Date: Mon, 22 Aug 2016 10:00:11 +0200 From: Dimitry Andric <dim@FreeBSD.org> To: Matthias Andree <matthias.andree@gmx.de> Cc: freebsd-ports@freebsd.org Subject: Re: Problems with out libgcc_s.so in base Message-ID: <0CA458FB-AF10-4765-9BE1-886A710BAA30@FreeBSD.org> In-Reply-To: <6f6a2c65-216a-3d7e-825f-222a06428f60@gmx.de> 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> <6f6a2c65-216a-3d7e-825f-222a06428f60@gmx.de>
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On 22 Aug 2016, at 08:26, Matthias Andree <matthias.andree@gmx.de> wrote: > > Am 18.08.2016 um 14:48 schrieb Dimitry Andric: >> 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 > > This in itself - to me - seems to be the actual problem, how do > different versions of the library the same major version? The gcc folks use symbol versioning, see: https://gcc.gnu.org/onlinedocs/libstdc++/manual/abi.html This works incrementally, so libgcc from gcc N is backwards compatible with all previous libgcc's from gcc < N. Not the other way around, of course. On Linux systems, there are no compatibility problems as we have seen them, because you simply install the most recent libgcc into /lib, and all applications will use that. Older applications will find their older ABI through symbol versioning. However, even on a Linux system you could get into trouble if you would compile and install a newer version of gcc than the system's default. Applications linked with that newer version would possibly require a newer libgcc ABI, and you would have the same problem that we have now. -Dimitry
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