Date: Thu, 18 Aug 2016 16:50:49 -0700 From: Steve Kargl <sgk@troutmask.apl.washington.edu> To: Tijl Coosemans <tijl@FreeBSD.org> Cc: Dimitry Andric <dim@FreeBSD.org>, freebsd-toolchain@freebsd.org, freebsd-ports@freebsd.org, kargl@uw.edu Subject: Re: Problems with out libgcc_s.so in base Message-ID: <20160818235049.GA93186@troutmask.apl.washington.edu> In-Reply-To: <20160819011432.6f2eadbd@kalimero.tijl.coosemans.org> References: <20160814230351.GA10587@troutmask.apl.washington.edu> <20160814233430.GA35872@night.db.net> <20160817211710.GA59205@troutmask.apl.washington.edu> <20160818111521.7f79b9f8@kalimero.tijl.coosemans.org> <AB844E50-01A9-4559-8F7A-FE1F7B768F3A@FreeBSD.org> <20160819011432.6f2eadbd@kalimero.tijl.coosemans.org>
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On Fri, Aug 19, 2016 at 01:14:32AM +0200, Tijl Coosemans wrote: > > > > For example, on one of my systems, I now have these: > > > > /usr/local/lib/gcc47/libgcc_s.so.1 > > /usr/local/lib/gcc48/libgcc_s.so.1 > > /usr/local/lib/gcc49/libgcc_s.so.1 > > /usr/local/lib/gcc5/libgcc_s.so.1 > > /usr/local/lib/gcc6/libgcc_s.so.1 > > /usr/local/lib/gcc7/libgcc_s.so.1 > > > > So which one are you going to put at the front of the path? The gcc7 > > version? If you are lucky that one is backwards compatible with all the > > previous ones, but still I would like it much better if a program > > compiled by, say, gcc5 was linked *explicitly* against the gcc5 version > > of libgcc_s.so. > > > > Steve's proposed scheme solves that quite nicely, in my opinion. The > > problem is only in the details, as usual. There will be many configure > > scripts and libtool-like utilities out there, that assume libgcc must be > > linked using -lgcc_s, not -lgcc_s$VERSION. > > I now noticed there is a FAQ about this at > https://gcc.gnu.org/faq.html#rpath. It gives some suggestions including > creating wrapper scripts, but they wouldn't work when code is compiled > with gfortran but linked with Clang cc/c++. The only thing that works > in this case is -Wl,-rpath. Another option would be to create a port > that installs a recent version of libgcc in /usr/local/lib and let the > gcc ports use that instead of their own copy. elfdump -a libgfortran.so.3 shows dynamic: entry: 0 d_tag: DT_NEEDED d_val: libquadmath.so.0 entry: 1 d_tag: DT_NEEDED d_val: libm.so.5 entry: 2 d_tag: DT_NEEDED d_val: libgcc_s.so.1 entry: 3 d_tag: DT_NEEDED d_val: libc.so.7 entry: 4 d_tag: DT_SONAME d_val: libgfortran.so.3 entry: 5 d_tag: DT_RPATH d_val: /usr/local/lib/gcc6 I don't know how ELF or the ldd work, but shouldn't the DT_RPATH tell ldd to look for all of the above libraries in /usr/local/lib/gcc6 first. If a library isn't present, it would then look in ldconfig's hints file or fallback to /lib and /usr/lib/. But, I suppose we still run into issues as libgfortran.so.3 needs its companion libgcc_s.s.1 from DT_RPATH and libc.so.7 expects the one from /lib (or perhaps libcxxrt.so.1?). -- Steve
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