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Common toolchains

This page documents the concept of common toolchains in the EasyBuild community; for a more general definition of what (compiler) toolchains are, see Toolchains.

Definition and motivation

Picking a compiler toolchain to use is one of the first things you (need to) do when starting to use EasyBuild. This can be a daunting task, since a whole bunch of toolchains and different toolchain versions are readily available in EasyBuild. It may be difficult to determine which toolchain would be most rewarding to use, in terms of stability, performance of the resulting binaries and readily available easyconfig files.

In an attempt to focus the effort of the EasyBuild community, the concept of so-called common toolchains was introduced.

The idea is to compose and maintain a limited set of specific compiler toolchains, and try and convince many HPC sites to employ these toolchains. This helps in assuring stability of these toolchains w.r.t. which software can be built (correctly) with them, since they get significantly more testing. In addition, the expectation/hope is that more easyconfigs are contributed back to the central easyconfigs repository (, resulting in a wide range of readily available easyconfig files using the common toolchains.

The intention is to revise/update the definitions of the common toolchains regularly (see Update cycle for common toolchains), which again can be a joint effort that benefits many HPC sites.

Currently, two different families of common toolchains are being maintained: foss and intel; see below for more details, and also Overview of common toolchains.

Toolchain diagram

To be more helpful in understanding the differences between these families, here is a diagram that explains what is added in each additional layer.

Note: because there have been a few changes in toolchains, there are notes below the diagram that explain the differences between the generations going back to the 2020b version of the foss and intel toolchains.

Newest generations (2022b and later):

graph LR
  A[GCCcore] --> |binutils| B[GCC];
  A --> |binutils| C[intel-compilers];
  B --> |OpenMPI| E[gompi];
  C --> |impi| F[iimpi];
  B --> |"FlexiBLAS (incl. LAPACK) + FFTW"| D[gfbf];
  D --> |OpenMPI + ScaLAPACK| G[foss];
  E --> |FlexiBLAS + FFTW + ScaLAPACK| G[foss];
  F --> |imkl| Z[intel];
  C --> |imkl| H[iimkl];
  H --> |impi| Z[intel];

Note: following notes apply for the generations listed and those older than it:

  • 2022a - iimkl not present yet
  • 2021b - gfbf not present yet
  • 2020b - foss uses OpenBLAS instead of FlexiBLAS, iccifort is used instead of intel-compilers

Keep in mind that when creating an Easyconfig, you need to look at what toolchain "level" (e.g. foss vs GCC) your dependencies are using and choose the highest of them (or higher if needed) for your easyconfig. For example, if one of your dependencies is using the foss toolchain, you need to use the foss toolchain, and not the GCC toolchain.

foss toolchain

The foss common compiler toolchain consists entirely of open source software (hence the name, derived from the common term 'FOSS', which is short for "Free and Open Source Software").

This toolchain consists of:


The toolchain name was deliberately chosen to be generic, to allow for swapping any of the toolchain components with a better (open source) alternative in the future, should the need or opportunity arise.

intel toolchain

The intel common compiler toolchain consists of the Intel compilers and libraries, i.e.:


This compiler toolchain includes licensed software; valid licenses must be available to install and use it.

Versioning scheme for common toolchains

The common toolchains follow a specific versioning scheme, which takes the 6-month update cycle into account.

Each revision of the common toolchains is versioned as the year in which it was defined, plus an additional 'a' or 'b' to indicate whether the toolchain was defined at the start of the year ('a') or halfway through the year ('b'); in short, the common toolchains are versioned as <year>{a,b}.

For example, foss/2021b is a revision of the foss that was composed mid-2021.

A full historic overview of the foss and intel common toolchains is available in Overview of common toolchains.


Next to the versions that follow the <year>{a,b} versioning scheme, additional versions of the foss and intel versions are available as well.

These versions are not considered to be part of the series of common toolchains (even though they consists of the same toolchain components). These versions may be site-specific, or compositions that were put in place to evaluate a potential future common toolchain.

Typically, they are versioned as <year>.<month>, indicating when the most recent component included was released, or when that particular toolchain composition was defined.

Update cycle for common toolchains

The intention is to revise and update the common toolchains every 6 months: once in late December/early January (version <year>a), and once in late June/early July (version <year>b).

This is meant be to be a community effort, in the sense that a proposal for an updated composition is shared and discussed before it is set in stone.

Recent versions of each of the toolchain components are considered, taking into account stability, performance improvements, added features, known bugs/issues and experiences with those versions.

Moreover, the proposed toolchain compositions are tested extensively, typically by rebuilding all available easyconfigs that are using the most recent revision of the common toolchains at that time.

Overview of common toolchains

Component versions in foss toolchain

foss date binutils GCC Open MPI FlexiBLAS OpenBLAS LAPACK ScaLAPACK FFTW
2021a May '21 2.36.1 10.3.0 4.1.1 3.0.4 0.3.15 (incl. with FlexiBLAS) 2.1.0 3.3.9
2021b Oct '21 2.37 11.2.0 4.1.1 3.0.4 0.3.18 (incl. with FlexiBLAS) 2.1.0 3.3.10
2022a Jun '22 2.38 11.3.0 4.1.4 3.2.0 0.3.20 (incl. with FlexiBLAS) 2.2.0 3.3.10
2022b Dec '22 2.39 12.2.0 4.1.4 3.2.1 0.3.21 (incl. with FlexiBLAS) 2.2.0 3.3.10
2023a Jun '23 2.40 12.3.0 4.1.5 3.3.1 0.3.23 (incl. with FlexiBLAS) 2.2.0 3.3.10
2023b Dec '23 2.40 13.2.0 4.1.6 3.3.1 0.3.24 (incl. with FlexiBLAS) 2.2.0 3.3.10

Component versions in intel toolchain

intel date binutils GCC Intel compilers Intel MPI Intel MKL
2021a May '21 2.36.1 10.3.0 2021.2.0 2021.2.0 2021.2.0
2021b Oct '21 2.37 11.2.0 2021.4.0 2021.4.0 2021.4.0
2022a Jun '22 2.38 11.3.0 2022.1.0 2021.6.0 2022.1.0
2022b Dec '22 2.39 12.2.0 2022.2.1 2021.7.1 2022.2.1
2023a Jun '23 2.40 12.3.0 2023.1.0 2021.9.1 2023.1.0
2023b Dec '23 2.40 13.2.0 2023.2.1 2021.10.1 2023.2.0

Overview of common toolchains (deprecated versions)

Component versions in foss toolchain (deprecated versions)

foss date binutils GCC Open MPI FlexiBLAS OpenBLAS LAPACK ScaLAPACK FFTW
2014b Jul '14 '(none) 4.8.3 1.8.1 (none) 0.2.9 3.5.0 2.0.2 3.3.4
2015a Jan '15 '(none) 4.9.2 1.8.4 (none) 0.2.13 3.5.0 2.0.2 3.3.4
2015b Jul '15 2.25 4.9.3 1.8.8 (none) 0.2.14 3.5.0 2.0.2 3.3.4
2016a Jan '16 2.25 4.9.3 1.10.2 (none) 0.2.15 3.6.0 2.0.2 3.3.4
2016b Jul '16 2.26 5.4.0 1.10.3 (none) 0.2.18 3.6.1 2.0.2 3.3.4
2017a Jan '17 2.27 6.3.0 2.0.2 (none) 0.2.19 3.7.0 2.0.2 3.3.6(-pl2)
2017b Jul '17 2.28 6.4.0 2.1.1 (none) 0.2.20* (incl. with OpenBLAS) 2.0.2 3.3.6(-pl2)
2018a Jan '18 2.28 6.4.0 2.1.2 (none) 0.2.20* (incl. with OpenBLAS) 2.0.2 3.3.7
2018b Jul '18 2.30 7.3.0 3.1.1 (none) 0.3.1 (incl. with OpenBLAS) 2.0.2 3.3.8
2019a Jan '19 2.31.1 8.2.0 3.1.3 (none) 0.3.5 (incl. with OpenBLAS) 2.0.2 3.3.8
2019b Sept '19 2.32 8.3.0 3.1.4 (none) 0.3.7 (incl. with OpenBLAS) 2.0.2 3.3.8
2020a May '20 2.34 9.3.0 4.0.3 (none) 0.3.9 (incl. with OpenBLAS) 2.1.0 3.3.8
2020b Nov '20 2.35 10.2.0 4.0.5 (none) 0.3.12 (incl. with OpenBLAS) 2.1.0 3.3.8

(components marked with * were patched)

Component versions in intel toolchain (deprecated versions)

intel date binutils GCC Intel compilers Intel MPI Intel MKL
2014b Jul '14 '(none) 4.8.3 2013.5.192
2015a Jan '15 '(none) 4.9.2 2015.1.133
2015b Jul '15 2.25 4.9.3 2015.3.187
2016a Jan '16 2.26 4.9.3 2016.1.150
2016b Jul '16 2.26 5.4.0 2016.3.210
2017a Jan '17 2.27 6.3.0 2017.1.132 2017.1.132 2017.1.132
2017b Jul '17 2.28 6.4.0 2017.4.196 2017.3.196 2017.3.196
2018a Jan '18 2.28 6.4.0 2018.1.163 2018.1.163 2018.1.163
2018b Jul '18 2.30 7.3.0 2018.3.222 2018.3.222 2018.3.222
2019a Jan '19 2.31.1 8.2.0 2019.1.144 2018.4.274 2019.1.144
2019b Sept '19 2.32 8.3.0 2019.5.281 2018.5.288 2019.5.281
2020a May '20 2.34 9.3.0 2020.1.217 2019.7.217 2020.1.217
2020b Nov '20 2.35 10.2.0 2020.4.304 2019.9.304 2020.4.304

Customizing common toolchains

Sometimes the need arises to customize one or more components of a common toolchain w.r.t. site-specific aspects. One common example is using additional configuration options for Open MPI.

To customize a toolchain component, you should copy the corresponding easyconfig file, modify according to your needs, and make sure it is included in a location in the robot search path that precedes the location of the easyconfig files that are included with EasyBuild (see also Searching for easyconfigs: the robot search path), before building and installation the toolchain.

More information about toolchains

Please see the List of known toolchains for how to obtain a listing of the currently known toolchains.

For a detailed listing of the compiler options available with each toolchain, please see Available toolchain options (by toolchain).