Hi Matt, Thanks for posting config.log​. I found the issue. Both mpich the library and hydra the program uses hwloc and independently tries to probe hwloc. Because hydra is configured as a subdir inside mpich configure, it inherits the CFLAGS from mpich, resulting in using embedded hwloc.h​ while linking with external libhwloc​. We'll patch mpich to strengthen its config check. Meanwhile, you can pass --with-hwloc=embedded​ to the mpich configure to force both mpich and hydra to use embedded hwloc, which should bypass your issue. Thanks for reporting! -- Hui Zhou ________________________________ From: Thompson, Matt (GSFC-610.1)[SCIENCE SYSTEMS AND APPLICATIONS INC] <[email protected]> Sent: Wednesday, December 15, 2021 7:13 AM To: [email protected] <[email protected]> Cc: Zhou, Hui <[email protected]> Subject: Re: [EXTERNAL] Re: [mpich-discuss] Help Building MPICH 4.0b1: undefined references to hwloc Hui, Please find attached the requested config.log Matt -- Matt Thompson, SSAI, Ld Scientific Programmer/Analyst NASA GSFC, Global Modeling and Assimilation Office Code 610.1, 8800 Greenbelt Rd, Greenbelt, MD 20771 Phone: 301-614-6712 Fax: 301-614-6246 http://science.gsfc.nasa.gov/sed/bio/matthew.thompson From: "Zhou, Hui via discuss" <[email protected]> Reply-To: "[email protected]" <[email protected]> Date: Tuesday, December 14, 2021 at 6:14 PM To: "[email protected]" <[email protected]> Cc: "Zhou, Hui" <[email protected]> Subject: [EXTERNAL] Re: [mpich-discuss] Help Building MPICH 4.0b1: undefined references to hwloc Hi Matt, Could post your src/pm/hydra/config.log​? -- Hui Zhou ________________________________ From: Thompson, Matt (GSFC-610.1)[SCIENCE SYSTEMS AND APPLICATIONS INC] via discuss <[email protected]> Sent: Tuesday, December 14, 2021 2:40 PM To: [email protected] <[email protected]> Cc: Thompson, Matt (GSFC-610.1)[SCIENCE SYSTEMS AND APPLICATIONS INC] <[email protected]> Subject: [mpich-discuss] Help Building MPICH 4.0b1: undefined references to hwloc MPICH Discuss, I'm sure I've done something stupid, but I'm not sure what. I tried searching google, but my google-fu failed me. Today I decided to try and build MPICH 4.0b1 on a cluster I'm on (NCCS Discover) using GCC 11.2. My configure line was quite boring: ./configure CC=gcc CXX=g++ FC=gfortran \ FCFLAGS=-fallow-argument-mismatch \ FFLAGS=-fallow-argument-mismatch \ --prefix=/discover/swdev/gmao_SIteam/MPI/mpich/4.0b1/gcc-11.2.0 The MPICH configure step was nice enough to let me know I needed those FFLAGS and FCFLAGS. And it configured just happily.[1] When I went to the make step I eventually it errored out with: make[3]: Entering directory '/gpfsm/dswdev/gmao_SIteam/MPI/src/mpich-4.0b1/src/pm/hydra' CCLD libpm.la CCLD hydra_persist /usr/bin/ld: /discover/swdev/gmao_SIteam/MPI/src/mpich-4.0b1/src/pm/hydra/.libs/libhydra.a(topo_hwloc.o): in function `HYDT_topo_hwloc_init': /discover/swdev/gmao_SIteam/MPI/src/mpich-4.0b1/src/pm/hydra/tools/topo/hwloc/topo_hwloc.c:577: undefined reference to `hwloc_topology_set_io_types_filter' collect2: error: ld returned 1 exit status Makefile:1286: recipe for target 'hydra_persist' failed make[3]: *** [hydra_persist] Error 1 Now, as far as I can tell from the configure output, I'm using the embedded hwloc: checking if hwloc meets minimum version requirement... no configure: ===== configuring modules/hwloc ===== ... ### Configuring hwloc core ### checking hwloc building mode... embedded configure: hwloc builddir: /discover/swdev/gmao_SIteam/MPI/src/mpich-4.0b1/modules/hwloc configure: hwloc srcdir: /discover/swdev/gmao_SIteam/MPI/src/mpich-4.0b1/modules/hwloc ... And I can't see anything in the output that it's somehow picking up on an hwloc I might have installed somewhere else (be it Open MPI or just hwloc by hand). Maybe there are flags I need to pass? I do see reference to --with-hwloc=embedded, but it looks like configure decided to use that itself. Thanks for any help, Matt [1] Note: I'm building on an Infiniband system so maybe I need to do a build with --with-device=ch4:ucx eventually, but that's a runtime thing. I figure it can't be involved with this error...right? -- Matt Thompson, SSAI, Ld Scientific Programmer/Analyst NASA GSFC, Global Modeling and Assimilation Office Code 610.1, 8800 Greenbelt Rd, Greenbelt, MD 20771 Phone: 301-614-6712 Fax: 301-614-6246 http://science.gsfc.nasa.gov/sed/bio/matthew.thompson