Re: [PATCH 2/2] x86/boot/compressed: Remove unnecessary sections from bzImage

[Fangrui Song]

On 2020-02-24, Arvind Sankar wrote:
> On Mon, Feb 24, 2020 at 01:28:28PM -0800, Fangrui Song wrote:
> > Hi Michael, please see my other reply on this thread: https://lkml.org/lkml/2020/2/24/47
> >
> > Synthesized sections can be matched as well. For example, SECTIONS { .pltfoo : { *(.plt) }} can rename the output section .plt to .pltfoo
> > It seems that in GNU ld, the synthesized section is associated with the
> > original object file, so it can be written as:
> >
> >    SECTIONS { .pltfoo : { a.o(.plt) }}
> >
> > In lld, you need a wildcard to match the synthesized section *(.plt)
> >
> > .rela.dyn is another example.
>
> With the BFD toolchain, file matching doesn't actually seem to work at
> least for .rela.dyn. I've tried playing around with it in the past and
> if you try to use file-matching to capture relocations from a particular
> input file, it just doesn't work sensibly.

I think most things are working in GNU ld...

/* a.x */
SECTIONS {
  .rela.pltfoo : { a.o(.rela.plt) }  /* *(.rela.plt) with lld */
  .rela.dynfoo : { a.o(.rela.data) } /* *(.rela.dyn) with lld */
}

% cat <<e > a.s
 .globl foo
 foo:
   call bar
 .data
 .quad quz
e
% as a.s -o a.o
% ld.bfd -T a.x a.o -shared -o a.so