[Bug binutils/19446] BFD linker discards section without alloc section attribute under certain conditions

[xinliangli at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=19446

--- Comment #6 from David Li <xinliangli at gmail dot com> ---
(In reply to H.J. Lu from comment #5)
> (In reply to David Li from comment #4)
> > (In reply to H.J. Lu from comment #3)
> > > (In reply to David Li from comment #2)
> > > > (In reply to H.J. Lu from comment #1)
> > > > > Since UNREF section is not referenced, it should be GCed.  Am I 
> > > > > missing
> > > > > something?
> > > > 
> > > > Note that the section does not have 'a' bit -- just like debug sections.
> > > > Linker won't GC debug sections, right?
> > > 
> > > ld only treats known debug sections as debug sections.  Are you looking
> > > for a way to prevent unreferenced section from GC?
> > 
> > yes.
> > 
> 
> Will
> 
>         .globl  unref
>         .section        UNREF,"",@note
>         .align 8
>         .type   unref, @object
>         .size   unref, 8
> unref:
>         .quad   g0
> 
> work for you?
> 
> > > 
> > > > Also there is inconsistent behavior here -- when g0 is not referenced by
> > > > UNREF, UNREF will be kept by the linker.
> > > 
> > > g0 is removed by ld in binutils 2.26.
> > 
> > No -- that is not the point. The point is that if UNDEF section is defined
> > as follows,  ld *will* keep UNREF (I have not tried 2.26). What makes ld
> > think UNREF should be kept here as they are not known debug sections?
> > 
> > 
> > 
> >         .globl  unref
> >         .section        UNREF,"",@progbits
> >         .align 8
> >         .type   unref, @object
> >         .size   unref, 8
> > unref:
> >         .long 0
> > 
> >         .text
> >         .globl  main
> >         .type   main, @function
> 
> GCC in ld in binutils 2.26 will remove it.

making it a note section works fine for both ld and gold

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