[PATCH v3] elf: Discard input .note.gnu.build-id sections

[H.J. Lu]

On Wed, Dec 1, 2021 at 3:58 AM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> On Wed, Dec 1, 2021 at 3:55 AM Alan Modra <amodra@gmail.com> wrote:
> >
> > On Tue, Nov 30, 2021 at 11:56:10PM -0800, Fangrui Song wrote:
> > > On 2021-12-01, Alan Modra via Binutils wrote:
> > > > On Tue, Nov 30, 2021 at 08:46:04PM -0800, H.J. Lu via Binutils wrote:
> > > > > 1. Discard input .note.gnu.build-id , excluding the first one.
> > > > > 2. Clear the build ID field before writing.
> > > > > 3. Use the input .note.gnu.build-id section if available.
> > > >
> > > > It's simpler to mark all input .note.gnu.build-id sections with
> > > > SEC_EXCLUDE then use bfd_make_section_anyway_with_flags to create a
> > > > new section.  That way you'll avoid any problems that might occur when
> > > > trying to use an existing section.  For example, the size might change
> > > > with a change in build-id style, leading to section contents buffer
> > > > overflow.
> > >
> > > For --build-id=none final link, should .note.gnu.build-id input sections
> > > be combined? This is the currently ld.bfd (and ld.lld)'s behavior.
> >
> > That's an interesting question.  We often supply an option such as
> > --build-id=none in order to turn off a project-wide default for
> > particular files.  So --build-id=none ought to behave the same as not
> > supplying any --build-id option.  What I'm saying is that the option
> > --build-id=none shouldn't necessarily mean "no build id", but we could
> > go that way if we also dropped .note.gnu.build-id sections when no
> > --build-id option was given.  I'm in favour of doing that.
> >
>
> Here is the v2 patch:
>
> 1. Use bfd_make_section_anyway_with_flags to create the output
> .note.gnu.build-id section.
> 2. Discard input .note.gnu.build-id sections.
>
> OK for master?
>

Here is the v3 patch:

1.  Use bfd_get_next_section_by_name to find input
.note.gnu.build-id sections.

OK for master?

-- 
H.J.
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