Build instructions


The build process was changed a lot in Q3 2023 and included into the release v2.0. For building instructions for early versions please refer to the documentation of respective versions.

As you know from the introduction TF-M implements SPE with a set of secure services. TF-M application as NSPE client uses those services through isolation boundary via PSA-FF-M API. Both SPE and NSPE are separate binaries and built independently. SPE and NSPE binaries are combined and signed making the final image for downloading onto targets when building NSPE.


This document describes the process of building a single SPE alone. Refer to Building Tests on how to build TF-M regression tests and PSA Arch tests to verify TF-M.

TF-M uses CMake v3.15 or higher. Before starting please make sure you have all required software installed and configured as explained in the TF-M getting started.

The additional building materials you can find in the following links:TF-M source folder

Building TF-M (SPE)

This build generates the SPE binary and artifacts, necessary for Building Application (NSPE).

Getting the source code

cd <base folder>
git clone

In this documentation, the cloned trusted-firmware-m repository will be referenced as <TF-M source dir>. Additionally, TF-M depends on several external projects, handled by CMake automatically but you can alter that behaviour using Dependency management.


  • For building with Armclang compiler version 6.10.0+, please follow the note in TF-M getting started.

  • For building with the IAR toolchain, please see the notes in IAR software requirements

  • Please use “/” instead of “\” for paths when running CMAKE commands under Windows Command Prompt.


TF-M has many config options for configuring and fine-tuning. Please check the Configuration section for the details. The base (default) configuration contains only essential components such as SPM and HW platform support hence the only mandatory argument to TF-M build is a platform name, provided via CMake command-line option -DTFM_PLATFORM=<platform name>, it can be:

  • A relative path under <TF-M source dir>/platform/ext/target, for example arm/mps2/an521.

  • An absolute path of target platform, mainly used for out-of-tree platform build.

  • A basename of the target platform folder, for example an521.

Essential Directories

There are 3 essential directories used by CMake for building TF-M:

  • Source code directory <TF-M source dir>

  • Build directory <Build Dir> - the location of all intermediate files required to produce a build target.

  • Install directory <Artifact Dir> - the location of the build output files.


It’s recommended to use absolute paths for all directories. Relative paths may not fully work.


TF-M supports 3 toolchains for cross-compiling and building the project binaries:

  • GNU - default

  • ArmClang

  • IAR

Each toolchain has a configuration file for the compiler and linker. They are located at the root directory of TF-M. Use TFM_TOOLCHAIN_FILE option to provide the absolute path to the preferred toolchain file, or relative path to working directory. The default toolchain_GNUARM.cmake is selected by config_base.cmake file if the option is omitted.

Build type

By default, a MinSizeRel configuration is built. Alternate build types can be specified with the CMAKE_BUILD_TYPE variable. The possible types are:

  • Debug

  • RelWithDebInfo

  • Release

  • MinSizeRel - default

Debug symbols are added by default to all builds, but can be removed from Release and MinSizeRel builds by setting TFM_DEBUG_SYMBOLS to OFF.

RelWithDebInfo, Release and MinSizeRel all have different optimizations turned on and hence will produce smaller, faster code than Debug. MinSizeRel will produce the smallest code and hence is often a good idea on RAM or flash-constrained systems.

Output files

In a successful build, a set of files will be created in the <Artifact Dir>. By default, it is <Build Dir>\api_ns subfolder but you can redirect the output to any location using CMAKE_INSTALL_PREFIX option. It can be an absolute path or relative to your current directory. For the contents of the artifact directory please refer to SPE artifacts structure.

Other build parameters

The full list of default options is in config/config_base.cmake and explained in Build configuration. Several important options are listed below.



Default value


Build level 2 secure bootloader.



User defined header file for TF-M config


Set TFM isolation level.



See TF-M Profiles.

Project Config Header File

CMake variable PROJECT_CONFIG_HEADER_FILE can be set by a user the full path to a configuration header file, which is used to fine-tune component options. The detailed reference for the project config header file is in The Header File Config System.

Building binaries

The command below shows a general template for building TF-M as a typical CMake project:

cmake -S <TF-M source dir> -B <Build Dir> -DTFM_PLATFORM=<platform>
cmake --build <Build Dir> -- install


It is recommended to clean up the build directory before re-build if the config header file is updated. CMake is unable to automatically recognize the dependency when the header file is defined as a macro.

Building default configuration for an521

cd <TF-M source dir>
cmake -S . -B build -DTFM_PLATFORM=arm/mps2/an521
cmake --build build -- install
The command above is intended to do:
  • take TF-M sources in the current . folder

  • build SPE in the build folder

  • for an521 platform

  • using GNU toolchain by default. Use -DTFM_TOOLCHAIN_FILE=<toolchain file> for alternatives as described in Toolchains

  • install output files in build/api_ns folder by default. You can specify a different directory using -DCMAKE_INSTALL_PREFIX=<Artifact dir> as described in Output files


It is recommended to build each different build configuration in a separate build directory.

CMake can generate code for many native build systems. TF-M is tested with Unix Makefiles (default) and Ninja. The -G option can specify alternative generators. For example for building with Ninja in the Debug Build type using ArmClang Toolchains you can use the following:

cd <TF-M source dir>
cmake -S . -B build -DTFM_PLATFORM=arm/mps2/an521 -GNinja -DTFM_TOOLCHAIN_FILE=toolchain_ARMCLANG.cmake -DCMAKE_BUILD_TYPE=Debug
cmake --build build -- install

Dependency management

The TF-M build system will fetch all dependencies by default with appropriate versions and store them inside the build tree. In this case, the build tree location is <build_dir>/lib/ext.

If you have local copies already and wish to avoid having the libraries downloaded every time the build directory is deleted, then the following variables can be set to the paths to the root directories of the local repos. This will disable the automatic downloading for that dependencies and speed up development iterations or allow usage of a dependency version different from the current one. Additionally, these path variables can be set in localrepos.cmake file which will be included in a build if it exists. This file is ignored in TF-M git settings.

The following table lists the commonly used repos. For others, you can refer to lib/ext.


Cmake variable

Git repo URL

Mbed Crypto






The recommended versions of the dependencies are listed in config/config_base.cmake.


  • Some repositories might need patches to allow building it as a part of TF-M. While these patches are being upstreamed they are stored in a dependency folder under lib/ext/. In order to use local repositories those patches shall be applied to original source. An alternative is to copy out the auto-downloaded repos under the <build_dir>/lib/ext. They have been applied with patches and can be used directly.

Example: building TF-M with local Mbed Crypto repo

Preparing a local repository consists of 2 steps: cloning and patching. This is only required to be done once. For dependencies without .patch files in their lib/ext directory the only required step is cloning the repo and checking out the correct branch.

cd <Mbed Crypto base folder>
git clone
cd mbedtls
git checkout <MBEDCRYPTO_VERSION from <TF-M source dir>/config_base.cmake>
git apply <TF-M source dir>/lib/ext/mbedcrypo/*.patch


<Mbed Crypto base folder> does not need to have any fixed position related to the TF-M repo so alternative method to get prepared dependency repos is to let TF-M download it once and then copy them out of the build/lib/ext folder.

Now build TF-M binaries

cd <TF-M source dir>
cmake -S . -B build -DTFM_PLATFORM=arm/mps2/an521 -DMBEDCRYPTO_PATH=<Mbed Crypto base folder>/mbedtls
cmake --build build -- install

Building Application (NSPE)

As a result of Building TF-M (SPE) you will get a set of Output files in <Artifact Dir> required for building TF-M application. Essentially, SPE exports a binary and a set of C source files for PSA interface and platform. Please note that NSPE and SPE are independent projects and can be built using different toolchains and toolchain options.

SPE artifacts structure

SPE components prepared and installed for NSPE usage in <Artifact Dir> will have the following structure:

<Artifact Dir>
├── bin
├── cmake
├── config
├── image_signing
├── interface
├── platform
└── CMakeLists.txt

With certain configurations, additional folders may also be installed. These folders have the following content:

  • bin - binary images of SPE, Bootloader(optional) and combined.

  • cmake - CMake scripts like SPE configuration and NSPE toolchains.

  • config - Configuration files

  • image_signing - binary image signing tool and keys.

  • interface - PSA interface exposed by SPE.

  • platform - source code for a selected hardware platform.

  • CMakeLists.txt - CMake script for the artifacts integration in NSPE.

The content of <Artifact Dir> is an exported directory for integration with CMake projects.


Attempting to change any file in <Artifact Dir> may cause incompatibility issues. Instead, please change the corresponding file in the <TF-M source dir>.

NSPE toolchains

SPE prepares and exports CMake toolchain files for building NSPE in all supported Toolchains in <Artifact Dir>/cmake folder. Toolchain used to build NSPE can be different from what is used to build SPE.

Basic SPE integration

Refer to the example of TF-M applications in tf-m-extras repository.

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