hwloc (https://www.open-mpi.org/projects/hwloc/) is available under the BSD license. It is hosted as a sub-project of the overall Open MPI project (https://www.open-mpi.org/). Note that hwloc does not require any functionality from Open MPI – it is a wholly separate (and much smaller!) project and code base. It just happens to be hosted as part of the overall Open MPI project.

Basic Installation

Installation is the fairly common GNU-based process:

shell$ ./configure --prefix=...
shell$ make
shell$ make install

The hwloc command-line tool "lstopo" produces human-readable topology maps, as mentioned above. Running the "lstopo" tool is a good way to check as a graphical output whether hwloc properly detected the architecture of your node.

Optional Dependencies

lstopo may also export graphics to the SVG and "fig" file formats. Support for PDF, Postscript, and PNG exporting is provided if the "Cairo" development package (usually cairo-devel or libcairo2-dev) can be found in "lstopo" when hwloc is configured and build.

The hwloc core may also benefit from the following development packages:

libpciaccess for full I/O device discovery (libpciaccess-devel or libpciaccess-dev package). On Linux, PCI discovery may still be performed (without vendor/device names) even if libpciaccess cannot be used.
AMD or NVIDIA OpenCL implementations for OpenCL device discovery.
the NVIDIA CUDA Toolkit for CUDA device discovery. See How do I enable CUDA and select which CUDA version to use?.
the NVIDIA Management Library (NVML) for NVML device discovery. It is included in CUDA since version 8.0. Older NVML releases were available within the NVIDIA GPU Deployment Kit from https://developer.nvidia.com/gpu-deployment-kit .
the NV-CONTROL X extension library (NVCtrl) for NVIDIA display discovery. The relevant development package is usually libXNVCtrl-devel or libxnvctrl-dev. It is also available within nvidia-settings from ftp://download.nvidia.com/XFree86/nvidia-settings/ and https://github.com/NVIDIA/nvidia-settings/ .
the AMD ROCm SMI library for RSMI device discovery. The relevant development package is usually rocm-smi-lib64 or librocm-smi-dev. See How do I enable ROCm SMI and select which version to use?.
the oneAPI Level Zero library. The relevant development package is usually level-zero-dev or level-zero-devel. The implementation must be recent enough to support zesDriverGetDeviceByUuidExp()
libxml2 for full XML import/export support (otherwise, the internal minimalistic parser will only be able to import XML files that were exported by the same hwloc release). See Importing and exporting topologies from/to XML files for details. The relevant development package is usually libxml2-devel or libxml2-dev.
libudev on Linux for easier discovery of OS device information (otherwise hwloc will try to manually parse udev raw files). The relevant development package is usually libudev-devel or libudev-dev.
libtool's ltdl library for dynamic plugin loading if the native dlopen cannot be used. The relevant development package is usually libtool-ltdl-devel or libltdl-dev.

PCI and XML support may be statically built inside the main hwloc library, or as separate dynamically-loaded plugins (see the Components and plugins section).

Also note that if you install supplemental libraries in non-standard locations, hwloc's configure script may not be able to find them without some help. You may need to specify additional CPPFLAGS, LDFLAGS, or PKG_CONFIG_PATH values on the configure command line.

For example, if libpciaccess was installed into /opt/pciaccess, hwloc's configure script may not find it by default. Try adding PKG_CONFIG_PATH to the ./configure command line, like this:

./configure PKG_CONFIG_PATH=/opt/pciaccess/lib/pkgconfig ...

Note that because of the possibility of GPL taint, the pciutils library libpci will not be used (remember that hwloc is BSD-licensed).

Installing from a Git clone

Additionally, the code can be directly cloned from Git:

shell$ git clone https://github.com/open-mpi/hwloc.git
shell$ cd hwloc
shell$ ./autogen.sh

Note that GNU Autoconf >=2.63, Automake >=1.11 and Libtool >=2.2.6 are required when building from a Git clone.

Nightly development snapshots are available on the web site, they can be configured and built without any need for Git or GNU Autotools.