Telcon: 2026 04 08 - spack/spack GitHub Wiki

Wednesday April 8th, 9am PT (UTC -7:00)

Invite Link: https://zoom.us/j/93354081914?pwd=kkovIeyqQPkb9KgQUKKgOnV3kWafS0.1

Attendees

Peter Scheibel (host)
Diego Menéndez
Asher Antao
Brad Richardson
Ajay Panyala

Agenda

This is for Q&A: there are currently no pre-planned topics

Asher: CMake issue (building cmake itself)
- If I target zen5
  - Unsure if this is all CMake-based packages
  - Using [email protected]
  - Error: C++ compiler does not support c++11
  - Perhaps caused by earlier warning: g++: warning: '-mcpu=' is deprecated; use '-mtune=' or '-march=' instead
- If I leave target unset, it chooses x86_64 and that passes
- Separately: Spack is not detecting a system as zen5 (because a flag was removed)
  - (This was addressed locally by patching Spack)
- Peter: can you set a generic target for just cmake
- Side issue, had to set an external for knem
- Peter: I should figure out what -march/-mcpu-style flags Spack inserts
  - Asher: brought up and grep'ed through archspec
Asher: I have pipeline doing builds in Jacamar
- Once build finishes, results are dumped into a buildcache
- I use --padded-length parameter
- This adds a bunch of dummy info to path
- When I push it to binary cache
- Then another node has write access to software dirs
  - it reads from binary cache, and installs it into a location for people to use
- Someone brought to my notice: they run mpicc -show, and there are a bunch of / in paths reported by that (i.e. the filler characters in expanded binary caches show up there)
Ajay: openmpi/ucx issues
- building openmpi w/spack but pmix, ucx external works
- if I try to build GPU-enabled ucx, there is a problem
- nvshmem requires ucx with CUDA support
- may try to build ucx with cuda support outside of spack
- Peter: it would be useful if you could open an issue for whatever issues you are seeing with the spack build of ucx (with or without cuda) and if you get a successful build of ucx with cuda outside of spack, it would be useful to see the options you add
- Ajay: found a slack thread on ucx+cuda
  - https://spackpm.slack.com/archives/C08Q62S7XEX/p1773854423962919
Ajay: compiler_mixing - is it off by default
- Peter: compiler mixing is allowed by default
- Ajay: does compiler mixing setting apply to externals?
  - Peter: yes (if you have a compiler specified on an external, and compiler_mixing: false, then Spack will force the compiler on the external to match the dependent)
    - You can get around that by specifying compiler_mixing: [list of external package names]
Ajay: modules don't have LD_LIBRARY_PATH set
- If everything is installed w/Spack, they do specify LD_LIBRARY_PATH
- once externals are involved, the modules are missing LD_LIBRARY_PATH
- Asher: I had to modify modules.yaml to add prefix inspections (as described in https://spack.readthedocs.io/en/latest/module_file_support.html#the-modules-yaml-config-file-and-module-sets)

# this is in modules.yaml
prefix_inspections:
./include:
- CPATH
./lib:
- LIBRARY_PATH
- LD_LIBRARY_PATH
./lib64:
- LIBRARY_PATH
- LD_LIBRARY_PATH
./bin:

Diego: reported LIGGGHTS depending on VTK versions from 6.1.0 to 8.2.0, all deprecated (issue #4171)
- was able to manually-install LIGGGHTS after editing its Makefile.user with Spack0.23-installed VTK 9.3 in the past
- having issues to install VTK with Spack 1.1.1 due to opengl placeholder dependency (mesa+opengl, glx, gl2ps), not sure how to proceed after error
- RPMs such as libglvnd-devel provide headers and library files mentioned in OpenGL's package.py and the following error, but am not being able to add them with spack external find opengl on RHEL 8.

==> Error: Failed to install opengl due to InstallError: This package is intended to be a placeholder for
        system-provided OpenGL libraries from hardware vendors.  Please
        download and install OpenGL drivers/libraries for your graphics
        hardware separately, and then set that up as an external package.
        An example of a working packages.yaml:

        packages:
          opengl:
            buildable: False
            externals:
            - spec: [email protected]
              prefix: /opt/opengl

        In that case, /opt/opengl/ should contain these two folders:

        include/GL/       (opengl headers, including "gl.h")
        lib               (opengl libraries, including "libGL.so")

Using prefix: /usr allowed building mesa+opengl and its dependent packages to complete the installation of VTK 9.5.1. Now, only the LIGGGHTS dependencies to newer VTK versions need to be fixed on the opened issue for the complete installation to be done using Spack. Thank you so much!