I understand pretty much nothing in your mails :) The problem I was trying to fix below is that linking hwloc plugins on Darwin failed because plugins referred to hwloc-core symbols. Nothing on the libtool command-line said where to find those symbols (I don't understand why it worked on other platforms). I added -lhwloc as a way to tell the linker "those symbols are there". I didn't think it would statically link libhwloc inside the plugins, and it doesn't seem to do so (from what I see in objdump). Is this what you mean?
It's really a problem when linking, not about loading (and scopes that I don't know anything about), but I couldn't test loading before linking worked. Anyway, how should I solve this? Brice Le 05/09/2012 15:58, Jeff Squyres a écrit : > I should clarify... > > In OMPI, if we're building libmpi.so, we default to building plugins as DSOs. > If we're building libmpi.a, then we slurp all the plugins into libmpi.a > (i.e., don't build them as DSOs). This avoids many of the issues in table 2. > > > On Sep 5, 2012, at 9:54 AM, Jeff Squyres wrote: > >> This is a bad idea. >> >> I'm trying to remember the reason why, but we explicitly *removed* such -l >> statements (e.g., removed "-lmpi" from the plugins). Hmm... Oh, right. >> Every time I think I understand linkers, I find out that I don't. So last >> time we had a Big Confusion Discussion About Linkers (BCDAL), I wrote it all >> up: >> >> https://svn.open-mpi.org/trac/ompi/wiki/Linkers >> >> The 4th column in these tables is labeled "OMPI DSO components depend on >> libmpi.so?" (which is somewhat of a misnomer, because not all components are >> at the MPI layer -- so consider it to mean "OMPI DSO components depend on >> some OMPI library, such as libmpi.so?") >> >> The problem cases are #9 and #12 in the first table: i.e., static linking. >> >> Instead, we use lt_dladvise() to open hwloc plugins in the same scope as the >> main application. >> >> Of course, this has its own tradeoffs -- if hwloc itself, is opened as a >> plugin in a private scope, then the plugins won't be able to find the >> symbols it needs (i.e., cases #14, #15, #17, #18, #20, #21, #23, and #24 in >> the 2nd table). >> >> Until POSIX effects hierarchical linker scopes (or at least something like >> "please dlopen this plugin and put it in XYZ linker scope"), there's really >> no good solution here. :-( >> >> >> >> On Sep 5, 2012, at 6:03 AM, <svn-commit-mai...@open-mpi.org> wrote: >> >>> Author: bgoglin (Brice Goglin) >>> Date: 2012-09-05 06:03:52 EDT (Wed, 05 Sep 2012) >>> New Revision: 4815 >>> URL: https://svn.open-mpi.org/trac/hwloc/changeset/4815 >>> >>> Log: >>> Pass -lhwloc to all plugins, at least Darwin wants it >>> (plugins use some hwloc functions) >>> >>> Define a plugins_ldflags with all common stuff for plugins >>> (this somehow reverts r4811) >>> >>> Text files modified: >>> branches/components/src/Makefile.am | 13 +++++++------ >>> >>> 1 files changed, 7 insertions(+), 6 deletions(-) >>> >>> Modified: branches/components/src/Makefile.am >>> ============================================================================== >>> --- branches/components/src/Makefile.am Wed Sep 5 06:03:36 2012 >>> (r4814) >>> +++ branches/components/src/Makefile.am 2012-09-05 06:03:52 EDT (Wed, >>> 05 Sep 2012) (r4815) >>> @@ -21,6 +21,7 @@ >>> >>> pluginsdir = $(libdir)/hwloc >>> plugins_LTLIBRARIES = >>> +plugins_ldflags = -module -avoid-version -lhwloc >>> AM_CPPFLAGS += -DHWLOC_PLUGINS_DIR=\"$(pluginsdir)\" >>> >>> # Sources and ldflags >>> @@ -40,7 +41,6 @@ >>> topology-xml.c \ >>> topology-xml-nolibxml.c >>> ldflags = >>> -common_ldflags = >>> >>> # Conditionally add to the sources and ldflags >>> >>> @@ -52,7 +52,7 @@ >>> xml_libxml_la_SOURCES = topology-xml-libxml.c >>> xml_libxml_la_CPPFLAGS = $(AM_CPPFLAGS) -DHWLOC_BUILD_PLUGIN >>> xml_libxml_la_CFLAGS = $(AM_CFLAGS) $(HWLOC_LIBXML2_CFLAGS) >>> -xml_libxml_la_LDFLAGS = $(common_ldflags) -module -avoid-version >>> $(HWLOC_LIBXML2_LIBS) >>> +xml_libxml_la_LDFLAGS = $(plugins_ldflags) $(HWLOC_LIBXML2_LIBS) >>> endif >>> endif HWLOC_HAVE_LIBXML2 >>> >>> @@ -64,7 +64,7 @@ >>> core_libpci_la_SOURCES = topology-libpci.c >>> core_libpci_la_CPPFLAGS = $(AM_CPPFLAGS) -DHWLOC_BUILD_PLUGIN >>> core_libpci_la_CFLAGS = $(AM_CFLAGS) $(HWLOC_PCI_CFLAGS) >>> -core_libpci_la_LDFLAGS = $(common_ldflags) -module -avoid-version >>> $(HWLOC_PCI_LIBS) >>> +core_libpci_la_LDFLAGS = $(plugins_ldflags) $(HWLOC_PCI_LIBS) >>> endif >>> endif HWLOC_HAVE_LIBPCI >>> >>> @@ -105,7 +105,8 @@ >>> endif HWLOC_HAVE_FREEBSD >>> >>> if HWLOC_HAVE_GCC >>> -common_ldflags += -no-undefined >>> +ldflags += -no-undefined >>> +plugins_ldflags += -no-undefined >>> endif HWLOC_HAVE_GCC >>> >>> if HWLOC_HAVE_WINDOWS >>> @@ -136,7 +137,7 @@ >>> # Installable library >>> >>> libhwloc_la_SOURCES = $(sources) >>> -libhwloc_la_LDFLAGS = $(common_ldflags) $(ldflags) -version-info >>> $(libhwloc_so_version) $(HWLOC_LIBS) >>> +libhwloc_la_LDFLAGS = $(ldflags) -version-info $(libhwloc_so_version) >>> $(HWLOC_LIBS) >>> >>> if HWLOC_HAVE_PLUGINS >>> AM_CPPFLAGS += $(LTDLINCL) >>> @@ -168,5 +169,5 @@ >>> check_LTLIBRARIES = core_fake.la >>> core_fake_la_SOURCES = topology-fake.c >>> core_fake_la_CPPFLAGS = $(AM_CPPFLAGS) -DHWLOC_BUILD_PLUGIN >>> -core_fake_la_LDFLAGS = $(common_ldflags) -module -avoid-version -rpath >>> /nowhere # force libtool to build a shared-library even it's check-only >>> +core_fake_la_LDFLAGS = $(plugins_ldflags) -rpath /nowhere # force libtool >>> to build a shared-library even it's check-only >>> endif >>> _______________________________________________ >>> hwloc-svn mailing list >>> hwloc-...@open-mpi.org >>> http://www.open-mpi.org/mailman/listinfo.cgi/hwloc-svn >> >> -- >> Jeff Squyres >> jsquy...@cisco.com >> For corporate legal information go to: >> http://www.cisco.com/web/about/doing_business/legal/cri/ >> >> >> _______________________________________________ >> hwloc-devel mailing list >> hwloc-de...@open-mpi.org >> http://www.open-mpi.org/mailman/listinfo.cgi/hwloc-devel >
