On Wednesday 21 July 2010 03:49:42 Simon Horman wrote: > On Tue, Jul 20, 2010 at 05:35:01PM +0200, Ultrabug wrote: > > ----- Original Message ----- > > From: Simon Horman <ho...@verge.net.au> > > To: The Pacemaker cluster resource manager > > <pacemaker@oss.clusterlabs.org> Sent: Tue, 20 Jul 2010 05:10:32 +0200 > > (CEST) > > Subject: Re: [Pacemaker] Proposing patch for ld --as-needed > > > > On Sat, Jul 17, 2010 at 01:12:20PM +0200, Ultrabug wrote: > > >Dear list, > > > > > >I would like to ask you about a possible upstream modification regarding > > >the -- as-needed ld flag for which we Gentoo users need to patch the > > >pacemaker sources to get it compile. > > > > > >I'm attaching the patch which, as you can see, is relatively small and > > >simple (looks to me at least). The question is whether or not you think > > >this could be done upstream ? > > > > > >Thank you for your interest in this and all you work, > > > > Out of interest, could you explain why this is needed? > > Is it because gold is being used as the linker? > > [ please don't top-post ]
[ noticed after sending, sorry ] > > Thanks for the link. > > I guess what is happening without --as-needed is that the curses > library is being dragged in somewhere, somehow - without your proposed > change CURSESLIBS is used exactly nowhere. > Actually the two chunks of the patch have different purposes. The first one is needed because the linking order has a meaning on a as-needed system and libpengine uses functions that are defined in libpe_status. Here is an example of failing build : http://paste.pocoo.org/show/239905/ If you try to compile a program that uses libpengine that doesn't need libpe_status, e.g. gcc -Wl,--as-needed ptest.c -o ptest -lpe_status -lpengine (shortened version of actual linking from pacemaker build.log) linking will fail. Linker evaluates that statement sequentially starting from the inner most lib: 1) do I need libpe_status? No, forget about it. 2) do I need libpengine? Yes, please. 3) is everything all right? Ups, I don't know what `was_processing_warning' is, die... The second one explicitly adds CURSESLIBS dependency to libpe_status. If pacemaker detects ncurses, you get HAVE_NCURSES_H and e.g. status_print (used in lib/pengine/native.c etc.) becomes wrapper around "printw" (see configure.ac). You need to provide `printw' or any linking with libpe_status will fail. Fail build example : http://paste.pocoo.org/show/239916/ > So I think that your change is a step in the right direction, > though for completeness I think that you also need to give the same > treatment to libpe_rule as common.c seems to make curses calls. > > Could you considering updating your patch to include my proposed > additions below? And could you please include a description that describes > what the patch does? Perhaps something like this: > Sure, if you agree with the explanations above, I'll summarize them and add them in the patch which I'll resubmit to you for integration. > Explicitly link curses to libpengine > > When the ld option --as-needed is used the build fails, complaining > about missing curses symbols. This appears to be because without > the option curses was implicitly linked, somehow. But with the > option the implicit linking disapears, presumably because curses is > trimmed from the libraries linked to another library that is > subsequently linked to pengine, implicitly or otherwise. > > This patch resolves the problem by implicitly linking curses. > > It is of note that without this patch CURSESLIBS is not used anywhere. > > > >--- pengine/Makefile.am > > >+++ pengine/Makefile.am > > >@@ -58,6 +58,7 @@ > > > > > > # -L$(top_builddir)/lib/pils -lpils -export-dynamic -module > > > -avoid-version libpengine_la_SOURCES = pengine.c allocate.c utils.c > > > constraints.c \ > > > > > > native.c group.c clone.c master.c graph.c > > > > > >+libpengine_la_LIBADD = $(top_builddir)/lib/pengine/libpe_status.la > > +libpengine_la_LIBADD = $(top_builddir)/lib/pengine/libpe_status.la \ > + $(top_builddir)/lib/pengine/libpe_rules.la > > > > pengine_SOURCES = main.c > > > pengine_LDADD = $(COMMONLIBS) $(top_builddir)/lib/cib/libcib.la > > > > > >--- lib/pengine/Makefile.am > > >+++ lib/pengine/Makefile.am > > >@@ -34,7 +34,7 @@ > > libpe_rules_la_LDFLAGS = -version-info 2:0:0 > libpe_rules_la_SOURCES = $(rule_files) > +libpe_status_la_LIBADD = @CURSESLIBS@ > > > > libpe_status_la_LDFLAGS = -version-info 2:0:0 > > > libpe_status_la_SOURCES = $(rule_files) $(status_files) > > > > > >-libpe_status_la_LIBADD = -llrm > > >+libpe_status_la_LIBADD = -llrm @CURSESLIBS@ > > > > > > clean-generic: > > > rm -f *.log *.debug *~ > > > > Hi, > > > > This link explains the ld --as-needed flag better : > > http://www.gentoo.org/proj/en/qa/asneeded.xml > > > > As far as I know, Gentoo use the 'normal' ld GNU linker and those > > changes are required because some libs need symbols defined > > elsewhere. > > For more information and to show the details behind this, I'm > > attaching the failing build log I get if I don't patch before using > > the ld --as-needed flag. > > _______________________________________________ > Pacemaker mailing list: Pacemaker@oss.clusterlabs.org > http://oss.clusterlabs.org/mailman/listinfo/pacemaker > > Project Home: http://www.clusterlabs.org > Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf > Bugs: > http://developerbugs.linux-foundation.org/enter_bug.cgi?product=Pacemaker _______________________________________________ Pacemaker mailing list: Pacemaker@oss.clusterlabs.org http://oss.clusterlabs.org/mailman/listinfo/pacemaker Project Home: http://www.clusterlabs.org Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf Bugs: http://developerbugs.linux-foundation.org/enter_bug.cgi?product=Pacemaker
