I hit an error while trying to build mvapich2-1.9a2 which I can reproduce with mpich2-1.5b2. When I try configuring mpich2 or mvapich2 hwloc isnt configured properly and configure ends up detecting the sizes incorrectly which results in a build failure when compiling. I reported this issue with mvapich2 mailing list[1]. The error I am noticing for mpich2-1.5b2 is as follows: ### ### Configuring hwloc core ### checking hwloc building mode... embedded configure: hwloc builddir: /home/bramesh/ARC/apps/build/mpich2-1.5b2/src/pm/hydra/tools/topo/hwloc/hwloc configure: hwloc srcdir: /home/bramesh/ARC/apps/build/mpich2-1.5b2/src/pm/hydra/tools/topo/hwloc/hwloc checking if want hwloc maintainer support... disabled (embedded mode) checking for hwloc directory prefix... tools/topo/hwloc/hwloc/ checking for hwloc symbol prefix... hwloc_ checking size of void *... 0 checking which OS support to include... Linux checking which CPU support to include... unknown -- assuming x86_64 checking size of unsigned long... (cached) 8 checking size of unsigned int... 0 checking for the C compiler vendor... gnu configure line: ./configure --prefix=/home/bramesh/apps/mpich2 --enable-shared --with-pbs=/opt/torque/torque The error I am noticing for mvapich2 is as follows: ### ### Configuring hwloc core ### checking hwloc building mode... embedded configure: hwloc builddir: /home/bramesh/ARC/apps/build/mvapich2-1.9a2/src/pm/hydra/tools/topo/hwloc/hwloc configure: hwloc srcdir: /home/bramesh/ARC/apps/build/mvapich2-1.9a2/src/pm/hydra/tools/topo/hwloc/hwloc checking if want hwloc maintainer support... disabled (embedded mode) checking for hwloc directory prefix... tools/topo/hwloc/hwloc/ checking for hwloc symbol prefix... hwloc_ checking size of void *... 0 checking which OS support to include... Linux checking which CPU support to include... unknown -- assuming x86_64 checking size of unsigned long... (cached) 8 checking size of unsigned int... 0 checking for the C compiler vendor... gnu configure line: ./configure --prefix=$HOME/apps/mvapich2 --enable-shared --with-ib-include=/opt/ofed/ofed/include --with-ib-libpath=/opt/ofed/ofed/lib64 --with-pbs=/opt/torque/torque If I built hwloc-1.5 or hwloc-1.6 separately in embedded mode I dont see the error. I was wondering what is the way to fix this issue so that I can build mvapich2 to use in our IB cluster. I am not subscribed to the list so would appreciate it if I am copied on the replies. [1] http://mail.cse.ohio-state.edu/pipermail/mvapich-discuss/2013-January/004209... -- Bharath