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lfoss/2025b now available in the EESSI RISC-V stack

The EESSI RISC-V software stack available through the dev.eessi.io/riscv repository now includes the lfoss/2025b toolchain.

This is an important milestone for the RISC-V enablement work in EESSI, since it brings a modern LLVM-based software toolchain to the growing collection of software available for RISC-V systems through EESSI.

The RISC-V software stack is distributed through the EESSI development repository infrastructure and is intended for experimentation, testing, and early adoption of RISC-V support in EESSI.

What is lfoss

lfoss is the LLVM-based counterpart to the widely used foss toolchain in EESSI and EasyBuild ecosystems.

Where foss is centered around GCC, the lfoss family uses LLVM/Clang while still providing the familiar scientific software stack components such as MPI, BLAS/LAPACK, FFT libraries, and related HPC tooling.

The availability of lfoss/2025b on RISC-V is particularly relevant because LLVM's RISC-V backend has matured significantly in recent years, making it increasingly viable for HPC and scientific computing workloads.

Why this matters

Adding lfoss/2025b to the EESSI RISC-V stack provides several benefits:

  • access to a modern LLVM/Clang-based compiler environment on RISC-V;
  • broader compiler coverage for portability testing;
  • improved support for projects already using LLVM toolchains;
  • additional opportunities to validate and improve RISC-V support in HPC software ecosystems.

This also helps align the RISC-V stack more closely with the software offerings already available on x86_64 and AArch64 platforms in EESSI.

Accessing the RISC-V stack

The RISC-V stack is currently provided through the dedicated RISC-V development repository. To access it, make sure that the software.eessi.io and dev.eessi.io CernVM-FS repositories are available on your system, and then just run:

$ export EESSI_VERSION_OVERRIDE=2025.06-001
$ source /cvmfs/software.eessi.io/versions/2025.06/init/lmod/bash
This EESSI production version only provides a RISC-V compatibility layer,
software installations are provided by the EESSI development repository at /cvmfs/dev.eessi.io/riscv.

Module for EESSI/2025.06 loaded successfully
EESSI has selected riscv64/generic as the compatible CPU target for EESSI/2025.06
EESSI did not identify an accelerator on the system
(for debug information when loading the EESSI module, set the environment variable EESSI_MODULE_DEBUG_INIT)

On a RISC-V system, this will initialize the RISC-V software stack environment.

You can then verify that the new toolchain is available:

module avail lfoss

and load it via:

module load lfoss/2025b

Availability in dev.eessi.io/riscv

The RISC-V stack is currently hosted in the EESSI development infrastructure, which is intended for pre-release and experimental software deployments.

As with the rest of the RISC-V repository:

  • software availability is still evolving;
  • builds may be updated or replaced;
  • the stack currently focuses on generic RISC-V targets.

The RISC-V repository already contains a growing collection of scientific software and toolchains.

Looking ahead

The addition of lfoss/2025b is another step toward broader and more mature RISC-V support within EESSI.

Future work will include:

  • expanding software coverage built with LLVM-based toolchains;
  • improving validation and CI coverage for RISC-V;
  • enabling additional optimized RISC-V targets as the ecosystem matures;
  • continuing collaboration with the broader RISC-V and HPC communities.

RISC-V remains an exciting and rapidly developing architecture for HPC and scientific computing, and EESSI aims to make portable, reproducible software stacks readily available for emerging platforms.

Learn more