An elaborated environment for building binary xPacks.

The xPack Build Box is an elaborated build environment focused on obtaining reproducible builds while building cross-platform standalone binaries for GNU/Linux, macOS and Windows.

How it works?

XBB achieves repeatability and consistency by compiling all dependencies from sources.

This applies both to the development environment and to the final application binaries.

By strictly controlling the versions of the compiled sources and tools, it is possible to create build environments that use about the same tools on both GNU/Linux (Intel and Arm) and macOS, helping to obtain consistent results.

On GNU/Linux, to allow the builds to run on any distribution, the actual development tools are packed as Docker images (Intel/Arm, 32/64-bit).

Types of builds

There are two types of builds:

  • local/native builds, intended for development and running on the local machine
  • distribution builds, intended for xPack binary distributions and running on most modern machines

The main use cases of XBBs are distribution builds, but they can be used for native builds as well.

Supported platforms

Generally, xPack binaries are available for the following platforms:

  • Windows Intel 64-bit
  • GNU/Linux Intel 64-bit
  • GNU/Linux Arm 32-bit
  • GNU/Linux Arm 64-bit
  • macOS Intel 64-bit
  • macOS Apple Silicon 64-bit

XBB supports creating binaries for all these platforms.

For the detailed supported versions, please check the specific release page.

GNU/Linux Arm binaries

Support for Arm binaries was added in v3.1, in early 2020.

The supported architectures are:

  • arm64v8 - the ARMv8 64-bit architecture Aarch64
  • arm32v7 - the ARMv7 32-bit architecture with hardware float (armhf)

macOS Apple Silicon

Support for Apple Silicon was added in v3.4, in late 2021.

Docker specifics

As with any Docker builds, the XBB builds run completely inside Docker containers, which start afresh each time they are instantiated.

To pass the folder with the build scripts in and the results out, it is usual to use a Work folder, for example:

$ docker run -it --volume "${HOME}/Work:/Host/Work" ilegeul/ubuntu:amd64-18.04-xbb-v3.4
root@831bc35faf9f:/# ls -l /Host/Work
total 175320
drwxr-xr-x  14 root root       448 Mar  7 19:47 arm-none-eabi-gcc-9.2.1-1.2
drwxr-xr-x 144 root root      4608 Mar  9 13:15 cache
drwxr-xr-x  34 root root      1088 Mar 26 11:22 openocd-0.10.0-14
drwxr-xr-x  12 root root       384 Oct 30 19:00 riscv-none-embed-gcc-8.3.0-1.1

In this simple configuration, the builds run with root permissions; with more elaborate configurations it is possible to start the Docker images with user rights, but they are beyond the scope of this document.

How to use the XBB tools

Both on GNU/Linux and macOS, the XBB tools are installed in separate folders, and are fully distinct from the system tools.

To access them, the application should update the PATH to prefer the newer XBB tools.

Scripts defining some helper functions are available.


The xbb_activate function can be called either for the entire lifespan of the script, or, for a better isolation, in inner shells when the new tools are really needed.

source "/opt/xbb/"



For macOS the recommended use case is similar, except the XBB tools are installed in the user HOME folder:

source "${HOME}/.local/xbb/"


The script

The build environment includes a helper script,, which should be included with source by the build scripts, to define more bash functions to the shell.

These functions are used to extend the environment with resources available in the XBB folders.

The xbb_activate function is used to extend the PATH with folders in the XBB folders, in front of existing folders, so that the XBB executables are preferred over the system ones.

The pkg-config-verbose script

While running the configuration step, it is sometimes useful to trace how pkg-config identifies resources to be used during the build.

The standard pkg-config does not have an option to increase verbosity.

The workaround is to use a separate script that displays the received command and the response on the stderr stream.

This script is not specific to XBB, and can be used with any build.

For this, copy the file into .../xbb/bin or any other folder present in the PATH and pass the script name via the environment.

chmod +x /opt/xbb/bin/pkg-config-verbose
export PKG_CONFIG=pkg-config-verbose


All images include the TeX tools; on GNU/Linux, they are installed either in the system folders or in a custom global folder (like /opt/texlive); on on macOS they are installed in a custom local folder (like ${HOME}/.local/texlive).

Maintainer info

Future plans

The current XBB got extremely complex due to the initial requirement to also support RedHat Enterprise systems.

RedHat maintenance support 1 for RHEL 7 ended in Aug. 2020, with maintenance support 2 to last until June. 2024. However XBB support for RHEL 7 is a tough requirement, and was discontinued starting with 2022.

Compatibility was moved up to Ubuntu 18 (GLIBC 2.27). This also provides compatibility with RedHat 8 / Debian 10, which both use GLIBC 2.28.


The xPack Build Box is inspired by the Holy Build Box.

Comments on the content of this page that might be useful for other readers are welcomed here. For question and general support, please use GitHub Discussions.