Re: [PATCH v3 1/2] xen/build: put image header into a separate section

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Tue, Mar 08, 2022 at 02:57:23PM +0100, Jan Beulich wrote:
> On 08.03.2022 14:49, Roger Pau Monne wrote:
> > So it can be explicitly placed ahead of the rest of the .text content
> > in the linker script (and thus the resulting image). This is a
> > prerequisite for further work that will add a catch-all to the text
> > section (.text.*).
> > 
> > Note that placement of the sections inside of .text is also slightly
> > adjusted to be more similar to the position found in the default GNU
> > ld linker script.
> > 
> > The special handling of the object file containing the header data as
> > the first object file passed to the linker command line can also be
> > removed.
> > 
> > While there also remove the special handling of efi/ on x86. There's
> > no need for the resulting object file to be passed in any special
> > order to the linker.
> > 
> > Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> 
> Looks good to me, but I have one question before feeling ready to
> offer R-b:
> 
> > @@ -86,8 +84,13 @@ SECTIONS
> >         *(.text.kexec)          /* Page aligned in the object file. */
> >         kexec_reloc_end = .;
> >  
> > -       *(.text.cold)
> > -       *(.text.unlikely)
> > +       *(.text.cold .text.cold.*)
> > +       *(.text.unlikely .text.*_unlikely .text.unlikely.*)
> 
> What generates .text.*_unlikely? And if anything really does, why
> would .text.cold not have a similar equivalent?

That matches what I saw in the default linker script from my version
of GNU ld:

    *(.text.unlikely .text.*_unlikely .text.unlikely.*)

I really don't know what could generate .text.*_unlikely, but since
it's part of the default linker script I assumed it was better to just
add it.

Thanks, Roger.