited. All rights reserved.*
946
947.. _DEN0115: https://developer.arm.com/docs/den0115/latest
948.. _PSA FW update specification: https://developer.arm.com/documentation/den0118/a/
949