Re: RFC: ld: Add --section-ordering-file FILE

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Tue, Apr 16, 2019 at 12:56 AM Nick Clifton <nickc@redhat.com> wrote:
>
> Hi H.J.
>
> > Does this sound a good idea?
>
> Maybe, but it does raise some questions in my mind:
>
>   * Why is this feature needed ?
>   * Couldn't the same result be achieved by using a custom linker script ?

Yes.  This is much easier to use than a custom linker script.

>   * How would the feature interact with linker scripts that already have
>     specific section placements (well ones that intersect with the sections
>     in the --section-order list) ?

--section-ordering-file is a short hand to place a list of sections at

 .text           :
  {
    *(.text.unlikely .text.*_unlikely .text.unlikely.*)
    *(.text.exit .text.exit.*)
    *(.text.startup .text.startup.*)
    INCLUDE config.section_ordering_file;  <<<<<<<<< here.
    *(.text.hot .text.hot.*)
    *(.text .stub .text.* .gnu.linkonce.t.*)
    /* .gnu.warning sections are handled specially by elf32.em.  */
    *(.gnu.warning)
  }

The contents of config.section_ordering_file won't change section
order before it.

>   * How would these sections be placed relative to other non-ordered sections ?

See above.

>   * How would --section-ordering-file interact with --sort-section ?

See above.

>   * Is it an error is a section in the ordering file is not present in the input ?
>

It is the same as an error in INCLUDE file.

-- 
H.J.