Performing an Initial Build
===========================

-  Before building TF-A, the environment variable ``CROSS_COMPILE`` must point
   to your cross compiler.

   For AArch64:

   .. code:: shell

       export CROSS_COMPILE=<path-to-aarch64-gcc>/bin/aarch64-none-elf-

   For AArch32:

   .. code:: shell

       export CROSS_COMPILE=<path-to-aarch32-gcc>/bin/arm-none-eabi-

   It is possible to build TF-A using Clang or Arm Compiler 6. To do so
   ``CC`` needs to point to the clang or armclang binary, which will
   also select the clang or armclang assembler. Arm Compiler 6 will be selected
   when the base name of the path assigned to ``CC`` matches the string
   'armclang'. GNU binutils are required since the TF-A build system doesn't
   currently support Arm Scatter files. Meaning the GNU linker is used by
   default for Arm Compiler 6. Because of this dependency, ``CROSS_COMPILE``
   should be set as described above.

   For AArch64 using Arm Compiler 6:

   .. code:: shell

       export CROSS_COMPILE=<path-to-aarch64-gcc>/bin/aarch64-none-elf-
       make CC=<path-to-armclang>/bin/armclang PLAT=<platform> all

   On the other hand, Clang uses LLVM linker (LLD) and other LLVM binutils by
   default instead of GNU utilities (LLVM linker (LLD) 14.0.0 is known to
   work with TF-A). ``CROSS_COMPILE`` need not be set for Clang. Please note,
   that the default linker may be manually overridden using the ``LD`` variable.

   Clang will be selected when the base name of the path assigned to ``CC``
   contains the string 'clang'. This is to allow both clang and clang-X.Y
   to work.

   For AArch64 using clang:

   .. code:: shell

       make CC=<path-to-clang>/bin/clang PLAT=<platform> all

-  Change to the root directory of the TF-A source tree and build.

   For AArch64:

   .. code:: shell

       make PLAT=<platform> all

   For AArch32:

   .. code:: shell

       make PLAT=<platform> ARCH=aarch32 AARCH32_SP=sp_min all

   Notes:

   -  If ``PLAT`` is not specified, ``fvp`` is assumed by default. See the
      :ref:`Build Options` document for more information on available build
      options.

   -  (AArch32 only) Currently only ``PLAT=fvp`` is supported.

   -  (AArch32 only) ``AARCH32_SP`` is the AArch32 EL3 Runtime Software and it
      corresponds to the BL32 image. A minimal ``AARCH32_SP``, sp_min, is
      provided by TF-A to demonstrate how PSCI Library can be integrated with
      an AArch32 EL3 Runtime Software. Some AArch32 EL3 Runtime Software may
      include other runtime services, for example Trusted OS services. A guide
      to integrate PSCI library with AArch32 EL3 Runtime Software can be found
      at :ref:`PSCI Library Integration guide for Armv8-A AArch32 systems`.

   -  (AArch64 only) The TSP (Test Secure Payload), corresponding to the BL32
      image, is not compiled in by default. Refer to the
      :ref:`Test Secure Payload (TSP) and Dispatcher (TSPD)` document for
      details on building the TSP.

   -  By default this produces a release version of the build. To produce a
      debug version instead, refer to the "Debugging options" section below.

   -  The build process creates products in a ``build`` directory tree, building
      the objects and binaries for each boot loader stage in separate
      sub-directories. The following boot loader binary files are created
      from the corresponding ELF files:

      -  ``build/<platform>/<build-type>/bl1.bin``
      -  ``build/<platform>/<build-type>/bl2.bin``
      -  ``build/<platform>/<build-type>/bl31.bin`` (AArch64 only)
      -  ``build/<platform>/<build-type>/bl32.bin`` (mandatory for AArch32)

      where ``<platform>`` is the name of the chosen platform and ``<build-type>``
      is either ``debug`` or ``release``. The actual number of images might differ
      depending on the platform.

-  Build products for a specific build variant can be removed using:

   .. code:: shell

       make DEBUG=<D> PLAT=<platform> clean

   ... where ``<D>`` is ``0`` or ``1``, as specified when building.

   The build tree can be removed completely using:

   .. code:: shell

       make realclean

--------------

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