ATLAS Externals Repository

This repository holds the code for building all flavours of ATLAS "externals" projects. Projects holding code not developed by ATLAS, but used by the offline/simulation/analysis software of the experiment.

Code In The Repository

The main project configurations can be found in the Projects directory. You need to point CMake to one of those folders to build one of the specific externals projects.

Other directories hold packages that either build, or set up some external software to be used by downstream projects.

Build / Install

The projects can be built in a fairly standard way. The AnalysisBaseExternals project should be possible to build on practically any POSIX platform that supports C++20. All the other projects on the other hand need to be built on some platform for which an LCG release is available.

You are highly recommended to use an out-of-source build for all projects, even though in-source builds may also work. But they are generally not supported/tested.

The most common build procedure is:

asetup ...
cmake -DCMAKE_BUILD_TYPE=Release -DCTEST_USE_LAUNCHERS=TRUE \
   -S atlasexternals/Projects/AthenaExternals -B build
cmake --build build/
DESTDIR=/some/location cmake --install build/

N.B.

• At the time of writing our production platform is x86_64-el9-gcc13, so you would execute the following to get a functional build environment

asetup none,gcc13,cmakesetup --cmakeversion=3.30.5

• You may need to ask for a specific CMake version explicitly. At the time of writing, you would need to use CMake 3.30.5;
• See AtlasSetupReference for a lot more details about asetup.

Version

This branch of the repository is meant to serve as a basis for the builds of the various projects of the atlas/athena repository's main branch.