Re: Varying filesize of libstdc++.so.6.0.19

[Jonathan Wakely <jwakely at redhat dot com>]

On 24/05/18 21:58 +0100, Mohan Ganesalingam wrote:
> Thanks very much for the quick reply!
>
> We think we have figured out some things about portability (of a library
> that links with libstdc++  *and no other libraries*) by testing – could I
> ask and see if they are reliably true?
>
> 1. If the library dynamically links with, say, libstdc++.so.6.0.19, then it
> can be compiled on one distro/version and used on another so long as
> libstdc++.so.6.0.19 or newer (and the requisite glibc) is present.
>
> 2. A compiled libstdc++.so.6.0.19 from one distro/version can be used on
> another distro/version. This means that if the library is statically linked
> against libstdc++ 6.0.19 on one distro/version, it will again work on
> other distro/versions
> as long as the right glibc is present.
>
> These seem to hold across (some version of) CentOS, Ubuntu, Fedora.
>
> NB. The library doesn't do anything that would explicitly make it OS
> -dependent – so it doesn't try to open system files, call 'system', access
> specific devices, etc..
>
> Is there a table somewhere that lists what minimum version of libc is
> required for each version of libstdc++?  (Similar to the tables in
> https://gcc.gnu.org/onlinedocs/libstdc++/manual/abi.html )

There is no minimum libc required for each version of libstdc++.
Anything newer than glibc 2.3 can be used, but an older glibc might
result in some features in libstdc++ being disabled.

The dependencies on glibc come from the glibc version that libstdc++
was built against. In other words the dependency depends how libstdc++
was built, not on the version of libstdc++ you use. That can vary
between OS distros, because two distros might use the same GCC release
but built against different glibc releases. That would mean their
libstdc++.so libraries have different dependencies on glibc.