[Bug gold/15200] Runtime undefined reference to __exidx_start/_end

[petechou at gmail dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=15200

--- Comment #7 from pete <petechou at gmail dot com> 2013-03-07 06:43:08 UTC ---
I can think visibility does matter, but only for exporting the symbol or not.
In the previous case, gold does define the __bss symbols but not use the
definition in DSO, so I think we should still define section/segment symbols
locally.

-Pete

(In reply to comment #6)
> The symbols do not have same visibility.  gold in general is
> compatible with GNU ld.  If you look at src/ld/emulparams/, you will
> set that the __bss symbols are exported but the __exidx symbols are
> defined hidden.  gold matches the behaviour of ld.  If you look at
> defstd.cc in gold, you will again see that some of these symbols are
> hidden but some are not.
> 
> -Doug
> 
> 
> On Wed, Mar 6, 2013 at 9:31 PM, petechou at gmail dot com
> <address@hidden> wrote:
> > http://sourceware.org/bugzilla/show_bug.cgi?id=15200
> >
> > --- Comment #5 from pete <petechou at gmail dot com> 2013-03-07 05:31:25 
> > UTC ---
> > (In reply to comment #4)
> >> The symbols __exidx_end & __exidx_start were exported incorrectly in
> >> the past.  This is fixed in both ld & gold in the sense that these
> >> symbols are defined by not exported.  I think defining these symbols
> >> when there is a non-weak definition in a DSO is not the right thing to
> >> do.  This is basically multiple definition and usually is an error.
> >
> > If so, all section/segment symbols should be defined (if needed) by not
> > exported?
> >
> > But when there is a non-weak definition in a DSO, it's still possible to 
> > find
> > ld.gold define and export segment symbols like __bss_start (See
> > gold.defstd.cc:214. only_if_ref is set to false). And there is no multiple
> > definition error.
> >
> > $ readelf -Ds libc.so | grep __bss_start
> >   268 311: 0000d898     0 NOTYPE  GLOBAL DEFAULT ABS __bss_start__
> >   619 470: 0000d898     0 NOTYPE  GLOBAL DEFAULT ABS __bss_start
> >
> > $ arm-linux-androideabi-ld.gold -shared -o libplasma.so plasma.o libc.so
> >
> > $ readelf -s libplasma.so | grep __bss_start
> >     73: 00004148     0 NOTYPE  GLOBAL DEFAULT  ABS __bss_start
> >    168: 00004148     0 NOTYPE  GLOBAL DEFAULT  ABS __bss_start
> >
> >> I am not working on the Android NDK so I can't give you a good
> >> suggestion here.  Does using the latest NDK fixes your problem?
> >>
> >
> > Yes, there is no this issue with the latest NDK.
> >
> > -
> > Thanks,
> > Pete
> >
> > --
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