Getting Started

Developing and / or compiling BOLOS applications requires the SDK matching the appropriate device (the Nano S SDK or the Blue SDK) as well as the following two compilers:

  • A standard ARM gcc to build the non-secure (STM32) firmware and link the secure (ST31) applications
  • A standard ARM clang above 4.0.0 with ROPI support to build the secure (ST31) applications

Setting up the Toolchain

The Makefiles used by our BOLOS applications look for the gcc and clang installations using the following process:

  1. If the BOLOS_ENV environment variable is set, then gcc is used from $BOLOS_ENV/gcc-arm-none-eabi-5_3-2016q1/bin/ and clang is used from $BOLOS_ENV/clang-arm-fropi/bin/.
  2. As a fallback, if BOLOS_ENV is not set, then gcc is used from GCCPATH and clang is used from CLANGPATH.
  3. As a fallback, if either GCCPATH or CLANGPATH is not set, then gcc and clang, respectively, are used from the PATH.

This allows you to setup both gcc and clang under the same directory and reference it using BOLOS_ENV, or configure where each compiler is looked for individually. If your system already has an appropriate version of clang installed, you may simply leave BOLOS_ENV and CLANGPATH unset and clang will be used from the PATH (but make sure to set GCCPATH).

If you’re just looking for a one-size-fits-all solution to satisfy your toolchain needs, here are the steps you should follow:

  1. Choose a directory for the BOLOS environment (I’ll use ~/bolos-devenv/) and link the environment variable BOLOS_ENV to this directory.
  2. Download a prebuilt gcc from and unpack it into ~/bolos-devenv/. Make sure there is a directory named bin directly inside ~/bolos-devenv/gcc-arm-none-eabi-5_3-2016q1/.
  3. Download a prebuilt clang from and unpack it into ~/bolos-devenv/. Rename the directory that was inside the archive you downloaded to clang-arm-fropi, or create a link to the directory with that name. Make sure there is a directory named bin directly inside ~/bolos-devenv/clang-arm-fropi/.


Not all of the Makefiles for our applications available on GitHub may recognize BOLOS_ENV in the way described above. If the Makefile is having trouble finding the right compilers, try setting GCCPATH and CLANGPATH explicitly.

Setting up the SDK

Now that you have your toolchain set up, you need to download / clone the SDK for the appropriate Ledger device you’re working with. You can do this anywhere, it doesn’t have to be in your BOLOS_ENV directory (if you even have one). Make sure you checkout the tag matching your firmware version.

Ledger Nano S SDK:

Ledger Blue SDK:

Finally, link the environment variable BOLOS_SDK to the SDK you downloaded. When using the Makefile for our BOLOS apps, the Makefile will use the contents of the SDK to determine your target device ID (Ledger Nano S or Ledger Blue). Even if you aren’t building an app, loading an app with the Makefile still requires you to have the SDK for the appropriate device linked to by BOLOS_SDK.

Python Loader

If you intend to communicate with an actual Ledger device from a host computer at all, you will need the Python loader installed. For more information on installing and using the Python loader, see BOLOS Python Loader. The Makefiles for most of our apps interface with the Python loader directly, so if you only need to load / delete apps then you don’t need to know how to use the various scripts provided by the Python loader, but you’ll still need it installed.

Building and Loading Apps

In this section, we’ll walk you through compiling and loading your first BOLOS app onto your device. Applications that support multiple BOLOS devices are typically contained within a single repository, so you can use the same repository to build an app for different Ledger devices. Just make sure that you’ve set BOLOS_SDK to the appropriate SDK for the device you’re using. The Makefiles used by our apps use the contents of the SDK to determine which device you’re using.

Firstly, download the app and make sure to checkout a version of the application that is compatible with your SDK version. (We’ll do our best to keep the sample apps updated to the latest SDK version.)

git clone

Now you can let the Makefile do all the work. The load target will build the app if necessary and load it onto your device over USB.

cd blue-sample-apps/blue-app-helloworld/
make load

And you’re done! After confirming the installation on your device, you should see an app named “Hello World”. The app can be deleted like so:

make delete