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Subject: [hwloc-users] Patch to disable GCC __builtin_ operations
From: Josh Hursey (jjhursey_at_[hidden])
Date: 2011-06-08 16:28:04

(This should have gone to the devel list)

The attached patch adds a configure option (--disable-gcc-builtin) to
disable the use of GCC __builtin_ operations, even if the GCC compiler
supports them. The patch is a diff from the r3509 revision of the
hwloc trunk.

I hit a problem when installing hwloc statically on a machine with a
slightly different gcc support libraries and OSs on the head/compile
node versus the compute nodes. The builtin functions would cause hwloc
to segfault when run on the compute nodes. By disabling the builtin
operations, and using the more portable techniques seemed to do the

This problem first became apparent when using hwloc as part of Open
MPI. In Open MPI the mpirun process runs on the headnode, so the hwloc
install would work in the mpirun process but cause the compute
processes to segv.

Can you review the patch, and apply it to the trunk? Once the patch is
in the trunk, then I'll work on the Open MPI folks to update their


Joshua Hursey
Postdoctoral Research Associate
Oak Ridge National Laboratory