Linker problems with system vs bundled libraries (RPATH vs RUNPATH) / LTO / gold

Дилян Палаузов dpa-libreoffice at
Fri Feb 1 21:12:43 UTC 2019


my initial understanding of the case “Linker problems with system vs bundled libraries (RPATH vs RUNPATH) ” is, that
ld.bfd and behave differently, which is exposed by invoking --enable-linker=

How do ld.bfd and differ, that triggered the problem?

Based on what does ./configure --help print behind --enable-lto: best used with “gold”.  Are there any known problems
with ld.bfd?

The "gold as linker" in comes from commit fc41132306 back in 2011 and ld.bfd can handle linker
plugins at least since 2015.

The AS_HELP_STRING for --enable-lto says "both gold and lld linkers generally use less memory and link faster". 
Compared to what?  It shoud say "compared to ld.bfd".

--enable-lto switches AR, NM and RANLIB to be gcc-ar, gcc-nm and gcc-ranlib, but… on some systems the binary is called
gcc-ar-4, for clang you have to use llvm-ar, which on some systems is called llvm-ar-5.0.  I am not aware of a single
autoconf project that manages this right; new versions of CMake do.

I propose removing all the LTO extras from LibreOffice.  Competent users are supposed to install the linker plugin and in $libdir/bfd-plugins and insert -flto into CFLAGS and CXXFLAGS, respectively -flto=6
in LDFLAGS.  Incompetent users don’t have a problem without LTO, as they do not know LTO exists.


On Fri, 2019-02-01 at 21:32 +0100, Michael Stahl wrote:
> On 01.02.19 20:12, Luboš Luňák wrote:
> > On Monday 28 of January 2019, Michael Stahl wrote:
> > > hope this will help:
> > > 
> > >
> > > 
> > > the idea is we use different symbol version for everything so LO libs
> > > call into bundled library, system libs call into system library.
> > > 
> > > haven't tested it though, just make check runs fine here...
> > 
> >   Yes, that works. But before you do, could you please e.g. add URL of this
> > discussion to the commit message? "unintended hilarity" is a rather poor
> > problem description.
> ... unfortunately it's too late to add anything to the commit message as 
> the patch somehow reviewed and pushed itself.
> well, anybody who knows what a gloriously misguided idea the ELF global 
> namespace is can think of any number of problems that would be fixed by 
> the patch :)
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